This is Info file ../../info/xemacs.info, produced by Makeinfo-1.63
from the input file xemacs.texi.

   This file documents the XEmacs editor.

   Copyright (C) 1985, 1986, 1988 Richard M. Stallman.  Copyright (C)
1991, 1992, 1993, 1994 Lucid, Inc.  Copyright (C) 1993, 1994 Sun
Microsystems, Inc.  Copyright (C) 1995 Amdahl Corporation.

   Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.

   Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided also
that the sections entitled "The GNU Manifesto", "Distribution" and "GNU
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under the
terms of a permission notice identical to this one.

   Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the author instead of in the original English.


File: xemacs.info,  Node: Comments,  Next: Balanced Editing,  Prev: Matching,  Up: Programs

Manipulating Comments
=====================

   The comment commands insert, kill and align comments.

`M-;'
     Insert or align comment (`indent-for-comment').

`C-x ;'
     Set comment column (`set-comment-column').

`C-u - C-x ;'
     Kill comment on current line (`kill-comment').

`M-LFD'
     Like RET followed by inserting and aligning a comment
     (`indent-new-comment-line').

   The command that creates a comment is `Meta-;'
(`indent-for-comment').  If there is no comment already on the line, a
new comment is created and aligned at a specific column called the
"comment column".  Emacs creates the comment by inserting the string at
the value of `comment-start'; see below.  Point is left after that
string.  If the text of the line extends past the comment column,
indentation is done to a suitable boundary (usually, at least one space
is inserted).  If the major mode has specified a string to terminate
comments, that string is inserted after point, to keep the syntax valid.

   You can also use `Meta-;' to align an existing comment.  If a line
already contains the string that starts comments, `M-;' just moves
point after it and re-indents it to the conventional place.  Exception:
comments starting in column 0 are not moved.

   Some major modes have special rules for indenting certain kinds of
comments in certain contexts.  For example, in Lisp code, comments which
start with two semicolons are indented as if they were lines of code,
instead of at the comment column.  Comments which start with three
semicolons are supposed to start at the left margin.  Emacs understands
these conventions by indenting a double-semicolon comment using TAB and
by not changing the indentation of a triple-semicolon comment at all.

     ;; This function is just an example.
     ;;; Here either two or three semicolons are appropriate.
     (defun foo (x)
     ;;; And now, the first part of the function:
       ;; The following line adds one.
       (1+ x))           ; This line adds one.

   In C code, a comment preceded on its line by nothing but whitespace
is indented like a line of code.

   Even when an existing comment is properly aligned, `M-;' is still
useful for moving directly to the start of the comment.

   `C-u - C-x ;' (`kill-comment') kills the comment on the current
line, if there is one.  The indentation before the start of the comment
is killed as well.  If there does not appear to be a comment in the
line, nothing happens.  To reinsert the comment on another line, move
to the end of that line, type first `C-y', and then `M-;' to realign
the comment.  Note that `C-u - C-x ;' is not a distinct key; it is `C-x
;' (`set-comment-column') with a negative argument.  That command is
programmed to call `kill-comment' when called with a negative argument.
However, `kill-comment' is a valid command which you could bind
directly to a key if you wanted to.

Multiple Lines of Comments
--------------------------

   If you are typing a comment and want to continue it on another line,
use the command `Meta-LFD' (`indent-new-comment-line'), which
terminates the comment you are typing, creates a new blank line
afterward, and begins a new comment indented under the old one.  If
Auto Fill mode is on and you go past the fill column while typing, the
comment is continued in just this fashion.  If point is not at the end
of the line when you type `M-LFD', the text on the rest of the line
becomes part of the new comment line.

Options Controlling Comments
----------------------------

   The comment column is stored in the variable `comment-column'.  You
can explicitly set it to a number.  Alternatively, the command `C-x ;'
(`set-comment-column') sets the comment column to the column point is
at.  `C-u C-x ;' sets the comment column to match the last comment
before point in the buffer, and then calls `Meta-;' to align the
current line's comment under the previous one.  Note that `C-u - C-x ;'
runs the function `kill-comment' as described above.

   `comment-column' is a per-buffer variable; altering the variable
affects only the current buffer.  You can also change the default value.
*Note Locals::.  Many major modes initialize this variable for the
current buffer.

   The comment commands recognize comments based on the regular
expression that is the value of the variable `comment-start-skip'.
This regexp should not match the null string.  It may match more than
the comment starting delimiter in the strictest sense of the word; for
example, in C mode the value of the variable is `"/\\*+ *"', which
matches extra stars and spaces after the `/*' itself.  (Note that `\\'
is needed in Lisp syntax to include a `\' in the string, which is needed
to deny the first star its special meaning in regexp syntax.  *Note
Regexps::.)

   When a comment command makes a new comment, it inserts the value of
`comment-start' to begin it.  The value of `comment-end' is inserted
after point and will follow the text you will insert into the comment.
In C mode, `comment-start' has the value `"/* "' and `comment-end' has
the value `" */"'.

   `comment-multi-line' controls how `M-LFD'
(`indent-new-comment-line') behaves when used inside a comment.  If
`comment-multi-line' is `nil', as it normally is, then `M-LFD'
terminates the comment on the starting line and starts a new comment on
the new following line.  If `comment-multi-line' is not `nil', then
`M-LFD' sets up the new following line as part of the same comment that
was found on the starting line.  This is done by not inserting a
terminator on the old line and not inserting a starter on the new line.
In languages where multi-line comments are legal, the value you choose
for this variable is a matter of taste.

