@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 2002, 2003, 2004,
+@c 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/intro
-@node Copying, Introduction, Top, Top
+@node Introduction, Lisp Data Types, Top, Top
@comment node-name, next, previous, up
-@unnumbered GNU GENERAL PUBLIC LICENSE
-@center Version 2, June 1991
-
-@display
-Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
-59 Temple Place, Suite 330, Boston, MA 02111, USA
-
-Everyone is permitted to copy and distribute verbatim copies
-of this license document, but changing it is not allowed.
-@end display
-
-@unnumberedsec Preamble
-
- The licenses for most software are designed to take away your
-freedom to share and change it. By contrast, the GNU General Public
-License is intended to guarantee your freedom to share and change free
-software---to make sure the software is free for all its users. This
-General Public License applies to most of the Free Software
-Foundation's software and to any other program whose authors commit to
-using it. (Some other Free Software Foundation software is covered by
-the GNU Library General Public License instead.) You can apply it to
-your programs, too.
-
- When we speak of free software, we are referring to freedom, not
-price. Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-this service if you wish), that you receive source code or can get it
-if you want it, that you can change the software or use pieces of it
-in new free programs; and that you know you can do these things.
-
- To protect your rights, we need to make restrictions that forbid
-anyone to deny you these rights or to ask you to surrender the rights.
-These restrictions translate to certain responsibilities for you if you
-distribute copies of the software, or if you modify it.
-
- For example, if you distribute copies of such a program, whether
-gratis or for a fee, you must give the recipients all the rights that
-you have. You must make sure that they, too, receive or can get the
-source code. And you must show them these terms so they know their
-rights.
-
- We protect your rights with two steps: (1) copyright the software, and
-(2) offer you this license which gives you legal permission to copy,
-distribute and/or modify the software.
-
- Also, for each author's protection and ours, we want to make certain
-that everyone understands that there is no warranty for this free
-software. If the software is modified by someone else and passed on, we
-want its recipients to know that what they have is not the original, so
-that any problems introduced by others will not reflect on the original
-authors' reputations.
-
- Finally, any free program is threatened constantly by software
-patents. We wish to avoid the danger that redistributors of a free
-program will individually obtain patent licenses, in effect making the
-program proprietary. To prevent this, we have made it clear that any
-patent must be licensed for everyone's free use or not licensed at all.
-
- The precise terms and conditions for copying, distribution and
-modification follow.
-
-@iftex
-@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-@end iftex
-@ifnottex
-@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
-@end ifnottex
-
-@enumerate 0
-@item
-This License applies to any program or other work which contains
-a notice placed by the copyright holder saying it may be distributed
-under the terms of this General Public License. The ``Program'', below,
-refers to any such program or work, and a ``work based on the Program''
-means either the Program or any derivative work under copyright law:
-that is to say, a work containing the Program or a portion of it,
-either verbatim or with modifications and/or translated into another
-language. (Hereinafter, translation is included without limitation in
-the term ``modification''.) Each licensee is addressed as ``you''.
-
-Activities other than copying, distribution and modification are not
-covered by this License; they are outside its scope. The act of
-running the Program is not restricted, and the output from the Program
-is covered only if its contents constitute a work based on the
-Program (independent of having been made by running the Program).
-Whether that is true depends on what the Program does.
-
-@item
-You may copy and distribute verbatim copies of the Program's
-source code as you receive it, in any medium, provided that you
-conspicuously and appropriately publish on each copy an appropriate
-copyright notice and disclaimer of warranty; keep intact all the
-notices that refer to this License and to the absence of any warranty;
-and give any other recipients of the Program a copy of this License
-along with the Program.
-
-You may charge a fee for the physical act of transferring a copy, and
-you may at your option offer warranty protection in exchange for a fee.
-
-@item
-You may modify your copy or copies of the Program or any portion
-of it, thus forming a work based on the Program, and copy and
-distribute such modifications or work under the terms of Section 1
-above, provided that you also meet all of these conditions:
-
-@enumerate a
-@item
-You must cause the modified files to carry prominent notices
-stating that you changed the files and the date of any change.
