Commit 719ad593 authored by Philipp Stephani's avatar Philipp Stephani

Promote function type aliases to the public module API.

Previously module authors had to define type aliases for module
functions and finalizers themselves.  This commit adds and documents
aliases so that this is no longer necessary.

* src/emacs-module.h.in: Add 'emacs_function' and 'emacs_finalizer'
type aliases.

* src/emacs-module.c: Remove old 'emacs_subr' and 'emacs_finalizer'
type aliases.
(struct Lisp_Module_Function, module_make_function): Switch from
'emacs_subr' to 'emacs_function'.

* doc/lispref/internals.texi (Module Functions): Document and use
'emacs_function' type alias.
(Module Values): Document 'emacs_finalizer' type alias.

* etc/NEWS: Mention change.
parent 639fb50e
......@@ -1314,7 +1314,8 @@ subsection describes how to write such @dfn{module functions}.
A module function has the following general form and signature:
@deftypefn Function emacs_value module_func (emacs_env *@var{env}, ptrdiff_t @var{nargs}, emacs_value *@var{args}, void *@var{data})
@deftypefn Function emacs_value emacs_function (emacs_env *@var{env}, ptrdiff_t @var{nargs}, emacs_value *@var{args}, void *@var{data})
@tindex emacs_function
The @var{env} argument provides a pointer to the @acronym{API}
environment, needed to access Emacs objects and functions. The
@var{nargs} argument is the required number of arguments, which can be
......@@ -1323,7 +1324,7 @@ of the argument number), and @var{args} is a pointer to the array of
the function arguments. The argument @var{data} points to additional
data required by the function, which was arranged when
@code{make_function} (see below) was called to create an Emacs
function from @code{module_func}.
function from @code{emacs_function}.
Module functions use the type @code{emacs_value} to communicate Lisp
objects between Emacs and the module (@pxref{Module Values}). The
......@@ -1338,6 +1339,10 @@ However, if the user typed @kbd{C-g}, or if the module function or its
callees signaled an error or exited nonlocally (@pxref{Module
Nonlocal}), Emacs will ignore the returned value and quit or throw as
it does when Lisp code encounters the same situations.
The header @file{emacs-module.h} provides the type
@code{emacs_function} as an alias type for a function pointer to a
module function.
@end deftypefn
After writing your C code for a module function, you should make a
......@@ -1348,11 +1353,11 @@ normally done in the module initialization function (@pxref{module
initialization function}), after verifying the @acronym{API}
compatibility.
@deftypefn Function emacs_value make_function (emacs_env *@var{env}, ptrdiff_t @var{min_arity}, ptrdiff_t @var{max_arity}, subr @var{func}, const char *@var{docstring}, void *@var{data})
@deftypefn Function emacs_value make_function (emacs_env *@var{env}, ptrdiff_t @var{min_arity}, ptrdiff_t @var{max_arity}, emacs_function @var{func}, const char *@var{docstring}, void *@var{data})
@vindex emacs_variadic_function
This returns an Emacs function created from the C function @var{func},
whose signature is as described for @code{module_func} above (assumed
here to be @code{typedef}'ed as @code{subr}). The arguments
whose signature is as described for @code{emacs_function} above.
The arguments
@var{min_arity} and @var{max_arity} specify the minimum and maximum
number of arguments that @var{func} can accept. The @var{max_arity}
argument can have the special value @code{emacs_variadic_function},
......@@ -1844,6 +1849,12 @@ represented by @var{arg} to be @var{fin}. If @var{fin} is a
finalizer.
@end deftypefn
@deftypefun void emacs_finalizer (void *@var{ptr})
The header @file{emacs-module.h} provides the type
@code{emacs_finalizer} as a type alias for an Emacs finalizer
function.
@end deftypefun
@node Module Misc
@subsection Miscellaneous Convenience Functions for Modules
......
......@@ -45,6 +45,10 @@ applies, and please also update docstrings as needed.
* Lisp Changes in Emacs 28.1
** The module header 'emacs-module.h' now contains type aliases
'emacs_function' and 'emacs_finalizer' for module functions and
finalizers, respectively.
* Changes in Emacs 28.1 on Non-Free Operating Systems
......
......@@ -122,12 +122,6 @@ To add a new module function, proceed as follows:
/* Function prototype for the module init function. */
typedef int (*emacs_init_function) (struct emacs_runtime *);
/* Function prototype for module user-pointer finalizers. These
should not throw C++ exceptions, so emacs-module.h declares the
corresponding interfaces with EMACS_NOEXCEPT. There is only C code
in this module, though, so this constraint is not enforced here. */
typedef void (*emacs_finalizer) (void *);
/* Memory management. */
......@@ -466,10 +460,6 @@ module_non_local_exit_throw (emacs_env *env, emacs_value tag, emacs_value value)
value_to_lisp (value));
}
/* Function prototype for the module Lisp functions. */
typedef emacs_value (*emacs_subr) (emacs_env *, ptrdiff_t,
emacs_value *, void *);
/* Module function. */
/* A function environment is an auxiliary structure returned by
......@@ -486,7 +476,7 @@ struct Lisp_Module_Function
/* Fields ignored by GC. */
ptrdiff_t min_arity, max_arity;
emacs_subr subr;
emacs_function subr;
void *data;
} GCALIGNED_STRUCT;
......@@ -505,7 +495,7 @@ allocate_module_function (void)
static emacs_value
module_make_function (emacs_env *env, ptrdiff_t min_arity, ptrdiff_t max_arity,
emacs_subr func, const char *docstring, void *data)
emacs_function func, const char *docstring, void *data)
{
MODULE_FUNCTION_BEGIN (NULL);
......
......@@ -78,6 +78,21 @@ struct emacs_runtime
EMACS_ATTRIBUTE_NONNULL(1);
};
/* Type aliases for function pointer types used in the module API.
Note that we don't use these aliases directly in the API to be able
to mark the function arguments as 'noexcept' before C++20.
However, users can use them if they want. */
/* Function prototype for the module Lisp functions. These must not
throw C++ exceptions. */
typedef emacs_value (*emacs_function) (emacs_env *env, ptrdiff_t nargs,
emacs_value *args,
void *data)
EMACS_NOEXCEPT EMACS_ATTRIBUTE_NONNULL (1);
/* Function prototype for module user-pointer finalizers. These must
not throw C++ exceptions. */
typedef void (*emacs_finalizer) (void *data) EMACS_NOEXCEPT;
/* Possible Emacs function call outcomes. */
enum emacs_funcall_exit
......
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