   The variable `comment-indent-hook' should contain a function that is
called to compute the indentation for a newly inserted comment or for
aligning an existing comment.  Major modes set this variable
differently.  The function is called with no arguments, but with point
at the beginning of the comment, or at the end of a line if a new
comment is to be inserted.  The function should return the column in
which the comment ought to start.  For example, in Lisp mode, the
indent hook function bases its decision on the number of semicolons
that begin an existing comment and on the code in the preceding lines.


File: xemacs.info,  Node: Balanced Editing,  Next: Lisp Completion,  Prev: Comments,  Up: Programs

Editing Without Unbalanced Parentheses
======================================

`M-('
     Put parentheses around next sexp(s) (`insert-parentheses').

`M-)'
     Move past next close parenthesis and re-indent
     (`move-over-close-and-reindent').

   The commands `M-(' (`insert-parentheses') and `M-)'
(`move-over-close-
and-reindent') are designed to facilitate a style of editing which
keeps parentheses balanced at all times.  `M-(' inserts a pair of
parentheses, either together as in `()', or, if given an argument,
around the next several sexps, and leaves point after the open
parenthesis.  Instead of typing `( F O O )', you can type `M-( F O O',
which has the same effect except for leaving the cursor before the
close parenthesis.  You can then type `M-)', which moves past the close
parenthesis, deletes any indentation preceding it (in this example
there is none), and indents with LFD after it.


File: xemacs.info,  Node: Lisp Completion,  Next: Documentation,  Prev: Balanced Editing,  Up: Programs

Completion for Lisp Symbols
===========================

   Completion usually happens in the minibuffer.  An exception is
completion for Lisp symbol names, which is available in all buffers.

   The command `M-TAB' (`lisp-complete-symbol') takes the partial Lisp
symbol before point to be an abbreviation, and compares it against all
non-trivial Lisp symbols currently known to Emacs.  Any additional
characters that they all have in common are inserted at point.
Non-trivial symbols are those that have function definitions, values, or
properties.

   If there is an open-parenthesis immediately before the beginning of
the partial symbol, only symbols with function definitions are
considered as completions.

   If the partial name in the buffer has more than one possible
completion and they have no additional characters in common, a list of
all possible completions is displayed in another window.


File: xemacs.info,  Node: Documentation,  Next: Change Log,  Prev: Lisp Completion,  Up: Programs

Documentation Commands
======================

   As you edit Lisp code to be run in Emacs, you can use the commands
`C-h f' (`describe-function') and `C-h v' (`describe-variable') to
print documentation of functions and variables you want to call.  These
commands use the minibuffer to read the name of a function or variable
to document, and display the documentation in a window.

   For extra convenience, these commands provide default arguments
based on the code in the neighborhood of point.  `C-h f' sets the
default to the function called in the innermost list containing point.
`C-h v' uses the symbol name around or adjacent to point as its default.

   The `M-x manual-entry' command gives you access to documentation on
Unix commands, system calls, and libraries.  The command reads a topic
as an argument, and displays the Unix manual page for that topic.
`manual-entry' always searches all 8 sections of the manual and
concatenates all the entries it finds.  For example, the topic
`termcap' finds the description of the termcap library from section 3,
followed by the description of the termcap data base from section 5.


File: xemacs.info,  Node: Change Log,  Next: Tags,  Prev: Documentation,  Up: Programs

Change Logs
===========

   The Emacs command `M-x add-change-log-entry' helps you keep a record
of when and why you have changed a program.  It assumes that you have a
file in which you write a chronological sequence of entries describing
individual changes.  The default is to store the change entries in a
file called `ChangeLog' in the same directory as the file you are
editing.  The same `ChangeLog' file therefore records changes for all
the files in a directory.

   A change log entry starts with a header line that contains your name
and the current date.  Except for these header lines, every line in the
change log starts with a tab.  One entry can describe several changes;
each change starts with a line starting with a tab and a star.  `M-x
add-change-log-entry' visits the change log file and creates a new entry
unless the most recent entry is for today's date and your name.  In
either case, it adds a new line to start the description of another
change just after the header line of the entry.  When `M-x
add-change-log-entry' is finished, all is prepared for you to edit in
the description of what you changed and how.  You must then save the
change log file yourself.

   The change log file is always visited in Indented Text mode, which
means that LFD and auto-filling indent each new line like the previous
line.  This is convenient for entering the contents of an entry, which
must be indented.  *Note Text Mode::.

   Here is an example of the formatting conventions used in the change
log for Emacs:

     Wed Jun 26 19:29:32 1985  Richard M. Stallman  (rms at mit-prep)
     
             * xdisp.c (try_window_id):
             If C-k is done at end of next-to-last line,
             this fn updates window_end_vpos and cannot leave
             window_end_pos nonnegative (it is zero, in fact).
             If display is preempted before lines are output,
             this is inconsistent.  Fix by setting
             blank_end_of_window to nonzero.
     
     Tue Jun 25 05:25:33 1985  Richard M. Stallman  (rms at mit-prep)
     
             * cmds.c (Fnewline):
             Call the auto fill hook if appropriate.
     
