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;;; eieio.el --- Enhanced Implementation of Emacs Interpreted Objects
;;;              or maybe Eric's Implementation of Emacs Intrepreted Objects

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;; Copyright (C) 1995-1996, 1998-2011  Free Software Foundation, Inc.
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;; Author: Eric M. Ludlam <zappo@gnu.org>
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;; Version: 1.3
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;; Keywords: OO, lisp

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; EIEIO is a series of Lisp routines which implements a subset of
;; CLOS, the Common Lisp Object System.  In addition, EIEIO also adds
;; a few new features which help it integrate more strongly with the
;; Emacs running environment.
;;
;; See eieio.texi for complete documentation on using this package.
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;;
;; Note: the implementation of the c3 algorithm is based on:
;;   Kim Barrett et al.: A Monotonic Superclass Linearization for Dylan
;;   Retrieved from:
;;   http://192.220.96.201/dylan/linearization-oopsla96.html
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;; There is funny stuff going on with typep and deftype.  This
;; is the only way I seem to be able to make this stuff load properly.

;; @TODO - fix :initform to be a form, not a quoted value
;; @TODO - Prefix non-clos functions with `eieio-'.

;;; Code:

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(eval-when-compile
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  (require 'cl))
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(defvar eieio-version "1.3"
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  "Current version of EIEIO.")

(defun eieio-version ()
  "Display the current version of EIEIO."
  (interactive)
  (message eieio-version))

(eval-and-compile
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;; About the above.  EIEIO must process its own code when it compiles
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;; itself, thus, by eval-and-compiling outselves, we solve the problem.

;; Compatibility
(if (fboundp 'compiled-function-arglist)

    ;; XEmacs can only access a compiled functions arglist like this:
    (defalias 'eieio-compiled-function-arglist 'compiled-function-arglist)

  ;; Emacs doesn't have this function, but since FUNC is a vector, we can just
  ;; grab the appropriate element.
  (defun eieio-compiled-function-arglist (func)
    "Return the argument list for the compiled function FUNC."
    (aref func 0))

  )


;;;
;; Variable declarations.
;;

(defvar eieio-hook nil
  "*This hook is executed, then cleared each time `defclass' is called.")

(defvar eieio-error-unsupported-class-tags nil
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  "Non-nil to throw an error if an encountered tag is unsupported.
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This may prevent classes from CLOS applications from being used with EIEIO
since EIEIO does not support all CLOS tags.")

(defvar eieio-skip-typecheck nil
  "*If non-nil, skip all slot typechecking.
Set this to t permanently if a program is functioning well to get a
small speed increase.  This variable is also used internally to handle
default setting for optimization purposes.")

(defvar eieio-optimize-primary-methods-flag t
  "Non-nil means to optimize the method dispatch on primary methods.")

;; State Variables
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;; FIXME: These two constants below should have an `eieio-' prefix added!!
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(defvar this nil
  "Inside a method, this variable is the object in question.
DO NOT SET THIS YOURSELF unless you are trying to simulate friendly slots.

Note: Embedded methods are no longer supported.  The variable THIS is
still set for CLOS methods for the sake of routines like
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`call-next-method'.")
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(defvar scoped-class nil
  "This is set to a class when a method is running.
This is so we know we are allowed to check private parts or how to
execute a `call-next-method'.  DO NOT SET THIS YOURSELF!")

(defvar eieio-initializing-object  nil
  "Set to non-nil while initializing an object.")

(defconst eieio-unbound
  (if (and (boundp 'eieio-unbound) (symbolp eieio-unbound))
      eieio-unbound
    (make-symbol "unbound"))
  "Uninterned symbol representing an unbound slot in an object.")

;; This is a bootstrap for eieio-default-superclass so it has a value
;; while it is being built itself.
(defvar eieio-default-superclass nil)

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;; FIXME: The constants below should have an `eieio-' prefix added!!
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(defconst class-symbol 1 "Class's symbol (self-referencing.).")
(defconst class-parent 2 "Class parent slot.")
(defconst class-children 3 "Class children class slot.")
(defconst class-symbol-obarray 4 "Obarray permitting fast access to variable position indexes.")
;; @todo
;; the word "public" here is leftovers from the very first version.
;; Get rid of it!
(defconst class-public-a 5 "Class attribute index.")
(defconst class-public-d 6 "Class attribute defaults index.")
(defconst class-public-doc 7 "Class documentation strings for attributes.")
(defconst class-public-type 8 "Class type for a slot.")
(defconst class-public-custom 9 "Class custom type for a slot.")
(defconst class-public-custom-label 10 "Class custom group for a slot.")
(defconst class-public-custom-group 11 "Class custom group for a slot.")
(defconst class-public-printer 12 "Printer for a slot.")
(defconst class-protection 13 "Class protection for a slot.")
(defconst class-initarg-tuples 14 "Class initarg tuples list.")
(defconst class-class-allocation-a 15 "Class allocated attributes.")
(defconst class-class-allocation-doc 16 "Class allocated documentation.")
(defconst class-class-allocation-type 17 "Class allocated value type.")
(defconst class-class-allocation-custom 18 "Class allocated custom descriptor.")
(defconst class-class-allocation-custom-label 19 "Class allocated custom descriptor.")
(defconst class-class-allocation-custom-group 20 "Class allocated custom group.")
(defconst class-class-allocation-printer 21 "Class allocated printer for a slot.")
(defconst class-class-allocation-protection 22 "Class allocated protection list.")
(defconst class-class-allocation-values 23 "Class allocated value vector.")
(defconst class-default-object-cache 24
  "Cache index of what a newly created object would look like.
This will speed up instantiation time as only a `copy-sequence' will
be needed, instead of looping over all the values and setting them
from the default.")
(defconst class-options 25
  "Storage location of tagged class options.
Stored outright without modifications or stripping.")

(defconst class-num-slots 26
  "Number of slots in the class definition object.")

(defconst object-class 1 "Index in an object vector where the class is stored.")
(defconst object-name 2 "Index in an object where the name is stored.")

(defconst method-static 0 "Index into :static tag on a method.")
(defconst method-before 1 "Index into :before tag on a method.")
(defconst method-primary 2 "Index into :primary tag on a method.")
(defconst method-after 3 "Index into :after tag on a method.")
(defconst method-num-lists 4 "Number of indexes into methods vector in which groups of functions are kept.")
(defconst method-generic-before 4 "Index into generic :before tag on a method.")
(defconst method-generic-primary 5 "Index into generic :primary tag on a method.")
(defconst method-generic-after 6 "Index into generic :after tag on a method.")
(defconst method-num-slots 7 "Number of indexes into a method's vector.")

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(defsubst eieio-specialized-key-to-generic-key (key)
  "Convert a specialized KEY into a generic method key."
  (cond ((eq key method-static) 0) ;; don't convert
	((< key method-num-lists) (+ key 3)) ;; The conversion
	(t key) ;; already generic.. maybe.
	))

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;;; Important macros used in eieio.
;;
(defmacro class-v (class)
  "Internal: Return the class vector from the CLASS symbol."
  ;; No check: If eieio gets this far, it's probably been checked already.
  `(get ,class 'eieio-class-definition))

(defmacro class-p (class)
  "Return t if CLASS is a valid class vector.
CLASS is a symbol."
  ;; this new method is faster since it doesn't waste time checking lots of
  ;; things.
  `(condition-case nil
       (eq (aref (class-v ,class) 0) 'defclass)
     (error nil)))

(defmacro eieio-object-p (obj)
  "Return non-nil if OBJ is an EIEIO object."
  `(condition-case nil
       (let ((tobj ,obj))
	 (and (eq (aref tobj 0) 'object)
	      (class-p (aref tobj object-class))))
     (error nil)))
(defalias 'object-p 'eieio-object-p)

(defmacro class-constructor (class)
  "Return the symbol representing the constructor of CLASS."
  `(aref (class-v ,class) class-symbol))

(defmacro generic-p (method)
  "Return t if symbol METHOD is a generic function.
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Only methods have the symbol `eieio-method-obarray' as a property
\(which contains a list of all bindings to that method type.)"
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  `(and (fboundp ,method) (get ,method 'eieio-method-obarray)))

(defun generic-primary-only-p (method)
  "Return t if symbol METHOD is a generic function with only primary methods.
Only methods have the symbol `eieio-method-obarray' as a property (which
contains a list of all bindings to that method type.)
Methods with only primary implementations are executed in an optimized way."
  (and (generic-p method)
       (let ((M (get method 'eieio-method-tree)))
	 (and (< 0 (length (aref M method-primary)))
	      (not (aref M method-static))
	      (not (aref M method-before))
	      (not (aref M method-after))
	      (not (aref M method-generic-before))
	      (not (aref M method-generic-primary))
	      (not (aref M method-generic-after))))
       ))

(defun generic-primary-only-one-p (method)
  "Return t if symbol METHOD is a generic function with only primary methods.
Only methods have the symbol `eieio-method-obarray' as a property (which
contains a list of all bindings to that method type.)
Methods with only primary implementations are executed in an optimized way."
  (and (generic-p method)
       (let ((M (get method 'eieio-method-tree)))
	 (and (= 1 (length (aref M method-primary)))
	      (not (aref M method-static))
	      (not (aref M method-before))
	      (not (aref M method-after))
	      (not (aref M method-generic-before))
	      (not (aref M method-generic-primary))
	      (not (aref M method-generic-after))))
       ))