-
-@item
-You must cause any work that you distribute or publish, that in
-whole or in part contains or is derived from the Program or any
-part thereof, to be licensed as a whole at no charge to all third
-parties under the terms of this License.
-
-@item
-If the modified program normally reads commands interactively
-when run, you must cause it, when started running for such
-interactive use in the most ordinary way, to print or display an
-announcement including an appropriate copyright notice and a
-notice that there is no warranty (or else, saying that you provide
-a warranty) and that users may redistribute the program under
-these conditions, and telling the user how to view a copy of this
-License. (Exception: if the Program itself is interactive but
-does not normally print such an announcement, your work based on
-the Program is not required to print an announcement.)
-@end enumerate
-
-These requirements apply to the modified work as a whole. If
-identifiable sections of that work are not derived from the Program,
-and can be reasonably considered independent and separate works in
-themselves, then this License, and its terms, do not apply to those
-sections when you distribute them as separate works. But when you
-distribute the same sections as part of a whole which is a work based
-on the Program, the distribution of the whole must be on the terms of
-this License, whose permissions for other licensees extend to the
-entire whole, and thus to each and every part regardless of who wrote it.
-
-Thus, it is not the intent of this section to claim rights or contest
-your rights to work written entirely by you; rather, the intent is to
-exercise the right to control the distribution of derivative or
-collective works based on the Program.
-
-In addition, mere aggregation of another work not based on the Program
-with the Program (or with a work based on the Program) on a volume of
-a storage or distribution medium does not bring the other work under
-the scope of this License.
-
-@item
-You may copy and distribute the Program (or a work based on it,
-under Section 2) in object code or executable form under the terms of
-Sections 1 and 2 above provided that you also do one of the following:
-
-@enumerate a
-@item
-Accompany it with the complete corresponding machine-readable
-source code, which must be distributed under the terms of Sections
-1 and 2 above on a medium customarily used for software interchange; or,
-
-@item
-Accompany it with a written offer, valid for at least three
-years, to give any third party, for a charge no more than your
-cost of physically performing source distribution, a complete
-machine-readable copy of the corresponding source code, to be
-distributed under the terms of Sections 1 and 2 above on a medium
-customarily used for software interchange; or,
-
-@item
-Accompany it with the information you received as to the offer
-to distribute corresponding source code. (This alternative is
-allowed only for noncommercial distribution and only if you
-received the program in object code or executable form with such
-an offer, in accord with Subsection b above.)
-@end enumerate
-
-The source code for a work means the preferred form of the work for
-making modifications to it. For an executable work, complete source
-code means all the source code for all modules it contains, plus any
-associated interface definition files, plus the scripts used to
-control compilation and installation of the executable. However, as a
-special exception, the source code distributed need not include
-anything that is normally distributed (in either source or binary
-form) with the major components (compiler, kernel, and so on) of the
-operating system on which the executable runs, unless that component
-itself accompanies the executable.
-
-If distribution of executable or object code is made by offering
-access to copy from a designated place, then offering equivalent
-access to copy the source code from the same place counts as
-distribution of the source code, even though third parties are not
-compelled to copy the source along with the object code.
-
-@item
-You may not copy, modify, sublicense, or distribute the Program
-except as expressly provided under this License. Any attempt
-otherwise to copy, modify, sublicense or distribute the Program is
-void, and will automatically terminate your rights under this License.
-However, parties who have received copies, or rights, from you under
-this License will not have their licenses terminated so long as such
-parties remain in full compliance.
-
-@item
-You are not required to accept this License, since you have not
-signed it. However, nothing else grants you permission to modify or
-distribute the Program or its derivative works. These actions are
-prohibited by law if you do not accept this License. Therefore, by
-modifying or distributing the Program (or any work based on the
-Program), you indicate your acceptance of this License to do so, and
-all its terms and conditions for copying, distributing or modifying
-the Program or works based on it.