             * xdisp.c (try_window_id):
             If point is found by compute_motion after xp, record that
             permanently.  If display_text_line sets point position wrong
             (case where line is killed, point is at eob and that line is
             not displayed), set it again in final compute_motion.


File: xemacs.info,  Node: Tags,  Next: Fortran,  Prev: Change Log,  Up: Programs

Tag Tables
==========

   A "tag table" is a description of how a multi-file program is broken
up into files.  It lists the names of the component files and the names
and positions of the functions in each file.  Grouping the related
files makes it possible to search or replace through all the files with
one command.  Recording the function names and positions makes it
possible to use the `Meta-.' command, which finds the definition of a
function without asking for information on the file it is in.

   Tag tables are stored in files called "tag table files".  The
conventional name for a tag table file is `TAGS'.

   Each entry in the tag table records the name of one tag, the name of
the file that the tag is defined in (implicitly), and the position in
that file of the tag's definition.

   The programming language of a file determines what names are recorded
in the tag table depends on.  Normally, Emacs includes all functions and
subroutines, and may also include global variables, data types, and
anything else convenient.  Each recorded name is called a "tag".

* Menu:

* Tag Syntax::
* Create Tag Table::
* Select Tag Table::
* Find Tag::
* Tags Search::
* Tags Stepping::
* List Tags::


File: xemacs.info,  Node: Tag Syntax,  Next: Create Tag Table,  Prev: Tags,  Up: Tags

Source File Tag Syntax
----------------------

   In Lisp code, any function defined with `defun', any variable
defined with `defvar' or `defconst', and the first argument of any
expression that starts with `(def' in column zero, is a tag.

   In C code, any C function is a tag, and so is any typedef if `-t' is
specified when the tag table is constructed.

   In Fortran code, functions and subroutines are tags.

   In LaTeX text, the argument of any of the commands `\chapter',
`\section', `\subsection', `\subsubsection', `\eqno', `\label', `\ref',
`\cite', `\bibitem', and
`\typeout' is a tag.


File: xemacs.info,  Node: Create Tag Table,  Next: Select Tag Table,  Prev: Tag Syntax,  Up: Tags

Creating Tag Tables
-------------------

   The `etags' program is used to create a tag table file.  It knows
the syntax of C, Fortran, LaTeX, Scheme, and Emacs Lisp/Common Lisp.  To
use `etags', use it as a shell command:

     etags INPUTFILES...

The program reads the specified files and writes a tag table named
`TAGS' in the current working directory.  `etags' recognizes the
language used in an input file based on the name and contents of the
file; there are no switches for specifying the language.  The `-t'
switch tells `etags' to record typedefs in C code as tags.

   If the tag table data become outdated due to changes in the files
described in the table, you can update the tag table by running the
program from the shell again.  It is not necessary to do this often.

   If the tag table fails to record a tag, or records it for the wrong
file, Emacs cannot find its definition.  However, if the position
recorded in the tag table becomes a little bit wrong (due to some
editing in the file that the tag definition is in), the only
consequence is to slow down finding the tag slightly.  Even if the
stored position is very wrong, Emacs will still find the tag, but it
must search the entire file for it.

   You should update a tag table when you define new tags you want to
have listed, when you move tag definitions from one file to another, or
when changes become substantial.  You don't have to update the tag
table after each edit, or even every day.


File: xemacs.info,  Node: Select Tag Table,  Next: Find Tag,  Prev: Create Tag Table,  Up: Tags

Selecting a Tag Table
---------------------

   At any time Emacs has one "selected" tag table, and all the commands
for working with tag tables use the selected one.  To select a tag
table, use the variable `tag-table-alist'.

   The value of `tag-table-alist' is a list that determines which
`TAGS' files should be active for a given buffer.  This is not really
an association list, in that all elements are checked.  The car of each
element of this list is a pattern against which the buffers file name
is compared; if it matches, then the cdr of the list should be the name
of the tags table to use.  If more than one element of this list
matches the buffers file name, all of the associated tags tables are
used.  Earlier ones are searched first.

   If the car of elements of this list are strings, they are treated as
regular-expressions against which the file is compared (like the
`auto-mode-alist').  If they are not strings, they are evaluated.  If
they evaluate to non-`nil', the current buffer is considered to match.

   If the cdr of the elements of this list are strings, they are
assumed to name a tags file.  If they name a directory, the string
`tags' is appended to them to get the file name.  If they are not
strings, they are evaluated and must return an appropriate string.

   For example:

       (setq tag-table-alist
     	'(("/usr/src/public/perl/" . "/usr/src/public/perl/perl-3.0/")
     	  ("\\.el$" . "/usr/local/emacs/src/")
     	  ("/jbw/gnu/" . "/usr15/degree/stud/jbw/gnu/")
     	  ("" . "/usr/local/emacs/src/")
     	  ))

   The example defines the tag table alist in the following way:

   * Anything in the directory `/usr/src/public/perl/' should use the
     `TAGS' file `/usr/src/public/perl/perl-3.0/TAGS'.

   * Files ending in `.el' should use the `TAGS' file
     `/usr/local/emacs/src/TAGS'.