(defmacro class-option-assoc (list option)
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  "Return from LIST the found OPTION, or nil if it doesn't exist."
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  `(car-safe (cdr (memq ,option ,list))))

(defmacro class-option (class option)
  "Return the value stored for CLASS' OPTION.
Return nil if that option doesn't exist."
  `(class-option-assoc (aref (class-v ,class) class-options) ',option))

(defmacro class-abstract-p (class)
  "Return non-nil if CLASS is abstract.
Abstract classes cannot be instantiated."
  `(class-option ,class :abstract))

(defmacro class-method-invocation-order (class)
  "Return the invocation order of CLASS.
Abstract classes cannot be instantiated."
  `(or (class-option ,class :method-invocation-order)
       :breadth-first))


;;; Defining a new class
;;
(defmacro defclass (name superclass slots &rest options-and-doc)
  "Define NAME as a new class derived from SUPERCLASS with SLOTS.
OPTIONS-AND-DOC is used as the class' options and base documentation.
SUPERCLASS is a list of superclasses to inherit from, with SLOTS
being the slots residing in that class definition.  NOTE: Currently
only one slot may exist in SUPERCLASS as multiple inheritance is not
yet supported.  Supported tags are:

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  :initform   - Initializing form.
  :initarg    - Tag used during initialization.
  :accessor   - Tag used to create a function to access this slot.
  :allocation - Specify where the value is stored.
                Defaults to `:instance', but could also be `:class'.
  :writer     - A function symbol which will `write' an object's slot.
  :reader     - A function symbol which will `read' an object.
  :type       - The type of data allowed in this slot (see `typep').
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  :documentation
              - A string documenting use of this slot.

The following are extensions on CLOS:
  :protection - Specify protection for this slot.
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                Defaults to `:public'.  Also use `:protected', or `:private'.
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  :custom     - When customizing an object, the custom :type.  Public only.
  :label      - A text string label used for a slot when customizing.
  :group      - Name of a customization group this slot belongs in.
  :printer    - A function to call to print the value of a slot.
                See `eieio-override-prin1' as an example.

A class can also have optional options.  These options happen in place
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of documentation (including a :documentation tag), in addition to
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documentation, or not at all.  Supported options are:

  :documentation - The doc-string used for this class.

Options added to EIEIO:

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  :allow-nil-initform - Non-nil to skip typechecking of null initforms.
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  :custom-groups      - List of custom group names.  Organizes slots into
                        reasonable groups for customizations.
  :abstract           - Non-nil to prevent instances of this class.
                        If a string, use as an error string if someone does
                        try to make an instance.
  :method-invocation-order
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                      - Control the method invocation order if there is
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                        multiple inheritance.  Valid values are:
                         :breadth-first - The default.
                         :depth-first

Options in CLOS not supported in EIEIO:

  :metaclass - Class to use in place of `standard-class'
  :default-initargs - Initargs to use when initializing new objects of
                      this class.

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Due to the way class options are set up, you can add any tags you wish,
and reference them using the function `class-option'."
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  ;; We must `eval-and-compile' this so that when we byte compile
  ;; an eieio program, there is no need to load it ahead of time.
  ;; It also provides lots of nice debugging errors at compile time.
  `(eval-and-compile
     (eieio-defclass ',name ',superclass ',slots ',options-and-doc)))

(defvar eieio-defclass-autoload-map (make-vector 7 nil)
  "Symbol map of superclasses we find in autoloads.")

;; We autoload this because it's used in `make-autoload'.
;;;###autoload
(defun eieio-defclass-autoload (cname superclasses filename doc)
  "Create autoload symbols for the EIEIO class CNAME.
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SUPERCLASSES are the superclasses that CNAME inherits from.
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DOC is the docstring for CNAME.
This function creates a mock-class for CNAME and adds it into
SUPERCLASSES as children.
It creates an autoload function for CNAME's constructor."
  ;; Assume we've already debugged inputs.

  (let* ((oldc (when (class-p cname) (class-v cname)))
	 (newc (make-vector class-num-slots nil))
	 )
    (if oldc
	nil ;; Do nothing if we already have this class.

      ;; Create the class in NEWC, but don't fill anything else in.
      (aset newc 0 'defclass)
      (aset newc class-symbol cname)

      (let ((clear-parent nil))
	;; No parents?
	(when (not superclasses)
	  (setq superclasses '(eieio-default-superclass)
		clear-parent t)
	  )

	;; Hook our new class into the existing structures so we can
	;; autoload it later.
	(dolist (SC superclasses)


	  ;; TODO - If we create an autoload that is in the map, that
	  ;;        map needs to be cleared!


	  ;; Does our parent exist?
	  (if (not (class-p SC))

	      ;; Create a symbol for this parent, and then store this
	      ;; parent on that symbol.
	      (let ((sym (intern (symbol-name SC) eieio-defclass-autoload-map)))
		(if (not (boundp sym))
		    (set sym (list cname))
		  (add-to-list sym cname))
		)

	    ;; We have a parent, save the child in there.
	    (when (not (member cname (aref (class-v SC) class-children)))
	      (aset (class-v SC) class-children
		    (cons cname (aref (class-v SC) class-children)))))

	  ;; save parent in child
	  (aset newc class-parent (cons SC (aref newc class-parent)))
	  )

	;; turn this into a useable self-pointing symbol
	(set cname cname)

	;; Store the new class vector definition into the symbol.  We need to
	;; do this first so that we can call defmethod for the accessor.
	;; The vector will be updated by the following while loop and will not
	;; need to be stored a second time.
	(put cname 'eieio-class-definition newc)

	;; Clear the parent
	(if clear-parent (aset newc class-parent nil))

	;; Create an autoload on top of our constructor function.
	(autoload cname filename doc nil nil)
	(autoload (intern (concat (symbol-name cname) "-p")) filename "" nil nil)
	(autoload (intern (concat (symbol-name cname) "-child-p")) filename "" nil nil)

	))))

(defsubst eieio-class-un-autoload (cname)
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  "If class CNAME is in an autoload state, load its file."
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  (when (eq (car-safe (symbol-function cname)) 'autoload)
    (load-library (car (cdr (symbol-function cname))))))

(defun eieio-defclass (cname superclasses slots options-and-doc)
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  "Define CNAME as a new subclass of SUPERCLASSES.
SLOTS are the slots residing in that class definition, and options or
documentation OPTIONS-AND-DOC is the toplevel documentation for this class.
See `defclass' for more information."
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  ;; Run our eieio-hook each time, and clear it when we are done.
  ;; This way people can add hooks safely if they want to modify eieio
  ;; or add definitions when eieio is loaded or something like that.
  (run-hooks 'eieio-hook)
  (setq eieio-hook nil)

  (if (not (symbolp cname)) (signal 'wrong-type-argument '(symbolp cname)))
  (if (not (listp superclasses)) (signal 'wrong-type-argument '(listp superclasses)))

  (let* ((pname (if superclasses superclasses nil))
	 (newc (make-vector class-num-slots nil))
	 (oldc (when (class-p cname) (class-v cname)))
	 (groups nil) ;; list of groups id'd from slots
	 (options nil)
	 (clearparent nil))

    (aset newc 0 'defclass)
    (aset newc class-symbol cname)

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    ;; If this class already existed, and we are updating its structure,
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    ;; make sure we keep the old child list.  This can cause bugs, but
    ;; if no new slots are created, it also saves time, and prevents
    ;; method table breakage, particularly when the users is only
    ;; byte compiling an EIEIO file.
    (if oldc
	(aset newc class-children (aref oldc class-children))
      ;; If the old class did not exist, but did exist in the autoload map, then adopt those children.
      ;; This is like the above, but deals with autoloads nicely.
      (let ((sym (intern-soft (symbol-name cname) eieio-defclass-autoload-map)))
	(when sym
	  (condition-case nil
	      (aset newc class-children (symbol-value sym))
	    (error nil))
	  (unintern (symbol-name cname) eieio-defclass-autoload-map)
	  ))
      )

    (cond ((and (stringp (car options-and-doc))
		(/= 1 (% (length options-and-doc) 2)))
	   (error "Too many arguments to `defclass'"))
	  ((and (symbolp (car options-and-doc))
		(/= 0 (% (length options-and-doc) 2)))
	   (error "Too many arguments to `defclass'"))
	  )

    (setq options
	  (if (stringp (car options-and-doc))
	      (cons :documentation options-and-doc)
	    options-and-doc))

    (if pname
	(progn
	  (while pname
	    (if (and (car pname) (symbolp (car pname)))
		(if (not (class-p (car pname)))
		    ;; bad class
		    (error "Given parent class %s is not a class" (car pname))
		  ;; good parent class...
		  ;; save new child in parent
		  (when (not (member cname (aref (class-v (car pname)) class-children)))
		    (aset (class-v (car pname)) class-children
			  (cons cname (aref (class-v (car pname)) class-children))))
		  ;; Get custom groups, and store them into our local copy.
		  (mapc (lambda (g) (add-to-list 'groups g))
			(class-option (car pname) :custom-groups))
		  ;; save parent in child
		  (aset newc class-parent (cons (car pname) (aref newc class-parent))))
	      (error "Invalid parent class %s" pname))
	    (setq pname (cdr pname)))
	  ;; Reverse the list of our parents so that they are prioritized in
	  ;; the same order as specified in the code.
	  (aset newc class-parent (nreverse (aref newc class-parent))) )
      ;; If there is nothing to loop over, then inherit from the
      ;; default superclass.
      (unless (eq cname 'eieio-default-superclass)
	;; adopt the default parent here, but clear it later...
	(setq clearparent t)
	;; save new child in parent
	(if (not (member cname (aref (class-v 'eieio-default-superclass) class-children)))
	    (aset (class-v 'eieio-default-superclass) class-children
		  (cons cname (aref (class-v 'eieio-default-superclass) class-children))))
	;; save parent in child
	(aset newc class-parent (list eieio-default-superclass))))

    ;; turn this into a useable self-pointing symbol
    (set cname cname)

    ;; These two tests must be created right away so we can have self-
    ;; referencing classes.  ei, a class whose slot can contain only
    ;; pointers to itself.

