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<header>
<copyright>
<year>2003</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
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<title>Erlang mode for Emacs</title>
<prepared>Ingela Anderton</prepared>
<responsible></responsible>
<docno></docno>
<date></date>
<rev></rev>
</header>
<module>erlang.el</module>
<modulesummary>Erlang mode for Emacs </modulesummary>
<description>
<p>Possibly the most important feature of an editor designed for
programmers is the ability to indent a line of code in accordance
with the structure of the programming language. The Erlang mode
does, of course, provide this feature. The layout used is based
on the common use of the language. The mode also provides things as
syntax highlighting, electric commands, module name verification,
comment support including paragraph filling, skeletons, tags
support etc.</p>
<p>In the following descriptions the use of the word <em>Point</em> means: "Point can be seen as the position of the
cursor. More precisely, the point is the position between two
characters while the cursor is drawn over the character
following the point".</p>
</description>
<section>
<title>Indent</title>
<p>The following command are directly available for indentation.</p>
<list type="bulleted">
<item><em><c>TAB</c></em> (<c>erlang-indent-command</c>) -
Indents the current line of code. </item>
<item><em><c>M-C-\</c></em> (<c>indent-region</c>) - Indents all
lines in the region. </item>
<item><em><c>M-l</c></em> (<c>indent-for-comment</c>) - Insert a
comment character to the right of the code on the line (if
any).</item>
</list>
<p>Lines containing comment are indented differently depending on
the number of %-characters used: </p>
<list type="bulleted">
<item>Lines with one %-character is indented to the right of
the code. The column is specified by the variable
<c>comment-column</c>, by default column 48 is used.</item>
<item>Lines with two %-characters will be indented to the same
depth as code would have been in the same situation. </item>
<item>Lines with three of more %-characters are indented to the
left margin.</item>
<item><em><c>C-c C-q</c></em> (<c>erlang-indent-function</c>) -
Indents the current Erlang function. </item>
<item><em><c>M-x erlang-indent-clause RET</c></em> <br></br>
-Indent the
current Erlang clause.</item>
<item><em><c>M-x erlang-indent-current-buffer RET</c></em> -
Indent the entire buffer. </item>
</list>
</section>
<section>
<title>Edit - Fill Comment </title>
<p>When editing normal text in text mode you can let Emacs reformat the
text by the <c>fill-paragraph</c> command. This command will not work
for comments since it will treat the comment characters as words.</p>
<p>The Erlang editing mode provides a command that knows about the
Erlang comment structure and can be used to fill text paragraphs
in comments. Ex:</p>
<code type="none">
%% This is just a very simple test to show
%% how the Erlang fill
%% paragraph command works.</code>
<p>Clearly, the text is badly formatted. Instead of formatting this
paragraph line by line, let's try <c>erlang-fill-paragraph</c> by
pressing <em><c>M-q</c></em>. The result is:</p>
<code type="none">
%% This is just a very simple test to show how the Erlang fill
%% paragraph command works.</code>
</section>
<section>
<title>Edit - Comment/Uncomment Region </title>
<p><em><c>C-c C-c</c></em> will put comment characters at the
beginning of all lines in a marked region. If you want to have
two comment characters instead of one you can do <em><c>C-u 2 C-c C-c</c></em></p>
<p><em><c>C-c C-u</c></em> will undo a comment-region command. </p>
</section>
<section>
<title>Edit - Moving the marker </title>
<list type="bulleted">
<item><em><c>C-a M-a </c></em>
(<c>erlang-beginning-of-function</c>) - Move the point to the
beginning of the current or preceding Erlang function. With an
numeric argument (ex <em><c>C-u 2 C-a M-a</c></em>) the function