   * Anything in or below the directory `/jbw/gnu/' should use the
     `TAGS' file `/usr15/degree/stud/jbw/gnu/TAGS'.

   If you had a file called `/usr/jbw/foo.el', it would use both `TAGS'
files,
`/usr/local/emacs/src/TAGS' and `/usr15/degree/stud/jbw/gnu/TAGS' (in
that order), because it matches both patterns.

   If the buffer-local variable `buffer-tag-table' is set, it names a
tags table that is searched before all others when `find-tag' is
executed from this buffer.

   If there is a file called `TAGS' in the same directory as the file
in question, then that tags file will always be used as well (after the
`buffer-tag-table' but before the tables specified by this list).

   If the variable `tags-file-name' is set, the `TAGS' file it names
will apply to all buffers (for backwards compatibility.)  It is searched
first.

   If the value of the variable `tags-always-build-completion-table' is
`t', the tags file will always be added to the completion table without
asking first, regardless of the size of the tags file.

   The function `M-x visit-tags-table', is largely made obsolete by the
variable `tag-table-alist', tells tags commands to use the tags table
file FILE first.  The FILE should be the name of a file created with
the `etags' program.  A directory name is also acceptable; it means the
file `TAGS' in that directory.  The function only stores the file name
you provide in the variable `tags-file-name'.  Emacs does not actually
read in the tag table contents until you try to use them.  You can set
the variable explicitly instead of using `visit-tags-table'.  The value
of the variable `tags-file-name' is the name of the tags table used by
all buffers.  This is for backward compatibility, and is largely
supplanted by the variable `tag-table-alist'.


File: xemacs.info,  Node: Find Tag,  Next: Tags Search,  Prev: Select Tag Table,  Up: Tags

Finding a Tag
-------------

   The most important thing that a tag table enables you to do is to
find the definition of a specific tag.

`M-. TAG &OPTIONAL OTHER-WINDOW'
     Find first definition of TAG (`find-tag').

`C-u M-.'
     Find next alternate definition of last tag specified.

`C-x 4 . TAG'
     Find first definition of TAG, but display it in another window
     (`find-tag-other-window').

   `M-.' (`find-tag') is the command to find the definition of a
specified tag.  It searches through the tag table for that tag, as a
string, then uses the tag table information to determine the file in
which the definition is used and the approximate character position of
the definition in the file.  Then `find-tag' visits the file, moves
point to the approximate character position, and starts searching
ever-increasing distances away for the text that should appear at the
beginning of the definition.

   If an empty argument is given (by typing RET), the sexp in the
buffer before or around point is used as the name of the tag to find.
*Note Lists::, for information on sexps.

   The argument to `find-tag' need not be the whole tag name; it can be
a substring of a tag name.  However, there can be many tag names
containing the substring you specify.  Since `find-tag' works by
searching the text of the tag table, it finds the first tag in the table
that the specified substring appears in.  To find other tags that match
the substring, give `find-tag' a numeric argument, as in `C-u M-.'.
This does not read a tag name, but continues searching the tag table's
text for another tag containing the same substring last used.  If your
keyboard has a real META key, `M-0 M-.' is an easier alternative to
`C-u M-.'.

   If the optional second argument OTHER-WINDOW is non-`nil', it uses
another window to display the tag.  Multiple active tags tables and
completion are supported.

   Variables of note include the following:

`tag-table-alist'
     Controls which tables apply to which buffers.

`tags-file-name'
     Stores a default tags table.

`tags-build-completion-table'
     Controls completion behavior.

`buffer-tag-table'
     Specifies a buffer-local table.

`make-tags-files-invisible'
     Sets whether tags tables should be very hidden.

`tag-mark-stack-max'
     Specifies how many tags-based hops to remember.

   Like most commands that can switch buffers, `find-tag' has another
similar command that displays the new buffer in another window.  `C-x 4
.' invokes the function `find-tag-other-window'.  (This key sequence
ends with a period.)

   Emacs comes with a tag table file `TAGS' (in the directory
containing Lisp libraries) that includes all the Lisp libraries and all
the C sources of Emacs.  By specifying this file with `visit-tags-table'
and then using `M-.' you can quickly look at the source of any Emacs
function.


File: xemacs.info,  Node: Tags Search,  Next: Tags Stepping,  Prev: Find Tag,  Up: Tags

Searching and Replacing with Tag Tables
---------------------------------------

   The commands in this section visit and search all the files listed
in the selected tag table, one by one.  For these commands, the tag
table serves only to specify a sequence of files to search.  A related
command is `M-x grep' (*note Compilation::.).

`M-x tags-search'
     Search for the specified regexp through the files in the selected
     tag table.

`M-x tags-query-replace'
     Perform a `query-replace' on each file in the selected tag table.

`M-,'
     Restart one of the commands above, from the current location of
     point (`tags-loop-continue').

   `M-x tags-search' reads a regexp using the minibuffer, then visits
the files of the selected tag table one by one, and searches through
each file for that regexp.  It displays the name of the file being
searched so you can follow its progress.  As soon as an occurrence is
found, `tags-search' returns.

   After you have found one match, you probably want to find all the
rest.  To find one more match, type `M-,' (`tags-loop-continue') to
resume the `tags-search'.  This searches the rest of the current
buffer, followed by the remaining files of the tag table.