    ;; Create the test function
    (let ((csym (intern (concat (symbol-name cname) "-p"))))
      (fset csym
	    (list 'lambda (list 'obj)
		  (format "Test OBJ to see if it an object of type %s" cname)
		  (list 'and '(eieio-object-p obj)
			(list 'same-class-p 'obj cname)))))

    ;; Make sure the method invocation order  is a valid value.
    (let ((io (class-option-assoc options :method-invocation-order)))
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      (when (and io (not (member io '(:depth-first :breadth-first :c3))))
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	(error "Method invocation order %s is not allowed" io)
	))

    ;; Create a handy child test too
    (let ((csym (intern (concat (symbol-name cname) "-child-p"))))
      (fset csym
	    `(lambda (obj)
	       ,(format
		  "Test OBJ to see if it an object is a child of type %s"
		  cname)
	       (and (eieio-object-p obj)
		    (object-of-class-p obj ,cname))))

      ;; When using typep, (typep OBJ 'myclass) returns t for objects which
      ;; are subclasses of myclass.  For our predicates, however, it is
      ;; important for EIEIO to be backwards compatible, where
      ;; myobject-p, and myobject-child-p are different.
      ;; "cl" uses this technique to specify symbols with specific typep
      ;; test, so we can let typep have the CLOS documented behavior
      ;; while keeping our above predicate clean.

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      ;; It would be cleaner to use `defsetf' here, but that requires cl
      ;; at runtime.
      (put cname 'cl-deftype-handler
	   (list 'lambda () `(list 'satisfies (quote ,csym)))))
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    ;; before adding new slots, lets add all the methods and classes
    ;; in from the parent class
    (eieio-copy-parents-into-subclass newc superclasses)

    ;; Store the new class vector definition into the symbol.  We need to
    ;; do this first so that we can call defmethod for the accessor.
    ;; The vector will be updated by the following while loop and will not
    ;; need to be stored a second time.
    (put cname 'eieio-class-definition newc)

    ;; Query each slot in the declaration list and mangle into the
    ;; class structure I have defined.
    (while slots
      (let* ((slot1  (car slots))
	     (name    (car slot1))
	     (slot   (cdr slot1))
	     (acces   (plist-get slot ':accessor))
	     (init    (or (plist-get slot ':initform)
			  (if (member ':initform slot) nil
			    eieio-unbound)))
	     (initarg (plist-get slot ':initarg))
	     (docstr  (plist-get slot ':documentation))
	     (prot    (plist-get slot ':protection))
	     (reader  (plist-get slot ':reader))
	     (writer  (plist-get slot ':writer))
	     (alloc   (plist-get slot ':allocation))
	     (type    (plist-get slot ':type))
	     (custom  (plist-get slot ':custom))
	     (label   (plist-get slot ':label))
	     (customg (plist-get slot ':group))
	     (printer (plist-get slot ':printer))

	     (skip-nil (class-option-assoc options :allow-nil-initform))
	     )

	(if eieio-error-unsupported-class-tags
	    (let ((tmp slot))
	      (while tmp
		(if (not (member (car tmp) '(:accessor
					     :initform
					     :initarg
					     :documentation
					     :protection
					     :reader
					     :writer
					     :allocation
					     :type
					     :custom
					     :label
					     :group
					     :printer
					     :allow-nil-initform
					     :custom-groups)))
		    (signal 'invalid-slot-type (list (car tmp))))
		(setq tmp (cdr (cdr tmp))))))

	;; Clean up the meaning of protection.
	(cond ((or (eq prot 'public) (eq prot :public)) (setq prot nil))
	      ((or (eq prot 'protected) (eq prot :protected)) (setq prot 'protected))
	      ((or (eq prot 'private) (eq prot :private)) (setq prot 'private))
	      ((eq prot nil) nil)
	      (t (signal 'invalid-slot-type (list ':protection prot))))

	;; Make sure the :allocation parameter has a valid value.
	(if (not (or (not alloc) (eq alloc :class) (eq alloc :instance)))
	    (signal 'invalid-slot-type (list ':allocation alloc)))

	;; The default type specifier is supposed to be t, meaning anything.
	(if (not type) (setq type t))

	;; Label is nil, or a string
	(if (not (or (null label) (stringp label)))
	    (signal 'invalid-slot-type (list ':label label)))

	;; Is there an initarg, but allocation of class?
	(if (and initarg (eq alloc :class))
	    (message "Class allocated slots do not need :initarg"))

	;; intern the symbol so we can use it blankly
	(if initarg (set initarg initarg))

	;; The customgroup should be a list of symbols
	(cond ((null customg)
	       (setq customg '(default)))
	      ((not (listp customg))
	       (setq customg (list customg))))
	;; The customgroup better be a symbol, or list of symbols.
	(mapc (lambda (cg)
		(if (not (symbolp cg))
		    (signal 'invalid-slot-type (list ':group cg))))
		customg)

	;; First up, add this slot into our new class.
	(eieio-add-new-slot newc name init docstr type custom label customg printer
			     prot initarg alloc 'defaultoverride skip-nil)

	;; We need to id the group, and store them in a group list attribute.
	(mapc (lambda (cg) (add-to-list 'groups cg)) customg)

	;; anyone can have an accessor function.  This creates a function
	;; of the specified name, and also performs a `defsetf' if applicable
	;; so that users can `setf' the space returned by this function
	(if acces
	    (progn
	      (eieio-defmethod acces
		(list (if (eq alloc :class) :static :primary)
		      (list (list 'this cname))
		      (format
		       "Retrieves the slot `%s' from an object of class `%s'"
		       name cname)
		      (list 'if (list 'slot-boundp 'this (list 'quote name))
			    (list 'eieio-oref 'this (list 'quote name))
			    ;; Else - Some error?  nil?
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			    nil)))

	      ;; Provide a setf method.  It would be cleaner to use
	      ;; defsetf, but that would require CL at runtime.
	      (put acces 'setf-method
		   `(lambda (widget)
		      (let* ((--widget-sym-- (make-symbol "--widget--"))
			     (--store-sym-- (make-symbol "--store--")))
			(list
			 (list --widget-sym--)
			 (list widget)
			 (list --store-sym--)
			 (list 'eieio-oset --widget-sym-- '',name --store-sym--)
			 (list 'getfoo --widget-sym--)))))))

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	;; If a writer is defined, then create a generic method of that
	;; name whose purpose is to set the value of the slot.
	(if writer
	    (progn
	      (eieio-defmethod writer
		(list (list (list 'this cname) 'value)
		      (format "Set the slot `%s' of an object of class `%s'"
			      name cname)
		      `(setf (slot-value this ',name) value)))
	      ))
	;; If a reader is defined, then create a generic method
	;; of that name whose purpose is to access this slot value.
	(if reader
	    (progn
	      (eieio-defmethod reader
		(list (list (list 'this cname))
		      (format "Access the slot `%s' from object of class `%s'"
			      name cname)
		      `(slot-value this ',name)))))
	)
      (setq slots (cdr slots)))

    ;; Now that everything has been loaded up, all our lists are backwards!  Fix that up now.
    (aset newc class-public-a (nreverse (aref newc class-public-a)))
    (aset newc class-public-d (nreverse (aref newc class-public-d)))
    (aset newc class-public-doc (nreverse (aref newc class-public-doc)))
    (aset newc class-public-type
	  (apply 'vector (nreverse (aref newc class-public-type))))
    (aset newc class-public-custom (nreverse (aref newc class-public-custom)))
    (aset newc class-public-custom-label (nreverse (aref newc class-public-custom-label)))
    (aset newc class-public-custom-group (nreverse (aref newc class-public-custom-group)))
    (aset newc class-public-printer (nreverse (aref newc class-public-printer)))
    (aset newc class-protection (nreverse (aref newc class-protection)))
    (aset newc class-initarg-tuples (nreverse (aref newc class-initarg-tuples)))

