Commit 82f84fa3 authored by Chong Yidong's avatar Chong Yidong

Update the URL library manual.

* doc/misc/url.texi (Introduction): Rename from Getting Started.
Rewrite the introduction.
(URI Parsing): Rewrite.  Omit the obsolete attributes slot.
parent fedb154e
2012-11-08 Chong Yidong <>
* url.texi (Introduction): Rename from Getting Started. Rewrite
the introduction.
(URI Parsing): Rewrite. Omit the obsolete attributes slot.
2012-11-07 Glenn Morris <>
* cl.texi (Obsolete Setf Customization):
......@@ -18,7 +18,7 @@
@end direntry
This file documents the Emacs Lisp URL loading package.
This file documents @code{url} Emacs Lisp library.
Copyright @copyright{} 1993-1999, 2002, 2004-2012 Free Software Foundation, Inc.
......@@ -57,7 +57,8 @@ developing GNU and promoting software freedom.''
@end ifnottex
* Getting Started:: Preparing your program to use URLs.
* Introduction:: About the @code{url} library.
* URI Parsing:: Parsing (and unparsing) URIs.
* Retrieving URLs:: How to use this package to retrieve a URL.
* Supported URL Types:: Descriptions of URL types currently supported.
* Defining New URLs:: How to define a URL loader for a new protocol.
......@@ -70,93 +71,132 @@ developing GNU and promoting software freedom.''
* Concept Index::
@end menu
@node Getting Started
@chapter Getting Started
@cindex URLs, definition
@cindex URIs
@node Introduction
@chapter Introduction
@cindex URL
@cindex URI
@cindex uniform resource identifier
@cindex uniform resource locator
@dfn{Uniform Resource Locators} (URLs) are a specific form of
@dfn{Uniform Resource Identifiers} (URI) described in RFC 2396 which
updates RFC 1738 and RFC 1808. RFC 2016 defines uniform resource
A @dfn{Uniform Resource Identifier} (URI) is a specially-formatted
name, such as an Internet address, which identifies some name or
resource. The format of URIs is described in RFC 3986, which updates
and replaces the earlier RFCs 2732, 2396, 1808, and 1738. A
@dfn{Uniform Resource Locator} (URL) is an older but still-common
term, which basically refers to a URI corresponding to a resource
which can be accessed over a network.
URIs have the form @var{scheme}:@var{scheme-specific-part}, where the
@var{scheme}s supported by this library are described below.
@xref{Supported URL Types}.
FTP, NFS, HTTP, HTTPS, @code{rlogin}, @code{telnet}, tn3270,
IRC and gopher URLs all have the form
Here are some examples of URIs (taken from RFC 3986):
@end example
where @samp{@r{[}} and @samp{@r{]}} delimit optional parts.
@var{userinfo} sometimes takes the form @var{username}:@var{password}
but you should beware of the security risks of sending cleartext
passwords. @var{hostname} may be a domain name or a dotted decimal
address. If the @samp{:@var{port}} is omitted then the library will
use the ``well known'' port for that service when accessing URLs. With
the possible exception of @code{telnet}, it is rare for ports to be
specified, and it is possible using a non-standard port may have
undesired consequences if a different service is listening on that
port (e.g., an HTTP URL specifying the SMTP port can cause mail to be
sent). @c , but @xref{Other Variables, url-bad-port-list}.
The meaning of the @var{path} component depends on the service.
* Configuration::
* Parsed URLs:: URLs are parsed into vector structures.
@end menu
@node Configuration
@section Configuration
This manual describes the @code{url} library, an Emacs Lisp library
for parsing URIs and retrieving the resources to which they refer.
(The library is so-named due to historical reasons; nowadays, the
``URI'' terminology is regarded as the more general one, and ``URL''
is technically obsolete despite its widespread vernacular usage.)
@defvar url-configuration-directory
@cindex @file{~/.url}
@cindex configuration files
The directory in which URL configuration files, the cache etc.,
reside. The old default was @file{~/.url}, and this directory
is still used if it exists. The new default is a @file{url/}
directory in @code{user-emacs-directory}, which is normally
The value of this variable specifies the name of the directory in
which the @code{url} library stores its various configuration files,
cache files, etc.
The default value specifies a subdirectory named @file{url/} in the
standard Emacs user data directory specified by the variable
@code{user-emacs-directory} (normally @file{~/.emacs.d}). However,
the old default was @file{~/.url}, and this directory is used instead
if it exists.
@end defvar
@node Parsed URLs
@section Parsed URLs
@cindex parsed URLs
The library functions typically operate on @dfn{parsed} versions of
URLs. These are actually CL structures (vectors) of the form:
@node URI Parsing
@chapter URI Parsing
A URI consists of several @dfn{components}, each having a different
meaning. For example, the URI
[cl-struct-url @var{type} @var{user} @var{password} @var{host} @var{port} @var{filename} @var{target} @var{attributes} @var{fullness} @var{use-cookies}]
@end example
@noindent where
@table @var
specifies the scheme component @samp{http}, the hostname component
@samp{}, and the path component @samp{/software/emacs/}.