   `M-x tags-query-replace' performs a single `query-replace' through
all the files in the tag table.  It reads a string to search for and a
string to replace with, just like ordinary `M-x query-replace'.  It
searches much like `M-x tags-search' but repeatedly, processing matches
according to your input.  *Note Replace::, for more information on
`query-replace'.

   It is possible to get through all the files in the tag table with a
single invocation of `M-x tags-query-replace'.  But since any
unrecognized character causes the command to exit, you may need to
continue from where you left off.  You can use `M-,' to do this.  It
resumes the last tags search or replace command that you did.

   It may have struck you that `tags-search' is a lot like `grep'.  You
can also run `grep' itself as an inferior of Emacs and have Emacs show
you the matching lines one by one.  This works mostly the same as
running a compilation and having Emacs show you where the errors were.
*Note Compilation::.


File: xemacs.info,  Node: Tags Stepping,  Next: List Tags,  Prev: Tags Search,  Up: Tags

Stepping Through a Tag Table
----------------------------

   If you wish to process all the files in a selected tag table, but
`M-x tags-search' and `M-x tags-query-replace' are not giving you the
desired result, you can use `M-x next-file'.

`C-u M-x next-file'
     With a numeric argument, regardless of its value, visit the first
     file in the tag table and prepare to advance sequentially by files.

`M-x next-file'
     Visit the next file in the selected tag table.


File: xemacs.info,  Node: List Tags,  Prev: Tags Stepping,  Up: Tags

Tag Table Inquiries
-------------------

`M-x list-tags'
     Display a list of the tags defined in a specific program file.

`M-x tags-apropos'
     Display a list of all tags matching a specified regexp.

   `M-x list-tags' reads the name of one of the files described by the
selected tag table, and displays a list of all the tags defined in that
file.  The "file name" argument is really just a string to compare
against the names recorded in the tag table; it is read as a string
rather than a file name.  Therefore, completion and defaulting are not
available, and you must enter the string the same way it appears in the
tag table.  Do not include a directory as part of the file name unless
the file name recorded in the tag table contains that directory.

   `M-x tags-apropos' is like `apropos' for tags.  It reads a regexp,
then finds all the tags in the selected tag table whose entries match
that regexp, and displays the tag names found.


File: xemacs.info,  Node: Fortran,  Next: Asm Mode,  Prev: Tags,  Up: Programs

Fortran Mode
============

   Fortran mode provides special motion commands for Fortran statements
and subprograms, and indentation commands that understand Fortran
conventions of nesting, line numbers, and continuation statements.

   Special commands for comments are provided because Fortran comments
are unlike those of other languages.

   Built-in abbrevs optionally save typing when you insert Fortran
keywords.

   Use `M-x fortran-mode' to switch to this major mode.  Doing so calls
the value of `fortran-mode-hook' as a function of no arguments if that
variable has a non-`nil' value.

* Menu:

* Motion: Fortran Motion.     Moving point by statements or subprograms.
* Indent: Fortran Indent.     Indentation commands for Fortran.
* Comments: Fortran Comments. Inserting and aligning comments.
* Columns: Fortran Columns.   Measuring columns for valid Fortran.
* Abbrev: Fortran Abbrev.     Built-in abbrevs for Fortran keywords.

   Fortran mode was contributed by Michael Prange.


File: xemacs.info,  Node: Fortran Motion,  Next: Fortran Indent,  Prev: Fortran,  Up: Fortran

Motion Commands
---------------

   Fortran mode provides special commands to move by subprograms
(functions and subroutines) and by statements.  There is also a command
to put the region around one subprogram, which is convenient for
killing it or moving it.

`C-M-a'
     Move to beginning of subprogram
     (`beginning-of-fortran-subprogram').

`C-M-e'
     Move to end of subprogram (`end-of-fortran-subprogram').

`C-M-h'
     Put point at beginning of subprogram and mark at end
     (`mark-fortran-subprogram').

`C-c C-n'
     Move to beginning of current or next statement (`fortran-next-
     statement').

`C-c C-p'
     Move to beginning of current or previous statement (`fortran-
     previous-statement').


File: xemacs.info,  Node: Fortran Indent,  Next: Fortran Comments,  Prev: Fortran Motion,  Up: Fortran

Fortran Indentation
-------------------

   Special commands and features are available for indenting Fortran
code.  They make sure various syntactic entities (line numbers, comment
line indicators, and continuation line flags) appear in the columns
that are required for standard Fortran.

* Menu:

* Commands: ForIndent Commands. Commands for indenting Fortran.
* Numbers:  ForIndent Num.      How line numbers auto-indent.
* Conv:     ForIndent Conv.     Conventions you must obey to avoid trouble.
* Vars:     ForIndent Vars.     Variables controlling Fortran indent style.


File: xemacs.info,  Node: ForIndent Commands,  Next: ForIndent Num,  Prev: Fortran Indent,  Up: Fortran Indent

Fortran Indentation Commands
............................

`TAB'
     Indent the current line (`fortran-indent-line').

`M-LFD'
     Break the current line and set up a continuation line.

`C-M-q'
     Indent all the lines of the subprogram point is in
     (`fortran-indent-subprogram').

   TAB is redefined by Fortran mode to reindent the current line for
Fortran (`fortran-indent-line').  Line numbers and continuation markers
are indented to their required columns, and the body of the statement
is independently indented, based on its nesting in the program.