    ;; The storage for class-class-allocation-type needs to be turned into
    ;; a vector now.
    (aset newc class-class-allocation-type
	  (apply 'vector (aref newc class-class-allocation-type)))

    ;; Also, take class allocated values, and vectorize them for speed.
    (aset newc class-class-allocation-values
	  (apply 'vector (aref newc class-class-allocation-values)))

    ;; Attach slot symbols into an obarray, and store the index of
    ;; this slot as the variable slot in this new symbol.  We need to
    ;; know about primes, because obarrays are best set in vectors of
    ;; prime number length, and we also need to make our vector small
    ;; to save space, and also optimal for the number of items we have.
    (let* ((cnt 0)
	   (pubsyms (aref newc class-public-a))
	   (prots (aref newc class-protection))
	   (l (length pubsyms))
	   (vl (let ((primes '( 3 5 7 11 13 17 19 23 29 31 37 41 43 47
				  53 59 61 67 71 73 79 83 89 97 101 )))
		 (while (and primes (< (car primes) l))
		   (setq primes (cdr primes)))
		 (car primes)))
	   (oa (make-vector vl 0))
	   (newsym))
      (while pubsyms
	(setq newsym (intern (symbol-name (car pubsyms)) oa))
	(set newsym cnt)
	(setq cnt (1+ cnt))
	(if (car prots) (put newsym 'protection (car prots)))
	(setq pubsyms (cdr pubsyms)
	      prots (cdr prots)))
      (aset newc class-symbol-obarray oa)
      )

    ;; Create the constructor function
    (if (class-option-assoc options :abstract)
	;; Abstract classes cannot be instantiated.  Say so.
	(let ((abs (class-option-assoc options :abstract)))
	  (if (not (stringp abs))
	      (setq abs (format "Class %s is abstract" cname)))
	  (fset cname
		`(lambda (&rest stuff)
		   ,(format "You cannot create a new object of type %s" cname)
		   (error ,abs))))

      ;; Non-abstract classes need a constructor.
      (fset cname
	    `(lambda (newname &rest slots)
	       ,(format "Create a new object with name NAME of class type %s" cname)
	       (apply 'constructor ,cname newname slots)))
      )

    ;; Set up a specialized doc string.
    ;; Use stored value since it is calculated in a non-trivial way
    (put cname 'variable-documentation
	 (class-option-assoc options :documentation))

    ;; We have a list of custom groups.  Store them into the options.
    (let ((g (class-option-assoc options :custom-groups)))
      (mapc (lambda (cg) (add-to-list 'g cg)) groups)
      (if (memq :custom-groups options)
	  (setcar (cdr (memq :custom-groups options)) g)
	(setq options (cons :custom-groups (cons g options)))))

    ;; Set up the options we have collected.
    (aset newc class-options options)

    ;; if this is a superclass, clear out parent (which was set to the
    ;; default superclass eieio-default-superclass)
    (if clearparent (aset newc class-parent nil))

    ;; Create the cached default object.
    (let ((cache (make-vector (+ (length (aref newc class-public-a))
				 3) nil)))
      (aset cache 0 'object)
      (aset cache object-class cname)
      (aset cache object-name 'default-cache-object)
      (let ((eieio-skip-typecheck t))
	;; All type-checking has been done to our satisfaction
	;; before this call.  Don't waste our time in this call..
	(eieio-set-defaults cache t))
      (aset newc class-default-object-cache cache))

    ;; Return our new class object
    ;; newc
    cname
    ))

(defun eieio-perform-slot-validation-for-default (slot spec value skipnil)
  "For SLOT, signal if SPEC does not match VALUE.
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If SKIPNIL is non-nil, then if VALUE is nil return t instead."
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  (if (and (not (eieio-eval-default-p value))
	   (not eieio-skip-typecheck)
	   (not (and skipnil (null value)))
	   (not (eieio-perform-slot-validation spec value)))
      (signal 'invalid-slot-type (list slot spec value))))
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(defun eieio-add-new-slot (newc a d doc type cust label custg print prot init alloc
				 &optional defaultoverride skipnil)
  "Add into NEWC attribute A.
If A already exists in NEWC, then do nothing.  If it doesn't exist,
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then also add in D (default), DOC, TYPE, CUST, LABEL, CUSTG, PRINT, PROT, and INIT arg.
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Argument ALLOC specifies if the slot is allocated per instance, or per class.
If optional DEFAULTOVERRIDE is non-nil, then if A exists in NEWC,
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we must override its value for a default.
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Optional argument SKIPNIL indicates if type checking should be skipped
if default value is nil."
  ;; Make sure we duplicate those items that are sequences.
  (condition-case nil
      (if (sequencep d) (setq d (copy-sequence d)))
    ;; This copy can fail on a cons cell with a non-cons in the cdr.  Lets skip it if it doesn't work.
    (error nil))
  (if (sequencep type) (setq type (copy-sequence type)))
  (if (sequencep cust) (setq cust (copy-sequence cust)))
  (if (sequencep custg) (setq custg (copy-sequence custg)))

  ;; To prevent override information w/out specification of storage,
  ;; we need to do this little hack.
  (if (member a (aref newc class-class-allocation-a)) (setq alloc ':class))

  (if (or (not alloc) (and (symbolp alloc) (eq alloc ':instance)))
      ;; In this case, we modify the INSTANCE version of a given slot.

      (progn

	;; Only add this element if it is so-far unique
	(if (not (member a (aref newc class-public-a)))
	    (progn
	      (eieio-perform-slot-validation-for-default a type d skipnil)
	      (aset newc class-public-a (cons a (aref newc class-public-a)))
	      (aset newc class-public-d (cons d (aref newc class-public-d)))
	      (aset newc class-public-doc (cons doc (aref newc class-public-doc)))
	      (aset newc class-public-type (cons type (aref newc class-public-type)))
	      (aset newc class-public-custom (cons cust (aref newc class-public-custom)))
	      (aset newc class-public-custom-label (cons label (aref newc class-public-custom-label)))
	      (aset newc class-public-custom-group (cons custg (aref newc class-public-custom-group)))
	      (aset newc class-public-printer (cons print (aref newc class-public-printer)))
	      (aset newc class-protection (cons prot (aref newc class-protection)))
	      (aset newc class-initarg-tuples (cons (cons init a) (aref newc class-initarg-tuples)))
	      )
	  ;; When defaultoverride is true, we are usually adding new local
	  ;; attributes which must override the default value of any slot
	  ;; passed in by one of the parent classes.
	  (when defaultoverride
	    ;; There is a match, and we must override the old value.
	    (let* ((ca (aref newc class-public-a))
		   (np (member a ca))
		   (num (- (length ca) (length np)))
		   (dp (if np (nthcdr num (aref newc class-public-d))
			 nil))
		   (tp (if np (nth num (aref newc class-public-type))))
		   )
	      (if (not np)
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		  (error "EIEIO internal error overriding default value for %s"
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			 a)
		;; If type is passed in, is it the same?
		(if (not (eq type t))
		    (if (not (equal type tp))
			(error
			 "Child slot type `%s' does not match inherited type `%s' for `%s'"
			 type tp a)))
		;; If we have a repeat, only update the initarg...
		(unless (eq d eieio-unbound)
		  (eieio-perform-slot-validation-for-default a tp d skipnil)
		  (setcar dp d))
		;; If we have a new initarg, check for it.
		(when init
		  (let* ((inits (aref newc class-initarg-tuples))
			 (inita (rassq a inits)))
		    ;; Replace the CAR of the associate INITA.
		    ;;(message "Initarg: %S replace %s" inita init)
		    (setcar inita init)
		    ))

		;; PLN Tue Jun 26 11:57:06 2007 : The protection is
		;; checked and SHOULD match the superclass
		;; protection. Otherwise an error is thrown. However
		;; I wonder if a more flexible schedule might be
		;; implemented.
		;;
		;; EML - We used to have (if prot... here,
		;;       but a prot of 'nil means public.
		;;
		(let ((super-prot (nth num (aref newc class-protection)))
		      )
		  (if (not (eq prot super-prot))
		      (error "Child slot protection `%s' does not match inherited protection `%s' for `%s'"
			     prot super-prot a)))
		;; End original PLN

		;; PLN Tue Jun 26 11:57:06 2007 :
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		;; Do a non redundant combination of ancient custom
		;; groups and new ones.
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		(when custg
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		  (let* ((groups
			  (nthcdr num (aref newc class-public-custom-group)))
			 (list1 (car groups))
			 (list2 (if (listp custg) custg (list custg))))
		    (if (< (length list1) (length list2))
			(setq list1 (prog1 list2 (setq list2 list1))))
		    (dolist (elt list2)
		      (unless (memq elt list1)
			(push elt list1)))
		    (setcar groups list1)))
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		;;  End PLN

		;;  PLN Mon Jun 25 22:44:34 2007 : If a new cust is
		;;  set, simply replaces the old one.
		(when cust
		  ;; (message "Custom type redefined to %s" cust)
		  (setcar (nthcdr num (aref newc class-public-custom)) cust))

		;; If a new label is specified, it simply replaces
		;; the old one.
		(when label
		  ;; (message "Custom label redefined to %s" label)
		  (setcar (nthcdr num (aref newc class-public-custom-label)) label))
		;;  End PLN