-
-@item
-Each time you redistribute the Program (or any work based on the
-Program), the recipient automatically receives a license from the
-original licensor to copy, distribute or modify the Program subject to
-these terms and conditions. You may not impose any further
-restrictions on the recipients' exercise of the rights granted herein.
-You are not responsible for enforcing compliance by third parties to
-this License.
-
-@item
-If, as a consequence of a court judgment or allegation of patent
-infringement or for any other reason (not limited to patent issues),
-conditions are imposed on you (whether by court order, agreement or
-otherwise) that contradict the conditions of this License, they do not
-excuse you from the conditions of this License. If you cannot
-distribute so as to satisfy simultaneously your obligations under this
-License and any other pertinent obligations, then as a consequence you
-may not distribute the Program at all. For example, if a patent
-license would not permit royalty-free redistribution of the Program by
-all those who receive copies directly or indirectly through you, then
-the only way you could satisfy both it and this License would be to
-refrain entirely from distribution of the Program.
-
-If any portion of this section is held invalid or unenforceable under
-any particular circumstance, the balance of the section is intended to
-apply and the section as a whole is intended to apply in other
-circumstances.
-
-It is not the purpose of this section to induce you to infringe any
-patents or other property right claims or to contest validity of any
-such claims; this section has the sole purpose of protecting the
-integrity of the free software distribution system, which is
-implemented by public license practices. Many people have made
-generous contributions to the wide range of software distributed
-through that system in reliance on consistent application of that
-system; it is up to the author/donor to decide if he or she is willing
-to distribute software through any other system and a licensee cannot
-impose that choice.
-
-This section is intended to make thoroughly clear what is believed to
-be a consequence of the rest of this License.
-
-@item
-If the distribution and/or use of the Program is restricted in
-certain countries either by patents or by copyrighted interfaces, the
-original copyright holder who places the Program under this License
-may add an explicit geographical distribution limitation excluding
-those countries, so that distribution is permitted only in or among
-countries not thus excluded. In such case, this License incorporates
-the limitation as if written in the body of this License.
-
-@item
-The Free Software Foundation may publish revised and/or new versions
-of the General Public License from time to time. Such new versions will
-be similar in spirit to the present version, but may differ in detail to
-address new problems or concerns.
-
-Each version is given a distinguishing version number. If the Program
-specifies a version number of this License which applies to it and ``any
-later version'', you have the option of following the terms and conditions
-either of that version or of any later version published by the Free
-Software Foundation. If the Program does not specify a version number of
-this License, you may choose any version ever published by the Free Software
-Foundation.
-
-@item
-If you wish to incorporate parts of the Program into other free
-programs whose distribution conditions are different, write to the author
-to ask for permission. For software which is copyrighted by the Free
-Software Foundation, write to the Free Software Foundation; we sometimes
-make exceptions for this. Our decision will be guided by the two goals
-of preserving the free status of all derivatives of our free software and
-of promoting the sharing and reuse of software generally.
-
-@iftex
-@heading NO WARRANTY
-@end iftex
-@ifnottex
-@center NO WARRANTY
-@end ifnottex
-
-@item
-BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
-FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW@. EXCEPT WHEN
-OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
-PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
-OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
-MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE@. THE ENTIRE RISK AS
-TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU@. SHOULD THE
-PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
-REPAIR OR CORRECTION.
-
-@item
-IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
-WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
-REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
-INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
-OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
-TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
-YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
-PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
-POSSIBILITY OF SUCH DAMAGES.
-@end enumerate
-
-@iftex
-@heading END OF TERMS AND CONDITIONS
-@end iftex
-@ifnottex
-@center END OF TERMS AND CONDITIONS
-@end ifnottex
-
-@page
-@unnumberedsec How to Apply These Terms to Your New Programs
-
- If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these terms.
-
- To do so, attach the following notices to the program. It is safest
-to attach them to the start of each source file to most effectively
-convey the exclusion of warranty; and each file should have at least
-the ``copyright'' line and a pointer to where the full notice is found.