   The key `C-M-q' is redefined as `fortran-indent-subprogram', a
command that reindents all the lines of the Fortran subprogram
(function or subroutine) containing point.

   The key `M-LFD' is redefined as `fortran-split-line', a command to
split a line in the appropriate fashion for Fortran.  In a non-comment
line, the second half becomes a continuation line and is indented
accordingly.  In a comment line, both halves become separate comment
lines.


File: xemacs.info,  Node: ForIndent Num,  Next: ForIndent Conv,  Prev: ForIndent Commands,  Up: Fortran Indent

Line Numbers and Continuation
.............................

   If a number is the first non-whitespace in the line, it is assumed
to be a line number and is moved to columns 0 through 4.  (Columns are
always counted from 0 in XEmacs.)  If the text on the line starts with
the conventional Fortran continuation marker `$', it is moved to column
5.  If the text begins with any non whitespace character in column 5,
it is assumed to be an unconventional continuation marker and remains
in column 5.

   Line numbers of four digits or less are normally indented one space.
This amount is controlled by the variable `fortran-line-number-indent',
which is the maximum indentation a line number can have.  Line numbers
are indented to right-justify them to end in column 4 unless that would
require more than the maximum indentation.  The default value of the
variable is 1.

   Simply inserting a line number is enough to indent it according to
these rules.  As each digit is inserted, the indentation is recomputed.
To turn off this feature, set the variable
`fortran-electric-line-number' to `nil'.  Then inserting line numbers
is like inserting anything else.


File: xemacs.info,  Node: ForIndent Conv,  Next: ForIndent Vars,  Prev: ForIndent Num,  Up: Fortran Indent

Syntactic Conventions
.....................

   Fortran mode assumes that you follow certain conventions that
simplify the task of understanding a Fortran program well enough to
indent it properly:

   * Two nested `do' loops never share a `continue' statement.

   * The same character appears in column 5 of all continuation lines.
     It is the value of the variable `fortran-continuation-char'.  By
     default, this character is `$'.

If you fail to follow these conventions, the indentation commands may
indent some lines unaesthetically.  However, a correct Fortran program
will retain its meaning when reindented even if the conventions are not
followed.


File: xemacs.info,  Node: ForIndent Vars,  Prev: ForIndent Conv,  Up: Fortran Indent

Variables for Fortran Indentation
.................................

   Several additional variables control how Fortran indentation works.

`fortran-do-indent'
     Extra indentation within each level of `do' statement (the default
     is 3).

`fortran-if-indent'
     Extra indentation within each level of `if' statement (the default
     is 3).

`fortran-continuation-indent'
     Extra indentation for bodies of continuation lines (the default is
     5).

`fortran-check-all-num-for-matching-do'
     If this is `nil', indentation assumes that each `do' statement
     ends on a `continue' statement.  Therefore, when computing
     indentation for a statement other than `continue', it can save
     time by not checking for a `do' statement ending there.  If this
     is non-`nil', indenting any numbered statement must check for a
     `do' that ends there.  The default is `nil'.

`fortran-minimum-statement-indent'
     Minimum indentation for Fortran statements.  For standard Fortran,
     this is 6.  Statement bodies are always indented at least this
     much.


File: xemacs.info,  Node: Fortran Comments,  Next: Fortran Columns,  Prev: Fortran Indent,  Up: Fortran

Comments
--------

   The usual Emacs comment commands assume that a comment can follow a
line of code.  In Fortran, the standard comment syntax requires an
entire line to be just a comment.  Therefore, Fortran mode replaces the
standard Emacs comment commands and defines some new variables.

   Fortran mode can also handle a non-standard comment syntax where
comments start with `!' and can follow other text.  Because only some
Fortran compilers accept this syntax, Fortran mode will not insert such
comments unless you have specified to do so in advance by setting the
variable `comment-start' to `"!"' (*note Variables::.).

`M-;'
     Align comment or insert new comment (`fortran-comment-indent').

`C-x ;'
     Applies to nonstandard `!' comments only.

`C-c ;'
     Turn all lines of the region into comments, or (with arg) turn
     them back into real code (`fortran-comment-region').

   `M-;' in Fortran mode is redefined as the command
`fortran-comment-indent'.  Like the usual `M-;' command, it recognizes
an existing comment and aligns its text appropriately.  If there is no
existing comment, a comment is inserted and aligned.

   Inserting and aligning comments is not the same in Fortran mode as in
other modes.  When a new comment must be inserted, a full-line comment
is inserted if the current line is blank.  On a non-blank line, a
non-standard `!' comment is inserted if you previously specified you
wanted to use them.  Otherwise a full-line comment is inserted on a new
line before the current line.

   Non-standard `!' comments are aligned like comments in other
languages, but full-line comments are aligned differently.  In a
standard full-line comment, the comment delimiter itself must always
appear in column zero.  What can be aligned is the text within the
comment.  You can choose from three styles of alignment by setting the
variable `fortran-comment-indent-style' to one of these values:

`fixed'
     The text is aligned at a fixed column, which is the value of
     `fortran-comment-line-column'.  This is the default.

`relative'
     The text is aligned as if it were a line of code, but with an
     additional `fortran-comment-line-column' columns of indentation.