		;; PLN Sat Jun 30 17:24:42 2007 : when a new
		;; doc is specified, simply replaces the old one.
		(when doc
		  ;;(message "Documentation redefined to %s" doc)
		  (setcar (nthcdr num (aref newc class-public-doc))
			  doc))
		;; End PLN

		;; If a new printer is specified, it simply replaces
		;; the old one.
		(when print
		  ;; (message "printer redefined to %s" print)
		  (setcar (nthcdr num (aref newc class-public-printer)) print))

		)))
	  ))

    ;; CLASS ALLOCATED SLOTS
    (let ((value (eieio-default-eval-maybe d)))
      (if (not (member a (aref newc class-class-allocation-a)))
	  (progn
	    (eieio-perform-slot-validation-for-default a type value skipnil)
	    ;; Here we have found a :class version of a slot.  This
	    ;; requires a very different aproach.
	    (aset newc class-class-allocation-a (cons a (aref newc class-class-allocation-a)))
	    (aset newc class-class-allocation-doc (cons doc (aref newc class-class-allocation-doc)))
	    (aset newc class-class-allocation-type (cons type (aref newc class-class-allocation-type)))
	    (aset newc class-class-allocation-custom (cons cust (aref newc class-class-allocation-custom)))
	    (aset newc class-class-allocation-custom-label (cons label (aref newc class-class-allocation-custom-label)))
	    (aset newc class-class-allocation-custom-group (cons custg (aref newc class-class-allocation-custom-group)))
	    (aset newc class-class-allocation-protection (cons prot (aref newc class-class-allocation-protection)))
	    ;; Default value is stored in the 'values section, since new objects
	    ;; can't initialize from this element.
	    (aset newc class-class-allocation-values (cons value (aref newc class-class-allocation-values))))
	(when defaultoverride
	  ;; There is a match, and we must override the old value.
	  (let* ((ca (aref newc class-class-allocation-a))
		 (np (member a ca))
		 (num (- (length ca) (length np)))
		 (dp (if np
			 (nthcdr num
				 (aref newc class-class-allocation-values))
		       nil))
		 (tp (if np (nth num (aref newc class-class-allocation-type))
		       nil)))
	    (if (not np)
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		(error "EIEIO internal error overriding default value for %s"
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		       a)
	      ;; If type is passed in, is it the same?
	      (if (not (eq type t))
		  (if (not (equal type tp))
		      (error
		       "Child slot type `%s' does not match inherited type `%s' for `%s'"
		       type tp a)))
	      ;; EML - Note: the only reason to override a class bound slot
	      ;;       is to change the default, so allow unbound in.

	      ;; If we have a repeat, only update the vlaue...
	      (eieio-perform-slot-validation-for-default a tp value skipnil)
	      (setcar dp value))

	    ;; PLN Tue Jun 26 11:57:06 2007 : The protection is
	    ;; checked and SHOULD match the superclass
	    ;; protection. Otherwise an error is thrown. However
	    ;; I wonder if a more flexible schedule might be
	    ;; implemented.
	    (let ((super-prot
		   (car (nthcdr num (aref newc class-class-allocation-protection)))))
	      (if (not (eq prot super-prot))
		  (error "Child slot protection `%s' does not match inherited protection `%s' for `%s'"
			 prot super-prot a)))
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	    ;; Do a non redundant combination of ancient custom groups
	    ;; and new ones.
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	    (when custg
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	      (let* ((groups
		      (nthcdr num (aref newc class-class-allocation-custom-group)))
		     (list1 (car groups))
		     (list2 (if (listp custg) custg (list custg))))
		(if (< (length list1) (length list2))
		    (setq list1 (prog1 list2 (setq list2 list1))))
		(dolist (elt list2)
		  (unless (memq elt list1)
		    (push elt list1)))
		(setcar groups list1)))
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	    ;; PLN Sat Jun 30 17:24:42 2007 : when a new
	    ;; doc is specified, simply replaces the old one.
	    (when doc
	      ;;(message "Documentation redefined to %s" doc)
	      (setcar (nthcdr num (aref newc class-class-allocation-doc))
		      doc))
	    ;; End PLN

	    ;; If a new printer is specified, it simply replaces
	    ;; the old one.
	    (when print
	      ;; (message "printer redefined to %s" print)
	      (setcar (nthcdr num (aref newc class-class-allocation-printer)) print))

	    ))
	))
    ))

(defun eieio-copy-parents-into-subclass (newc parents)
  "Copy into NEWC the slots of PARENTS.
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Follow the rules of not overwriting early parents when applying to
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the new child class."
  (let ((ps (aref newc class-parent))
	(sn (class-option-assoc (aref newc class-options)
				':allow-nil-initform)))
    (while ps
      ;; First, duplicate all the slots of the parent.
      (let ((pcv (class-v (car ps))))
	(let ((pa (aref pcv class-public-a))
	      (pd (aref pcv class-public-d))
	      (pdoc (aref pcv class-public-doc))
	      (ptype (aref pcv class-public-type))
	      (pcust (aref pcv class-public-custom))
	      (plabel (aref pcv class-public-custom-label))
	      (pcustg (aref pcv class-public-custom-group))
	      (printer (aref pcv class-public-printer))
	      (pprot (aref pcv class-protection))
	      (pinit (aref pcv class-initarg-tuples))
	      (i 0))
	  (while pa
	    (eieio-add-new-slot newc
				 (car pa) (car pd) (car pdoc) (aref ptype i)
				 (car pcust) (car plabel) (car pcustg)
				 (car printer)
				 (car pprot) (car-safe (car pinit)) nil nil sn)
	    ;; Increment each value.
	    (setq pa (cdr pa)
		  pd (cdr pd)
		  pdoc (cdr pdoc)
		  i (1+ i)
		  pcust (cdr pcust)
		  plabel (cdr plabel)
		  pcustg (cdr pcustg)
		  printer (cdr printer)
		  pprot (cdr pprot)
		  pinit (cdr pinit))
	    )) ;; while/let
	;; Now duplicate all the class alloc slots.
	(let ((pa (aref pcv class-class-allocation-a))
	      (pdoc (aref pcv class-class-allocation-doc))
	      (ptype (aref pcv class-class-allocation-type))
	      (pcust (aref pcv class-class-allocation-custom))
	      (plabel (aref pcv class-class-allocation-custom-label))
	      (pcustg (aref pcv class-class-allocation-custom-group))
	      (printer (aref pcv class-class-allocation-printer))
	      (pprot (aref pcv class-class-allocation-protection))
	      (pval (aref pcv class-class-allocation-values))
	      (i 0))
	  (while pa
	    (eieio-add-new-slot newc
				 (car pa) (aref pval i) (car pdoc) (aref ptype i)
				 (car pcust) (car plabel) (car pcustg)
				 (car printer)
				 (car pprot) nil ':class sn)
	    ;; Increment each value.
	    (setq pa (cdr pa)
		  pdoc (cdr pdoc)
		  pcust (cdr pcust)
		  plabel (cdr plabel)
		  pcustg (cdr pcustg)
		  printer (cdr printer)
		  pprot (cdr pprot)
		  i (1+ i))
	    ))) ;; while/let
      ;; Loop over each parent class
      (setq ps (cdr ps)))
    ))

;;; CLOS style implementation of object creators.
;;
(defun make-instance (class &rest initargs)
  "Make a new instance of CLASS based on INITARGS.
CLASS is a class symbol.  For example:

  (make-instance 'foo)

  INITARGS is a property list with keywords based on the :initarg
for each slot.  For example:

  (make-instance 'foo :slot1 value1 :slotN valueN)

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Compatibility note:
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If the first element of INITARGS is a string, it is used as the
name of the class.

In EIEIO, the class' constructor requires a name for use when printing.
`make-instance' in CLOS doesn't use names the way Emacs does, so the
class is used as the name slot instead when INITARGS doesn't start with
a string."
  (if (and (car initargs) (stringp (car initargs)))
      (apply (class-constructor class) initargs)
    (apply  (class-constructor class)
	    (cond ((symbolp class) (symbol-name class))
		  (t (format "%S" class)))
	    initargs)))


;;; CLOS methods and generics
;;
(defmacro defgeneric (method args &optional doc-string)
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  "Create a generic function METHOD.
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DOC-STRING is the base documentation for this class.  A generic
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function has no body, as its purpose is to decide which method body
is appropriate to use.  Uses `defmethod' to create methods, and calls
`defgeneric' for you.  With this implementation the ARGS are
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currently ignored.  You can use `defgeneric' to apply specialized
top level documentation to a method."
  `(eieio-defgeneric (quote ,method) ,doc-string))

(defun eieio-defgeneric-form (method doc-string)
  "The lambda form that would be used as the function defined on METHOD.
All methods should call the same EIEIO function for dispatch.
DOC-STRING is the documentation attached to METHOD."
  `(lambda (&rest local-args)
     ,doc-string
     (eieio-generic-call (quote ,method) local-args)))

(defsubst eieio-defgeneric-reset-generic-form (method)
  "Setup METHOD to call the generic form."
  (let ((doc-string (documentation method)))
    (fset method (eieio-defgeneric-form method doc-string))))