skips backwards over this many Erlang functions. Should the
argument be negative the point is moved to the beginning of a
function below the current function. </item>
<item><em><c>M-C-a </c></em> (<c>erlang-beginning-of-clause</c>) - As
above but move point to the beginning of the current or
preceding Erlang clause.</item>
<item><em><c>C-a M-e </c></em> (<c>erlang-end-of-function</c>)
- Move to the end of the current or following Erlang function. With
an numeric argument (ex <em><c>C-u 2 C-a M-e</c></em>) the function
skips backwards over this many Erlang functions. Should the argument
be negative the point is moved to the end of a function below
the current function.</item>
<item><em><c>M-C-e </c></em> (<c>erlang-end-of-clause</c>) - As above
but move point to the end of the current or following Erlang
clause.</item>
</list>
</section>
<section>
<title>Edit - Marking </title>
<list type="bulleted">
<item><em><c>C-c M-h</c></em> (<c>erlang-mark-function</c>) - Put the
region around the current Erlang function. The point is
placed in the beginning and the mark at the end of the
function.</item>
<item><em><c>M-C-h </c></em> (<c>erlang-mark-clause</c>) Put the region
around the current Erlang clause. The point is placed in the
beginning and the mark at the end of the function. </item>
</list>
</section>
<section>
<title>Edit - Function Header Commands </title>
<list type="bulleted">
<item><em><c>C-c C-j</c></em> (<c>erlang-generate-new-clause</c>) -
Create a new clause in the current Erlang function. The point is
placed between the parentheses of the argument list.</item>
<item><em><c>C-c C-y</c></em> (<c>erlang-clone-arguments</c>) -
Copy the function arguments of the preceding Erlang clause. This
command is useful when defining a new clause with almost the same
argument as the preceding.</item>
</list>
</section>
<section>
<title>Edit - Arrows</title>
<list type="bulleted">
<item>
<p><em><c>C-c C-a</c></em> (<c>erlang-align-arrows</c>) -
aligns arrows after clauses inside a region.</p>
<code type="none">
Example:
sum(L) -> sum(L, 0).
sum([H|T], Sum) -> sum(T, Sum + H);
sum([], Sum) -> Sum.
becomes:
sum(L) -> sum(L, 0).
sum([H|T], Sum) -> sum(T, Sum + H);
sum([], Sum) -> Sum.</code>
</item>
</list>
</section>
<section>
<title>Syntax highlighting</title>
<p>The syntax highlighting can be activated from the Erlang menu. There
are four different alternatives:</p>
<list type="bulleted">
<item>Off: Normal black and white display.
</item>
<item>Level 1: Function headers, reserved words, comments,
strings, quoted atoms, and character constants will be
colored. </item>
<item>Level 2: The above, attributes, Erlang bif:s, guards, and
words in comments enclosed in single quotes will be colored.</item>
<item>Level 3: The above, variables, records, and macros will
be colored. (This level is also known as the Christmas tree
level.) </item>
</list>
</section>
<section>
<title>Tags</title>
<p>For the tag commands to work it requires that you have
generated a tag file. See <seealso marker="erlang_mode_chapter#tags">Erlang mode users guide</seealso></p>
<p></p>
<list type="bulleted">
<item><em><c>M-. </c></em> (<c>find-tag</c>) -
Find a function definition. The default value is the function name
under the point. </item>
<item>Find Tag (<c>erlang-find-tag</c>) - Like the Elisp-function
`find-tag'. Capable of retrieving Erlang modules. Tags can be
given on the forms `tag', `module:', `module:tag'.</item>
<item><em><c>M-+</c></em> (<c>erlang-find-next-tag</c>) - Find the
next occurrence of tag.</item>
<item><em><c>M-TAB</c></em> (<c>erlang-complete-tag</c>) -
Perform completion on the tag entered in a tag search.
Completes to the set of names listed in the current tags table.</item>
<item>Tags aprops (<c>tags-apropos</c>) - Display list of all tags in
tags table REGEXP matches. </item>
<item><em><c>C-x t s</c></em> (<c>tags-search</c>) - Search
through all files listed in tags table for match for REGEXP.