`nil'
     Text in full-line columns is not moved automatically.

   You can also specify the character to be used to indent within
full-line comments by setting the variable `fortran-comment-indent-char'
to the character you want to use.

   Fortran mode introduces two variables `comment-line-start' and
`comment-line-start-skip', which do for full-line comments what
`comment-start' and `comment-start-skip' do for ordinary text-following
comments.  Normally these are set properly by Fortran mode, so you do
not need to change them.

   The normal Emacs comment command `C-x ;' has not been redefined.  It
can therefore be used if you use `!' comments, but is useless in
Fortran mode otherwise.

   The command `C-c ;' (`fortran-comment-region') turns all the lines
of the region into comments by inserting the string `C$$$' at the front
of each one.  With a numeric arg, the region is turned back into live
code by deleting `C$$$' from the front of each line.  You can control
the string used for the comments by setting the variable
`fortran-comment-region'.  Note that here we have an example of a
command and a variable with the same name; the two uses of the name
never conflict because in Lisp and in Emacs it is always clear from the
context which one is referred to.


File: xemacs.info,  Node: Fortran Columns,  Next: Fortran Abbrev,  Prev: Fortran Comments,  Up: Fortran

Columns
-------

`C-c C-r'
     Displays a "column ruler" momentarily above the current line
     (`fortran-column-ruler').

`C-c C-w'
     Splits the current window horizontally so that it is 72 columns
     wide.  This may help you avoid going over that limit
     (`fortran-window-create').

   The command `C-c C-r' (`fortran-column-ruler') shows a column ruler
above the current line.  The comment ruler consists of two lines of
text that show you the locations of columns with special significance
in Fortran programs.  Square brackets show the limits of the columns for
line numbers, and curly brackets show the limits of the columns for the
statement body.  Column numbers appear above them.

   Note that the column numbers count from zero, as always in XEmacs.
As a result, the numbers may not be those you are familiar with; but the
actual positions in the line are standard Fortran.

   The text used to display the column ruler is the value of the
variable `fortran-comment-ruler'.  By changing this variable, you can
change the display.

   For even more help, use `C-c C-w' (`fortran-window-create'), a
command which splits the current window horizontally, resulting in a
window 72 columns wide.  When you edit in this window, you can
immediately see when a line gets too wide to be correct Fortran.


File: xemacs.info,  Node: Fortran Abbrev,  Prev: Fortran Columns,  Up: Fortran

Fortran Keyword Abbrevs
-----------------------

   Fortran mode provides many built-in abbrevs for common keywords and
declarations.  These are the same sort of abbrevs that you can define
yourself.  To use them, you must turn on Abbrev mode.  *note Abbrevs::..

   The built-in abbrevs are unusual in one way: they all start with a
semicolon.  You cannot normally use semicolon in an abbrev, but Fortran
mode makes this possible by changing the syntax of semicolon to "word
constituent".

   For example, one built-in Fortran abbrev is `;c' for `continue'.  If
you insert `;c' and then insert a punctuation character such as a space
or a newline, the `;c' changes automatically to `continue', provided
Abbrev mode is enabled.

   Type `;?' or `;C-h' to display a list of all built-in Fortran
abbrevs and what they stand for.


File: xemacs.info,  Node: Asm Mode,  Prev: Fortran,  Up: Programs

Asm Mode
========

   Asm mode is a major mode for editing files of assembler code.  It
defines these commands:

`TAB'
     `tab-to-tab-stop'.

`LFD'
     Insert a newline and then indent using `tab-to-tab-stop'.

`:'
     Insert a colon and then remove the indentation from before the
     label preceding colon.  Then do `tab-to-tab-stop'.

`;'
     Insert or align a comment.

   The variable `asm-comment-char' specifies which character starts
comments in assembler syntax.


File: xemacs.info,  Node: Running,  Next: Abbrevs,  Prev: Programs,  Up: Top

Compiling and Testing Programs
******************************

   The previous chapter discusses the Emacs commands that are useful for
making changes in programs.  This chapter deals with commands that
assist in the larger process of developing and maintaining programs.

* Menu:

* Compilation::        Compiling programs in languages other than Lisp
                        (C, Pascal, etc.)
* Modes: Lisp Modes.   Various modes for editing Lisp programs, with
                       different facilities for running the Lisp programs.
* Libraries: Lisp Libraries.      Creating Lisp programs to run in Emacs.
* Eval: Lisp Eval.     Executing a single Lisp expression in Emacs.
* Debug: Lisp Debug.   Debugging Lisp programs running in Emacs.
* Interaction: Lisp Interaction.  Executing Lisp in an Emacs buffer.
* External Lisp::      Communicating through Emacs with a separate Lisp.


File: xemacs.info,  Node: Compilation,  Next: Lisp Modes,  Prev: Running,  Up: Running

Running "make", or Compilers Generally
======================================

   Emacs can run compilers for non-interactive languages like C and
Fortran as inferior processes, feeding the error log into an Emacs
buffer.  It can also parse the error messages and visit the files in
which errors are found, moving point to the line where the error
occurred.

`M-x compile'
     Run a compiler asynchronously under Emacs, with error messages to
     `*compilation*' buffer.