@cindex parsed URIs
The URI format is specified by RFC 3986. The @code{url} library
provides the Lisp function @code{url-generic-parse-url}, a
standard-compliant URI parser, as well as the unparser
@defun url-generic-parse-url url
This function returns a parsed version of the string @var{url}.
@end defun
@defun url-recreate-url uri
@cindex unparsing URLs
Given a parsed URI, this function returns a corresponding URI string.
@end defun
@cindex parsed URI
The return value of @code{url-generic-parse-url}, and the argument
expected by @code{url-recreate-url}, is a @dfn{parsed URI}, in the
form of a CL structure whose slots hold the various components of the
URI. @xref{top,the CL Manual,,cl,GNU Emacs Common Lisp Emulation},
for details about CL structures. Most of the other functions in the
@code{url} library act on parsed URIs. Each parsed URI structure
contains the following slots:
@table @code
@item type
is the type of the URL scheme, e.g., @code{http}
The URI scheme (a string, e.g.@: @code{http}). @xref{Supported URL
Types}, for a list of schemes that the @code{url} library knows how to
process. This slot can also be @code{nil}, if the URI is not fully
@item user
is the username associated with it, or @code{nil};
The user name (a string), or @code{nil}.
@item password
is the user password associated with it, or @code{nil};
The user password (a string), or @code{nil}. The use of this URI
component is strongly discouraged; nowadays, passwords are transmitted
by other means, not as part of a URI.
@item host
is the host name associated with it, or @code{nil};
The host name (a string), or @code{nil}. If present, this is
typically a domain name or IP address.
@item port
is the port number associated with it, or @code{nil};
The port number (an integer), or @code{nil}. Omitting this component
usually means to use the ``standard'' port associated with the URI
@item filename
is the ``file'' part of it, or @code{nil}. This doesn't necessarily
actually refer to a file;
The combination of the ``path'' and ``query'' components of the URI (a
string), or @code{nil}. If the query component is present, it is the
substring following the first @samp{?} character, and the path
component is the substring before the @samp{?}. The meaning of these
components depends on the service; they do not necessarily refer to a
file on a disk.
@item target
is the target part, or @code{nil};
@item attributes
is the attributes associated with it, or @code{nil};
The fragment component (a string), or @code{nil}. The fragment
component specifies a ``secondary resource'', such as a section of a
@item fullness
is @code{t} for a fully-specified URL, with a host part indicated by
@samp{//} after the scheme part.
@item use-cookies
is @code{nil} to neither send or store cookies to the server, @code{t}
This is @code{t} if the URI is fully specified, i.e.@: the
hierarchical components of the URI (the hostname and/or username
and/or password) are preceded by @samp{//}.
@end table
@findex url-type
......@@ -168,30 +208,18 @@ otherwise.
@findex url-target
@findex url-attributes
@findex url-fullness
These attributes have accessors named @code{url-@var{part}}, where
@var{part} is the name of one of the elements above, e.g.,
@code{url-host}. These attributes can be set with the same accessors
using @code{setf}:
The above slots have accessors named @code{url-@var{part}}, where
@var{part} is the slot name. For example, the accessor for the
@code{host} slot is the function @code{url-host}. The @code{url-port}
accessor returns the default port for the URI scheme if the parsed
URI's @var{port} slot is @code{nil}.
The slots can be set using @code{setf}. For example:
(setf (url-port url) 80)
@end example
If @var{port} is @var{nil}, @code{url-port} returns the default port
of the protocol.
There are functions for parsing and unparsing between the string and
vector forms.
@defun url-generic-parse-url url
Return a parsed version of the string @var{url}.
@end defun
@defun url-recreate-url url
@cindex unparsing URLs
Recreates a URL string from the parsed @var{url}.
@end defun
@node Retrieving URLs
@chapter Retrieving URLs
......@@ -454,7 +454,9 @@ specifying URL types which should be converted to remote file names at
the FFAP prompt. The default is now '("ftp").
** Generic-x
`javascript-generic-mode' is now an obsolete alias for `js-mode'.
*** `javascript-generic-mode' is now an obsolete alias for `js-mode'.
** Ibuffer
......@@ -531,6 +533,7 @@ python-send-string | python-shell-send-string
python-switch-to-python | python-shell-switch-to-shell
python-describe-symbol | python-eldoc-at-point
** reStructuredText mode
*** Rebind nearly all keys making room for more keys and complying
......@@ -561,6 +564,7 @@ the experience for Sphinx users.
*** Support `imenu' and `which-func'.
** SH Script mode
*** Pairing of parens/quotes uses electric-pair-mode instead of skeleton-pair.
......@@ -575,6 +579,7 @@ the experience for Sphinx users.
for a new asynchronous shell command when the default output buffer
`*Async Shell Command*' is already taken by another running command.
** SQL Mode
*** DB2 added `sql-db2-escape-newlines'
......@@ -605,7 +610,7 @@ definitions. See the manual for details.
*** Remote processes are now supported also on remote Windows host.
** URL
*** Structs made by `url-generic-parse-url' have nil `attributes' slot.
Previously, this slot stored semicolon-separated attribute-value pairs
appended to some imap URLs, but this is not compatible with RFC 3986.
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