-
-@smallexample
-@var{one line to give the program's name and an idea of what it does.}
-Copyright (C) @var{year} @var{name of author}
-
-This program 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 2
-of the License, or (at your option) any later version.
-
-This program 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 this program; if not, write to the Free Software
-Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
-@end smallexample
-
-Also add information on how to contact you by electronic and paper mail.
-
-If the program is interactive, make it output a short notice like this
-when it starts in an interactive mode:
-
-@smallexample
-Gnomovision version 69, Copyright (C) @var{year} @var{name of author}
-Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
-type `show w'. This is free software, and you are welcome
-to redistribute it under certain conditions; type `show c'
-for details.
-@end smallexample
-
-The hypothetical commands @samp{show w} and @samp{show c} should show
-the appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than @samp{show w} and
-@samp{show c}; they could even be mouse-clicks or menu items---whatever
-suits your program.
-
-You should also get your employer (if you work as a programmer) or your
-school, if any, to sign a ``copyright disclaimer'' for the program, if
-necessary. Here is a sample; alter the names:
-
-@smallexample
-@group
-Yoyodyne, Inc., hereby disclaims all copyright
-interest in the program `Gnomovision'
-(which makes passes at compilers) written
-by James Hacker.
-
-@var{signature of Ty Coon}, 1 April 1989
-Ty Coon, President of Vice
-@end group
-@end smallexample
-
-This General Public License does not permit incorporating your program into
-proprietary programs. If your program is a subroutine library, you may
-consider it more useful to permit linking proprietary applications with the
-library. If this is what you want to do, use the GNU Library General
-Public License instead of this License.
-
-@node Introduction, Lisp Data Types, Copying, Top
@chapter Introduction
Most of the GNU Emacs text editor is written in the programming
chapters describe features that are peculiar to Emacs Lisp or relate
specifically to editing.
- This is edition 2.5.
+ This is edition @value{VERSION} of the GNU Emacs Lisp Reference
+Manual, corresponding to Emacs version @value{EMACSVER}.
@menu
* Caveats:: Flaws and a request for help.
@node Caveats
@section Caveats
+@cindex bugs in this manual
This manual has gone through numerous drafts. It is nearly complete
but not flawless. There are a few topics that are not covered, either
you are criticizing.
@end ifnottex
+@cindex bugs
+@cindex suggestions
Please mail comments and corrections to
@example
@pindex cl
A certain amount of Common Lisp emulation is available via the
-@file{cl} library. @xref{Top,, Common Lisp Extension, cl, Common Lisp
-Extensions}.
+@file{cl} library. @inforef{Top, Overview, cl}.
Emacs Lisp is not at all influenced by Scheme; but the GNU project has
an implementation of Scheme, called Guile. We use Guile in all new GNU
addressed as ``you''. ``The user'' is the person who uses Lisp
programs, including those you write.
-@cindex fonts
+@cindex fonts in this manual
Examples of Lisp code are formatted like this: @code{(list 1 2 3)}.
Names that represent metasyntactic variables, or arguments to a function
being described, are formatted like this: @var{first-number}.
there is no way to determine which representation was actually written
by the programmer.
- In this manual, we use @code{()} when we wish to emphasize that it
-means the empty list, and we use @code{nil} when we wish to emphasize
+ In this manual, we write @code{()} when we wish to emphasize that it
+means the empty list, and we write @code{nil} when we wish to emphasize
that it means the truth value @var{false}. That is a good convention to use
in Lisp programs also.
@example
(cons 'foo ()) ; @r{Emphasize the empty list}
-(not nil) ; @r{Emphasize the truth value @var{false}}
+(setq foo-flag nil) ; @r{Emphasize the truth value @var{false}}
@end example
-@cindex @code{t} and truth
+@cindex @code{t}, uses of
@cindex true
In contexts where a truth value is expected, any non-@code{nil} value
is considered to be @var{true}. However, @code{t} is the preferred way
In Emacs Lisp, @code{nil} and @code{t} are special symbols that always
evaluate to themselves. This is so that you do not need to quote them
to use them as constants in a program. An attempt to change their
-values results in a @code{setting-constant} error. The same is true of
-any symbol whose name starts with a colon (@samp{:}). @xref{Constant
+values results in a @code{setting-constant} error. @xref{Constant
Variables}.