`M-x grep'
     Run `grep' asynchronously under Emacs, with matching lines listed
     in the buffer named `*compilation*'.

`M-x kill-compilation'
     Kill the process made by the `M-x compile' command.

`M-x kill-grep'
     Kill the running compilation or `grep' subprocess.

`C-x `'
     Visit the next compiler error message or `grep' match.

   To run `make' or another compiler, type `M-x compile'.  This command
reads a shell command line using the minibuffer, then executes the
specified command line in an inferior shell with output going to the
buffer named `*compilation*'.  By default, the current buffer's default
directory is used as the working directory for the execution of the
command; therefore, the makefile comes from this directory.

   When the shell command line is read, the minibuffer appears
containing a default command line (the command you used the last time
you typed `M-x compile').  If you type just RET, the same command line
is used again.  The first `M-x compile' provides `make -k' as the
default.  The default is taken from the variable `compile-command'; if
the appropriate compilation command for a file is something other than
`make -k', it can be useful to have the file specify a local value for
`compile-command' (*note File Variables::.).

   When you start a compilation, the buffer `*compilation*' is
displayed in another window but not selected.  Its mode line displays
the word `run' or `exit' in the parentheses to tell you whether
compilation is finished.  You do not have to keep this buffer visible;
compilation continues in any case.

   To kill the compilation process, type `M-x-kill-compilation'.  The
mode line of the `*compilation*' buffer changes to say `signal' instead
of `run'.  Starting a new compilation also kills any running
compilation, as only one can occur at any time.  Starting a new
compilation prompts for confirmation before actually killing a
compilation that is running.

   To parse the compiler error messages, type `C-x `' (`next-error').
The character following `C-x' is the grave accent, not the single
quote.  The command displays the buffer `*compilation*' in one window
and the buffer in which the next error occurred in another window.
Point in that buffer is moved to the line where the error was found.
The corresponding error message is scrolled to the top of the window in
which `*compilation*' is displayed.

   The first time you use `C-x `' after the start of a compilation, it
parses all the error messages, visits all the files that have error
messages, and creates markers pointing at the lines the error messages
refer to.  It then moves to the first error message location.
Subsequent uses of `C-x `' advance down the data set up by the first
use.  When the preparsed error messages are exhausted, the next `C-x `'
checks for any more error messages that have come in; this is useful if
you start editing compiler errors while compilation is still going on.
If no additional error messages have come in, `C-x `' reports an error.

   `C-u C-x `' discards the preparsed error message data and parses the
`*compilation*' buffer again, then displays the first error.  This way,
you can process the same set of errors again.

   Instead of running a compiler, you can run `grep' and see the lines
on which matches were found.  To do this, type `M-x grep' with an
argument line that contains the same arguments you would give to
`grep': a `grep'-style regexp (usually in single quotes to quote the
shell's special characters) followed by filenames, which may use
wildcard characters.  The output from `grep' goes in the
`*compilation*' buffer.  You can use `C-x `' to find the lines that
match as if they were compilation errors.

   Note: a shell is used to run the compile command, but the shell is
not run in interactive mode.  In particular, this means that the shell
starts up with no prompt.  If you find your usual shell prompt making an
unsightly appearance in the `*compilation*' buffer, it means you have
made a mistake in your shell's initialization file (`.cshrc' or `.shrc'
or ...) by setting the prompt unconditionally.  The shell
initialization file should set the prompt only if there already is a
prompt.  Here's how to do it in `csh':

     if ($?prompt) set prompt = ...


File: xemacs.info,  Node: Lisp Modes,  Next: Lisp Libraries,  Prev: Compilation,  Up: Running

Major Modes for Lisp
====================

   Emacs has four different major modes for Lisp.  They are the same in
terms of editing commands, but differ in the commands for executing Lisp
expressions.

Emacs-Lisp mode
     The mode for editing source files of programs to run in Emacs Lisp.
     This mode defines `C-M-x' to evaluate the current defun.  *Note
     Lisp Libraries::.

Lisp Interaction mode
     The mode for an interactive session with Emacs Lisp.  It defines
     LFD to evaluate the sexp before point and insert its value in the
     buffer.  *Note Lisp Interaction::.

Lisp mode
     The mode for editing source files of programs that run in other
     dialects of Lisp than Emacs Lisp.  This mode defines `C-M-x' to
     send the current defun to an inferior Lisp process.  *Note
     External Lisp::.

Inferior Lisp mode
     The mode for an interactive session with an inferior Lisp process.
     This mode combines the special features of Lisp mode and Shell mode
     (*note Shell Mode::.).

Scheme mode
     Like Lisp mode but for Scheme programs.

Inferior Scheme mode
     The mode for an interactive session with an inferior Scheme
     process.


File: xemacs.info,  Node: Lisp Libraries,  Next: Lisp Eval,  Prev: Lisp Modes,  Up: Running

Libraries of Lisp Code for Emacs
================================

   Lisp code for Emacs editing commands is stored in files whose names
conventionally end in `.el'.  This ending tells Emacs to edit them in
Emacs-Lisp mode (*note Lisp Modes::.).

* Menu:

* Loading::		Loading libraries of Lisp code into Emacs for use.
* Compiling Libraries:: Compiling a library makes it load and run faster.
* Mocklisp::		Converting Mocklisp to Lisp so XEmacs can run it.