(defun eieio-defgeneric-form-primary-only (method doc-string)
  "The lambda form that would be used as the function defined on METHOD.
All methods should call the same EIEIO function for dispatch.
DOC-STRING is the documentation attached to METHOD."
  `(lambda (&rest local-args)
     ,doc-string
     (eieio-generic-call-primary-only (quote ,method) local-args)))

(defsubst eieio-defgeneric-reset-generic-form-primary-only (method)
  "Setup METHOD to call the generic form."
  (let ((doc-string (documentation method)))
    (fset method (eieio-defgeneric-form-primary-only method doc-string))))

(defun eieio-defgeneric-form-primary-only-one (method doc-string
						      class
						      impl
						      )
  "The lambda form that would be used as the function defined on METHOD.
All methods should call the same EIEIO function for dispatch.
DOC-STRING is the documentation attached to METHOD.
CLASS is the class symbol needed for private method access.
IMPL is the symbol holding the method implementation."
  ;; NOTE: I tried out byte compiling this little fcn.  Turns out it
  ;; is faster to execute this for not byte-compiled.  ie, install this,
  ;; then measure calls going through here.  I wonder why.
  (require 'bytecomp)
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  (let ((byte-compile-warnings nil))
    (byte-compile
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     `(lambda (&rest local-args)
	,doc-string
	;; This is a cool cheat.  Usually we need to look up in the
	;; method table to find out if there is a method or not.  We can
	;; instead make that determination at load time when there is
	;; only one method.  If the first arg is not a child of the class
	;; of that one implementation, then clearly, there is no method def.
	(if (not (eieio-object-p (car local-args)))
	    ;; Not an object.  Just signal.
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	    (signal 'no-method-definition
                    (list ,(list 'quote method) local-args))
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	  ;; We do have an object.  Make sure it is the right type.
	  (if ,(if (eq class eieio-default-superclass)
		   nil ; default superclass means just an obj.  Already asked.
		 `(not (child-of-class-p (aref (car local-args) object-class)
					 ,(list 'quote class)))
		 )

	      ;; If not the right kind of object, call no applicable
	      (apply 'no-applicable-method (car local-args)
		     ,(list 'quote method) local-args)

	    ;; It is ok, do the call.
	    ;; Fill in inter-call variables then evaluate the method.
	    (let ((scoped-class ,(list 'quote class))
		  (eieio-generic-call-next-method-list nil)
		  (eieio-generic-call-key method-primary)
		  (eieio-generic-call-methodname ,(list 'quote method))
		  (eieio-generic-call-arglst local-args)
		  )
	      (apply ,(list 'quote impl) local-args)
	      ;(,impl local-args)
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	      )))))))
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(defsubst eieio-defgeneric-reset-generic-form-primary-only-one (method)
  "Setup METHOD to call the generic form."
  (let* ((doc-string (documentation method))
	 (M (get method 'eieio-method-tree))
	 (entry (car (aref M method-primary)))
	 )
    (fset method (eieio-defgeneric-form-primary-only-one
		  method doc-string
		  (car entry)
		  (cdr entry)
		  ))))

(defun eieio-defgeneric (method doc-string)
  "Engine part to `defgeneric' macro defining METHOD with DOC-STRING."
  (if (and (fboundp method) (not (generic-p method))
	   (or (byte-code-function-p (symbol-function method))
	       (not (eq 'autoload (car (symbol-function method)))))
	   )
      (error "You cannot create a generic/method over an existing symbol: %s"
	     method))
  ;; Don't do this over and over.
  (unless (fboundp 'method)
    ;; This defun tells emacs where the first definition of this
    ;; method is defined.
    `(defun ,method nil)
    ;; Make sure the method tables are installed.
    (eieiomt-install method)
    ;; Apply the actual body of this function.
    (fset method (eieio-defgeneric-form method doc-string))
    ;; Return the method
    'method))

(defun eieio-unbind-method-implementations (method)
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  "Make the generic method METHOD have no implementations.
It will leave the original generic function in place,
but remove reference to all implementations of METHOD."
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  (put method 'eieio-method-tree nil)
  (put method 'eieio-method-obarray nil))

(defmacro defmethod (method &rest args)
  "Create a new METHOD through `defgeneric' with ARGS.

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The optional second argument KEY is a specifier that
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modifies how the method is called, including:
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   :before  - Method will be called before the :primary
   :primary - The default if not specified
   :after   - Method will be called after the :primary
   :static  - First arg could be an object or class
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The next argument is the ARGLIST.  The ARGLIST specifies the arguments
to the method as with `defun'.  The first argument can have a type
specifier, such as:
  ((VARNAME CLASS) ARG2 ...)
where VARNAME is the name of the local variable for the method being
created.  The CLASS is a class symbol for a class made with `defclass'.
A DOCSTRING comes after the ARGLIST, and is optional.
All the rest of the args are the BODY of the method.  A method will
return the value of the last form in the BODY.

Summary:

 (defmethod mymethod [:before | :primary | :after | :static]
                     ((typearg class-name) arg2 &optional opt &rest rest)
    \"doc-string\"
     body)"
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  (let* ((key (cond ((or (eq ':BEFORE (car args))
                         (eq ':before (car args)))
                     (setq args (cdr args))
                     :before)
                    ((or (eq ':AFTER (car args))
                         (eq ':after (car args)))
                     (setq args (cdr args))
                     :after)
                    ((or (eq ':PRIMARY (car args))
                         (eq ':primary (car args)))
                     (setq args (cdr args))
                     :primary)
                    ((or (eq ':STATIC (car args))
                         (eq ':static (car args)))
                     (setq args (cdr args))
                     :static)
                    (t nil)))
	 (params (car args))
	 (lamparams
          (mapcar (lambda (param) (if (listp param) (car param) param))
                  params))
	 (arg1 (car params))
	 (class (if (listp arg1) (nth 1 arg1) nil)))
    `(eieio-defmethod ',method
                      '(,@(if key (list key))
                        ,params)
                      (lambda ,lamparams ,@(cdr args)))))

(defun eieio-defmethod (method args &optional code)
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  "Work part of the `defmethod' macro defining METHOD with ARGS."
  (let ((key nil) (body nil) (firstarg nil) (argfix nil) (argclass nil) loopa)
    ;; find optional keys
    (setq key
	  (cond ((or (eq ':BEFORE (car args))
		     (eq ':before (car args)))
		 (setq args (cdr args))
		 method-before)
		((or (eq ':AFTER (car args))
		     (eq ':after (car args)))
		 (setq args (cdr args))
		 method-after)
		((or (eq ':PRIMARY (car args))
		     (eq ':primary (car args)))
		 (setq args (cdr args))
		 method-primary)
		((or (eq ':STATIC (car args))
		     (eq ':static (car args)))
		 (setq args (cdr args))
		 method-static)
		;; Primary key
		(t method-primary)))
    ;; get body, and fix contents of args to be the arguments of the fn.
    (setq body (cdr args)
	  args (car args))
    (setq loopa args)
    ;; Create a fixed version of the arguments
    (while loopa
      (setq argfix (cons (if (listp (car loopa)) (car (car loopa)) (car loopa))
			 argfix))
      (setq loopa (cdr loopa)))
    ;; make sure there is a generic
    (eieio-defgeneric
     method
     (if (stringp (car body))
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	 (car body) (format "Generically created method `%s'." method)))
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    ;; create symbol for property to bind to.  If the first arg is of
    ;; the form (varname vartype) and `vartype' is a class, then
    ;; that class will be the type symbol.  If not, then it will fall
    ;; under the type `primary' which is a non-specific calling of the
    ;; function.
    (setq firstarg (car args))
    (if (listp firstarg)
	(progn
	  (setq argclass  (nth 1 firstarg))
	  (if (not (class-p argclass))
	      (error "Unknown class type %s in method parameters"
		     (nth 1 firstarg))))
      (if (= key -1)
	  (signal 'wrong-type-argument (list :static 'non-class-arg)))
      ;; generics are higher
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      (setq key (eieio-specialized-key-to-generic-key key)))
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    ;; Put this lambda into the symbol so we can find it
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    (eieiomt-add method code key argclass)
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    )

  (when eieio-optimize-primary-methods-flag
    ;; Optimizing step:
    ;;
    ;; If this method, after this setup, only has primary methods, then
    ;; we can setup the generic that way.
    (if (generic-primary-only-p method)
	;; If there is only one primary method, then we can go one more
	;; optimization step.
	(if (generic-primary-only-one-p method)
	    (eieio-defgeneric-reset-generic-form-primary-only-one method)
	  (eieio-defgeneric-reset-generic-form-primary-only method))
      (eieio-defgeneric-reset-generic-form method)))

  method)