Stops when a match is found.</item>
</list>
</section>
<section>
<title>Skeletons</title>
<p>A skeleton is a piece of pre-written code that can be inserted into
the buffer. Erlang mode comes with a set of predefined skeletons.
The skeletons can be accessed either from the Erlang menu of
from commands named <c>tempo-template-erlang-*</c>, as the
skeletons is defined using the standard Emacs package "tempo".
Here follows a brief description of the available skeletons:</p>
<list type="bulleted">
<item>Simple skeletons: If, Case, Receive, Receive After,
Receive Loop - Basic code constructs.
</item>
<item>Header elements: Module, Author - These commands insert
lines on the form <c>-module(</c>xxx<c>). </c> and
<c>-author('my@home').</c>. They can be used directly, but are
also used as part of the full headers described below.</item>
<item>Full Headers: Small (minimum requirement), Medium (with
fields for basic information about the module), and Large
Header (medium header with some extra layout structure).</item>
<item>Small Server - skeleton for a simple server not using
OTP.</item>
<item>Application - skeletons for the OTP application
behavior</item>
<item>Supervisor - skeleton for the OTP supervisor behavior</item>
<item>Supervisor Bridge - skeleton for the OTP supervisor bridge
behavior </item>
<item>gen_server - skeleton for the OTP gen_server
behavior</item>
<item>gen_event - skeleton for the OTP gen_event behavior</item>
<item>gen_fsm - skeleton for the OTP gen_fsm behavior</item>
<item>Library module - skeleton for a module that does not
implement a process.</item>
<item>Corba callback - skeleton for a Corba callback module.</item>
<item>Erlang test suite - skeleton for a callback module
for the erlang test server.</item>
</list>
</section>
<section>
<title>Shell</title>
<list type="bulleted">
<item>New shell (<c>erlang-shell</c>) - Starts a new Erlang shell.</item>
<item><em><c>C-c C-z,</c></em> (<c>erlang-shell-display </c>) -
Displays an Erlang shell, or starts a new one if there is no shell
started.</item>
</list>
</section>
<section>
<title>Compile</title>
<list type="bulleted">
<item><em><c>C-c C-k,</c></em> (<c>erlang-compile</c>) -
Compiles the Erlang module in the current buffer.
You can also use <em><c>C-u C-c C-k</c></em>
to debug compile the module with the debug options
<c>debug_info</c> and <c>export_all</c>.</item>
<item><em><c>C-c C-l,</c></em> (<c>erlang-compile-display</c>) -
Display compilation output.</item>
<item><em><c>C-u C-x`</c></em> Start parsing the compiler output from the
beginning. This command will place the point on the line where
the first error was found.</item>
<item><em><c>C-x`</c></em> (<c>erlang-next-error</c>) - Move the
point on to the next error. The buffer displaying the
compilation errors will be updated so that the current error
will be visible.</item>
</list>
</section>
<section>
<title>Man</title>
<p>On unix you can view the manual pages in emacs.
In order to find the manual pages, the variable `erlang-root-dir'
should be bound to the name of the directory containing the Erlang
installation. The name should not include the final slash.
Practically, you should add a line on the following form to
your ~/.emacs,</p>
<code type="none">
(setq erlang-root-dir "/the/erlang/root/dir/goes/here")</code>
</section>
<section>
<title>Starting IMenu</title>
<list type="bulleted">
<item><em><c>M-x imenu-add-to-menubar RET</c></em> - This
command will create the IMenu menu containing all the functions
in the current buffer.The command will ask you for a suitable
name for the menu. Not supported by Xemacs.</item>
</list>
</section>
<section>
<title>Version</title>
<list type="bulleted">
<item><em><c>M-x erlang-version RET</c></em> -
This command displays the version number of the Erlang editing mode.
Remember to always supply the version number when asking questions
about the Erlang mode.</item>
</list>
</section>
</erlref>