+@defun booleanp object
+Return non-nil iff @var{object} is one of the two canonical boolean
+values: @code{t} or @code{nil}.
+@end defun
+
@node Evaluation Notation
@subsection Evaluation Notation
@cindex evaluation notation
@cindex documentation notation
+@cindex notation
A Lisp expression that you can evaluate is called a @dfn{form}.
Evaluating a form always produces a result, which is a Lisp object. In
displayed in the echo area.
Examples in this manual indicate printed text with @samp{@print{}},
-irrespective of where that text goes. The value returned by evaluating
-the form (here @code{bar}) follows on a separate line.
+irrespective of where that text goes. The value returned by
+evaluating the form (here @code{bar}) follows on a separate line with
+@samp{@result{}}.
@example
@group
-(progn (print 'foo) (print 'bar))
+(progn (prin1 'foo) (princ "\n") (prin1 'bar))
@print{} foo
@print{} bar
@result{} bar
function, @code{foo}.
* A Sample Variable Description:: A description of an imaginary
variable,
- @code{electric-future-map}.
+ @code{electric-future-map}.
@end menu
@node A Sample Function Description
arguments default to @code{nil}). Do not write @code{&optional} when
you call the function.
- The keyword @code{&rest} (which must be followed by a single argument
-name) indicates that any number of arguments can follow. The single
-following argument name will have a value, as a variable, which is a
-list of all these remaining arguments. Do not write @code{&rest} when
-you call the function.
+ The keyword @code{&rest} (which must be followed by a single
+argument name) indicates that any number of arguments can follow. The
+single argument name following @code{&rest} will receive, as its
+value, a list of all the remaining arguments passed to the function.
+Do not write @code{&rest} when you call the function.
Here is a description of an imaginary function @code{foo}:
@cindex variable descriptions
@cindex option descriptions
- A @dfn{variable} is a name that can hold a value. Although any
-variable can be set by the user, certain variables that exist
-specifically so that users can change them are called @dfn{user
+ A @dfn{variable} is a name that can hold a value. Although nearly
+all variables can be set by the user, certain variables exist
+specifically so that users can change them; these are called @dfn{user
options}. Ordinary variables and user options are described using a
format like that for functions except that there are no arguments.
These facilities provide information about which version of Emacs is
in use.
-@deffn Command emacs-version
+@deffn Command emacs-version &optional here
This function returns a string describing the version of Emacs that is
running. It is useful to include this string in bug reports.
@end group
@end smallexample
-Called interactively, the function prints the same information in the
-echo area.
+If @var{here} is non-@code{nil}, it inserts the text in the buffer
+before point, and returns @code{nil}. Called interactively, the
+function prints the same information in the echo area, but giving a
+prefix argument makes @var{here} non-@code{nil}.
@end deffn
@defvar emacs-build-time
The value of this variable is the version of Emacs being run. It is a
string such as @code{"20.3.1"}. The last number in this string is not
really part of the Emacs release version number; it is incremented each
-time you build Emacs in any given directory. A value with three numeric
+time you build Emacs in any given directory. A value with four numeric
components, such as @code{"20.3.9.1"}, indicates an unreleased test
version.
@end defvar
Rockwell, Per Starb@"ack, Shinichirou Sugou, Kimmo Suominen, Edward Tharp,
Bill Trost, Rickard Westman, Jean White, Matthew Wilding, Carl Witty,
Dale Worley, Rusty Wright, and David D. Zuhn.
+
+@ignore
+ arch-tag: d156593f-82f8-4708-a844-204e48f7f2aa
+@end ignore