;;; Slot type validation
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;; This is a hideous hack for replacing `typep' from cl-macs, to avoid
;; requiring the CL library at run-time.  It can be eliminated if/when
;; `typep' is merged into Emacs core.
(defun eieio--typep (val type)
  (if (symbolp type)
      (cond ((get type 'cl-deftype-handler)
	     (eieio--typep val (funcall (get type 'cl-deftype-handler))))
	    ((eq type t) t)
	    ((eq type 'null)   (null val))
	    ((eq type 'atom)   (atom val))
	    ((eq type 'float)  (and (numberp val) (not (integerp val))))
	    ((eq type 'real)   (numberp val))
	    ((eq type 'fixnum) (integerp val))
	    ((memq type '(character string-char)) (characterp val))
	    (t
	     (let* ((name (symbol-name type))
		    (namep (intern (concat name "p"))))
	       (if (fboundp namep)
		   (funcall `(lambda () (,namep val)))
		 (funcall `(lambda ()
			     (,(intern (concat name "-p")) val)))))))
    (cond ((get (car type) 'cl-deftype-handler)
	   (eieio--typep val (apply (get (car type) 'cl-deftype-handler)
				    (cdr type))))
	  ((memq (car type) '(integer float real number))
	   (and (eieio--typep val (car type))
		(or (memq (cadr type) '(* nil))
		    (if (consp (cadr type))
			(> val (car (cadr type)))
		      (>= val (cadr type))))
		(or (memq (caddr type) '(* nil))
		    (if (consp (car (cddr type)))
			(< val (caar (cddr type)))
		      (<= val (car (cddr type)))))))
	  ((memq (car type) '(and or not))
	   (eval (cons (car type)
		       (mapcar (lambda (x)
				 `(eieio--typep (quote ,val) (quote ,x)))
			       (cdr type)))))
	  ((memq (car type) '(member member*))
	   (memql val (cdr type)))
	  ((eq (car type) 'satisfies)
	   (funcall `(lambda () (,(cadr type) val))))
	  (t (error "Bad type spec: %s" type)))))

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(defun eieio-perform-slot-validation (spec value)
  "Return non-nil if SPEC does not match VALUE."
  (or (eq spec t)			; t always passes
      (eq value eieio-unbound)		; unbound always passes
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      (eieio--typep value spec)))
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(defun eieio-validate-slot-value (class slot-idx value slot)
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  "Make sure that for CLASS referencing SLOT-IDX, VALUE is valid.
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Checks the :type specifier.
SLOT is the slot that is being checked, and is only used when throwing
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an error."
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  (if eieio-skip-typecheck
      nil
    ;; Trim off object IDX junk added in for the object index.
    (setq slot-idx (- slot-idx 3))
    (let ((st (aref (aref (class-v class) class-public-type) slot-idx)))
      (if (not (eieio-perform-slot-validation st value))
	  (signal 'invalid-slot-type (list class slot st value))))))

(defun eieio-validate-class-slot-value (class slot-idx value slot)
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  "Make sure that for CLASS referencing SLOT-IDX, VALUE is valid.
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Checks the :type specifier.
SLOT is the slot that is being checked, and is only used when throwing
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an error."
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  (if eieio-skip-typecheck
      nil
    (let ((st (aref (aref (class-v class) class-class-allocation-type)
		    slot-idx)))
      (if (not (eieio-perform-slot-validation st value))
	  (signal 'invalid-slot-type (list class slot st value))))))

(defun eieio-barf-if-slot-unbound (value instance slotname fn)
  "Throw a signal if VALUE is a representation of an UNBOUND slot.
INSTANCE is the object being referenced.  SLOTNAME is the offending
slot.  If the slot is ok, return VALUE.
Argument FN is the function calling this verifier."
  (if (and (eq value eieio-unbound) (not eieio-skip-typecheck))
      (slot-unbound instance (object-class instance) slotname fn)
    value))

;;; Get/Set slots in an object.
;;
(defmacro oref (obj slot)
  "Retrieve the value stored in OBJ in the slot named by SLOT.
Slot is the name of the slot when created by `defclass' or the label
created by the :initarg tag."
  `(eieio-oref ,obj (quote ,slot)))

(defun eieio-oref (obj slot)
  "Return the value in OBJ at SLOT in the object vector."
  (if (not (or (eieio-object-p obj) (class-p obj)))
      (signal 'wrong-type-argument (list '(or eieio-object-p class-p) obj)))
  (if (not (symbolp slot))
      (signal 'wrong-type-argument (list 'symbolp slot)))
  (if (class-p obj) (eieio-class-un-autoload obj))
  (let* ((class (if (class-p obj) obj (aref obj object-class)))
	 (c (eieio-slot-name-index class obj slot)))
    (if (not c)
	;; It might be missing because it is a :class allocated slot.
	;; Lets check that info out.
	(if (setq c (eieio-class-slot-name-index class slot))
	    ;; Oref that slot.
	    (aref (aref (class-v class) class-class-allocation-values) c)
	  ;; The slot-missing method is a cool way of allowing an object author
	  ;; to intercept missing slot definitions.  Since it is also the LAST
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	  ;; thing called in this fn, its return value would be retrieved.
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	  (slot-missing obj slot 'oref)
	  ;;(signal 'invalid-slot-name (list (object-name obj) slot))
	  )
      (if (not (eieio-object-p obj))
	  (signal 'wrong-type-argument (list 'eieio-object-p obj)))
      (eieio-barf-if-slot-unbound (aref obj c) obj slot 'oref))))

(defalias 'slot-value 'eieio-oref)
(defalias 'set-slot-value 'eieio-oset)

(defmacro oref-default (obj slot)
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  "Get the default value of OBJ (maybe a class) for SLOT.
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The default value is the value installed in a class with the :initform
tag.  SLOT can be the slot name, or the tag specified by the :initarg
tag in the `defclass' call."
  `(eieio-oref-default ,obj (quote ,slot)))

(defun eieio-oref-default (obj slot)
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  "Do the work for the macro `oref-default' with similar parameters.
Fills in OBJ's SLOT with its default value."
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  (if (not (or (eieio-object-p obj) (class-p obj))) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (if (not (symbolp slot)) (signal 'wrong-type-argument (list 'symbolp slot)))
  (let* ((cl (if (eieio-object-p obj) (aref obj object-class) obj))
	 (c (eieio-slot-name-index cl obj slot)))
    (if (not c)
	;; It might be missing because it is a :class allocated slot.
	;; Lets check that info out.
	(if (setq c
		  (eieio-class-slot-name-index cl slot))
	    ;; Oref that slot.
	    (aref (aref (class-v cl) class-class-allocation-values)
		  c)
	  (slot-missing obj slot 'oref-default)
	  ;;(signal 'invalid-slot-name (list (class-name cl) slot))
	  )
      (eieio-barf-if-slot-unbound
       (let ((val (nth (- c 3) (aref (class-v cl) class-public-d))))
	 (eieio-default-eval-maybe val))
       obj cl 'oref-default))))

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(defsubst eieio-eval-default-p (val)
  "Whether the default value VAL should be evaluated for use."
  (and (consp val) (symbolp (car val)) (fboundp (car val))))

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(defun eieio-default-eval-maybe (val)
  "Check VAL, and return what `oref-default' would provide."
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  (cond
   ;; Is it a function call?  If so, evaluate it.
   ((eieio-eval-default-p val)
    (eval val))
   ;;;; check for quoted things, and unquote them
   ;;((and (consp val) (eq (car val) 'quote))
   ;; (car (cdr val)))
   ;; return it verbatim
   (t val)))
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;;; Object Set macros
;;
(defmacro oset (obj slot value)
  "Set the value in OBJ for slot SLOT to VALUE.
SLOT is the slot name as specified in `defclass' or the tag created
with in the :initarg slot.  VALUE can be any Lisp object."
  `(eieio-oset ,obj (quote ,slot) ,value))

(defun eieio-oset (obj slot value)
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  "Do the work for the macro `oset'.
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Fills in OBJ's SLOT with VALUE."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (if (not (symbolp slot)) (signal 'wrong-type-argument (list 'symbolp slot)))
  (let ((c (eieio-slot-name-index (object-class-fast obj) obj slot)))
    (if (not c)
	;; It might be missing because it is a :class allocated slot.
	;; Lets check that info out.
	(if (setq c
		  (eieio-class-slot-name-index (aref obj object-class) slot))
	    ;; Oset that slot.
	    (progn
	      (eieio-validate-class-slot-value (object-class-fast obj) c value slot)
	      (aset (aref (class-v (aref obj object-class))
			  class-class-allocation-values)
		    c value))
	  ;; See oref for comment on `slot-missing'
	  (slot-missing obj slot 'oset value)
	  ;;(signal 'invalid-slot-name (list (object-name obj) slot))
	  )
      (eieio-validate-slot-value (object-class-fast obj) c value slot)
      (aset obj c value))))

(defmacro oset-default (class slot value)
  "Set the default slot in CLASS for SLOT to VALUE.
The default value is usually set with the :initform tag during class
creation.  This allows users to change the default behavior of classes
after they are created."
  `(eieio-oset-default ,class (quote ,slot) ,value))

(defun eieio-oset-default (class slot value)
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  "Do the work for the macro `oset-default'.
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Fills in the default value in CLASS' in SLOT with VALUE."
  (if (not (class-p class)) (signal 'wrong-type-argument (list 'class-p class)))
  (if (not (symbolp slot)) (signal 'wrong-type-argument (list 'symbolp slot)))
  (let* ((scoped-class class)
	 (c (eieio-slot-name-index class nil slot)))
    (if (not c)
	;; It might be missing because it is a :class allocated slot.
	;; Lets check that info out.
	(if (setq c (eieio-class-slot-name-index class slot))
	    (progn
	      ;; Oref that slot.
	      (eieio-validate-class-slot-value class c value slot)
	      (aset (aref (class-v class) class-class-allocation-values) c
		    value))
	  (signal 'invalid-slot-name (list (class-name class) slot)))
      (eieio-validate-slot-value class c value slot)
      ;; Set this into the storage for defaults.
      (setcar (nthcdr (- c 3) (aref (class-v class) class-public-d))
	      value)
      ;; Take the value, and put it into our cache object.
      (eieio-oset (aref (class-v class) class-default-object-cache)
		  slot value)
      )))

;;; Handy CLOS macros
;;
(defmacro with-slots (spec-list object &rest body)
  "Bind SPEC-LIST lexically to slot values in OBJECT, and execute BODY.
This establishes a lexical environment for referring to the slots in
the instance named by the given slot-names as though they were
variables.  Within such a context the value of the slot can be
specified by using its slot name, as if it were a lexically bound
variable.  Both setf and setq can be used to set the value of the
slot.

SPEC-LIST is of a form similar to `let'.  For example:

  ((VAR1 SLOT1)
    SLOT2
    SLOTN
   (VARN+1 SLOTN+1))

Where each VAR is the local variable given to the associated
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SLOT.  A slot specified without a variable name is given a
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variable name of the same name as the slot."
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  (declare (indent 2))
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  ;; Transform the spec-list into a symbol-macrolet spec-list.
  (let ((mappings (mapcar (lambda (entry)
			    (let ((var  (if (listp entry) (car entry) entry))
				  (slot (if (listp entry) (cadr entry) entry)))
			      (list var `(slot-value ,object ',slot))))
			  spec-list)))
    (append (list 'symbol-macrolet mappings)
	    body)))

;;; Simple generators, and query functions.  None of these would do
;;  well embedded into an object.
;;
(defmacro object-class-fast (obj) "Return the class struct defining OBJ with no check."
  `(aref ,obj object-class))

(defun class-name (class) "Return a Lisp like symbol name for CLASS."
  (if (not (class-p class)) (signal 'wrong-type-argument (list 'class-p class)))
  ;; I think this is supposed to return a symbol, but to me CLASS is a symbol,
  ;; and I wanted a string.  Arg!
  (format "#<class %s>" (symbol-name class)))

(defun object-name (obj &optional extra)
  "Return a Lisp like symbol string for object OBJ.
If EXTRA, include that in the string returned to represent the symbol."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (format "#<%s %s%s>" (symbol-name (object-class-fast obj))
	  (aref obj object-name) (or extra "")))

(defun object-name-string (obj) "Return a string which is OBJ's name."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (aref obj object-name))

(defun object-set-name-string (obj name) "Set the string which is OBJ's NAME."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (if (not (stringp name)) (signal 'wrong-type-argument (list 'stringp name)))
  (aset obj object-name name))

(defun object-class (obj) "Return the class struct defining OBJ."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (object-class-fast obj))
(defalias 'class-of 'object-class)

(defun object-class-name (obj) "Return a Lisp like symbol name for OBJ's class."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (class-name (object-class-fast obj)))

(defmacro class-parents-fast (class) "Return parent classes to CLASS with no check."
  `(aref (class-v ,class) class-parent))

(defun class-parents (class)
  "Return parent classes to CLASS.  (overload of variable).

The CLOS function `class-direct-superclasses' is aliased to this function."
  (if (not (class-p class)) (signal 'wrong-type-argument (list 'class-p class)))
  (class-parents-fast class))

(defmacro class-children-fast (class) "Return child classes to CLASS with no check."
  `(aref (class-v ,class) class-children))

(defun class-children (class)
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"Return child classes to CLASS.
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The CLOS function `class-direct-subclasses' is aliased to this function."
  (if (not (class-p class)) (signal 'wrong-type-argument (list 'class-p class)))
  (class-children-fast class))

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(defun eieio-c3-candidate (class remaining-inputs)
  "Returns CLASS if it can go in the result now, otherwise nil"
  ;; Ensure CLASS is not in any position but the first in any of the
  ;; element lists of REMAINING-INPUTS.
  (and (not (let ((found nil))
	      (while (and remaining-inputs (not found))
		(setq found (member class (cdr (car remaining-inputs)))
		      remaining-inputs (cdr remaining-inputs)))
	      found))
       class))

(defun eieio-c3-merge-lists (reversed-partial-result remaining-inputs)
  "Merge REVERSED-PARTIAL-RESULT REMAINING-INPUTS in a consistent order, if possible.
If a consistent order does not exist, signal an error."
  (if (let ((tail remaining-inputs)
	    (found nil))
	(while (and tail (not found))
	  (setq found (car tail) tail (cdr tail)))
	(not found))
      ;; If all remaining inputs are empty lists, we are done.
      (nreverse reversed-partial-result)
    ;; Otherwise, we try to find the next element of the result. This
    ;; is achieved by considering the first element of each
    ;; (non-empty) input list and accepting a candidate if it is
    ;; consistent with the rests of the input lists.
    (let* ((found nil)
	   (tail remaining-inputs)
	   (next (progn
		   (while (and tail (not found))
		     (setq found (and (car tail)
				      (eieio-c3-candidate (caar tail)
							  remaining-inputs))
			   tail (cdr tail)))
		   found)))
      (if next
	  ;; The graph is consistent so far, add NEXT to result and
	  ;; merge input lists, dropping NEXT from their heads where
	  ;; applicable.
	  (eieio-c3-merge-lists
	   (cons next reversed-partial-result)
	   (mapcar (lambda (l) (if (eq (first l) next) (rest l) l))
		   remaining-inputs))
	;; The graph is inconsistent, give up
	(signal 'inconsistent-class-hierarchy (list remaining-inputs))))))

(defun eieio-class-precedence-dfs (class)
  "Return all parents of CLASS in depth-first order."
  (let* ((parents (class-parents-fast class))
	 (classes (copy-sequence
		   (apply #'append
			  (list class)
			  (or
			   (mapcar
			    (lambda (parent)
			      (cons parent
				    (eieio-class-precedence-dfs parent)))
			    parents)
			   '((eieio-default-superclass))))))
	 (tail classes))
    ;; Remove duplicates.
    (while tail
      (setcdr tail (delq (car tail) (cdr tail)))
      (setq tail (cdr tail)))
    classes))

(defun eieio-class-precedence-bfs (class)
  "Return all parents of CLASS in breadth-first order."
  (let ((result)
	(queue (or (class-parents-fast class)
		   '(eieio-default-superclass))))
    (while queue
      (let ((head (pop queue)))
	(unless (member head result)
	  (push head result)
	  (unless (eq head 'eieio-default-superclass)
	    (setq queue (append queue (or (class-parents-fast head)
					  '(eieio-default-superclass))))))))
    (cons class (nreverse result)))
  )

(defun eieio-class-precedence-c3 (class)
  "Return all parents of CLASS in c3 order."
  (let ((parents (class-parents-fast class)))
    (eieio-c3-merge-lists
     (list class)
     (append
      (or
       (mapcar
	(lambda (x)
	  (eieio-class-precedence-c3 x))
	parents)
       '((eieio-default-superclass)))
      (list parents))))
  )

(defun class-precedence-list (class)
  "Return (transitively closed) list of parents of CLASS.
The order, in which the parents are returned depends on the
method invocation orders of the involved classes."
  (if (or (null class) (eq class 'eieio-default-superclass))
      nil
    (case (class-method-invocation-order class)
      (:depth-first
       (eieio-class-precedence-dfs class))
      (:breadth-first
       (eieio-class-precedence-bfs class))
      (:c3
       (eieio-class-precedence-c3 class))))
  )

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;; Official CLOS functions.
(defalias 'class-direct-superclasses 'class-parents)
(defalias 'class-direct-subclasses 'class-children)

(defmacro class-parent-fast (class) "Return first parent class to CLASS with no check."
  `(car (class-parents-fast ,class)))

(defmacro class-parent (class) "Return first parent class to CLASS.  (overload of variable)."
  `(car (class-parents ,class)))

(defmacro same-class-fast-p (obj class) "Return t if OBJ is of class-type CLASS with no error checking."
  `(eq (aref ,obj object-class) ,class))

(defun same-class-p (obj class) "Return t if OBJ is of class-type CLASS."
  (if (not (class-p class)) (signal 'wrong-type-argument (list 'class-p class)))
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  (same-class-fast-p obj class))

(defun object-of-class-p (obj class)
  "Return non-nil if OBJ is an instance of CLASS or CLASS' subclasses."
  (if (not (eieio-object-p obj)) (signal 'wrong-type-argument (list 'eieio-object-p obj)))
  ;; class will be checked one layer down
  (child-of-class-p (aref obj object-class) class))
;; Backwards compatibility
(defalias 'obj-of-class-p 'object-of-class-p)

(defun child-of-class-p (child class)
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  "Return non-nil if CHILD class is a subclass of CLASS."
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