1erlang.el(3) Erlang Module Definition erlang.el(3)
2
6 erlang.el - Erlang mode for Emacs
7
9 Possibly the most important feature of an editor designed for program‐
10 mers is the ability to indent a line of code in accordance with the
11 structure of the programming language. The Erlang mode does, of course,
12 provide this feature. The layout used is based on the common use of the
13 language. The mode also provides things as syntax highlighting, elec‐
14 tric commands, module name verification, comment support including
15 paragraph filling, skeletons, tags support etc.
16 In the following descriptions the use of the word Point means: "Point
18 can be seen as the position of the cursor. More precisely, the point is
19 the position between two characters while the cursor is drawn over the
20 character following the point".
21
23 The following command are directly available for indentation.
24 * TAB (erlang-indent-command) - Indents the current line of code.
26 * M-C-\ (indent-region) - Indents all lines in the region.
28 * M-l (indent-for-comment) - Insert a comment character to the right
30 of the code on the line (if any).
31 Lines containing comment are indented differently depending on the num‐
33 ber of %-characters used:
34 * Lines with one %-character is indented to the right of the code.
36 The column is specified by the variable comment-column, by default
37 column 48 is used.
38 * Lines with two %-characters will be indented to the same depth as
40 code would have been in the same situation.
41 * Lines with three of more %-characters are indented to the left mar‐
43 gin.
44 * C-c C-q (erlang-indent-function) - Indents the current Erlang func‐
46 tion.
47 * M-x erlang-indent-clause RET
49 -Indent the current Erlang clause.
50 * M-x erlang-indent-current-buffer RET - Indent the entire buffer.
52
54 When editing normal text in text mode you can let Emacs reformat the
55 text by the fill-paragraph command. This command will not work for com‐
56 ments since it will treat the comment characters as words.
57 The Erlang editing mode provides a command that knows about the Erlang
59 comment structure and can be used to fill text paragraphs in comments.
60 Ex:
61 %% This is just a very simple test to show
63 %% how the Erlang fill
64 %% paragraph command works.
65 Clearly, the text is badly formatted. Instead of formatting this para‐
67 graph line by line, let's try erlang-fill-paragraph by pressing M-q.
68 The result is:
69 %% This is just a very simple test to show how the Erlang fill
71 %% paragraph command works.
72
74 C-c C-c will put comment characters at the beginning of all lines in a
75 marked region. If you want to have two comment characters instead of
76 one you can do C-u 2 C-c C-c
77 C-c C-u will undo a comment-region command.
79
81 * C-a M-a (erlang-beginning-of-function) - Move the point to the be‐
82 ginning of the current or preceding Erlang function. With an nu‐
83 meric argument (ex C-u 2 C-a M-a) the function skips backwards over
84 this many Erlang functions. Should the argument be negative the
85 point is moved to the beginning of a function below the current
86 function.
87 * M-C-a (erlang-beginning-of-clause) - As above but move point to
89 the beginning of the current or preceding Erlang clause.
90 * C-a M-e (erlang-end-of-function) - Move to the end of the current
92 or following Erlang function. With an numeric argument (ex C-u 2 C-
93 a M-e) the function skips backwards over this many Erlang func‐
94 tions. Should the argument be negative the point is moved to the
95 end of a function below the current function.
96 * M-C-e (erlang-end-of-clause) - As above but move point to the end
98 of the current or following Erlang clause.
99
101 * C-c M-h (erlang-mark-function) - Put the region around the current
102 Erlang function. The point is placed in the beginning and the mark
103 at the end of the function.
104 * M-C-h (erlang-mark-clause) Put the region around the current Er‐
106 lang clause. The point is placed in the beginning and the mark at
107 the end of the function.
108
110 * C-c C-j (erlang-generate-new-clause) - Create a new clause in the
111 current Erlang function. The point is placed between the parenthe‐
112 ses of the argument list.
113 * C-c C-y (erlang-clone-arguments) - Copy the function arguments of
115 the preceding Erlang clause. This command is useful when defining a
116 new clause with almost the same argument as the preceding.
117
119 * C-c C-a (erlang-align-arrows) - aligns arrows after clauses inside
120 a region.
121 Example:
123 sum(L) -> sum(L, 0).
125 sum([H|T], Sum) -> sum(T, Sum + H);
126 sum([], Sum) -> Sum.
127 becomes:
129 sum(L) -> sum(L, 0).
131 sum([H|T], Sum) -> sum(T, Sum + H);
132 sum([], Sum) -> Sum.
133
135 The syntax highlighting can be activated from the Erlang menu. There
136 are four different alternatives:
137 * Off: Normal black and white display.
139 * Level 1: Function headers, reserved words, comments, strings,
141 quoted atoms, and character constants will be colored.
142 * Level 2: The above, attributes, Erlang bif:s, guards, and words in
144 comments enclosed in single quotes will be colored.
145 * Level 3: The above, variables, records, and macros will be colored.
147 (This level is also known as the Christmas tree level.)
148
150 For the tag commands to work it requires that you have generated a tag
151 file. See Erlang mode users guide
152 * M-. (find-tag) - Find a function definition. The default value is
154 the function name under the point.
155 * Find Tag (erlang-find-tag) - Like the Elisp-function `find-tag'.
157 Capable of retrieving Erlang modules. Tags can be given on the
158 forms `tag', `module:', `module:tag'.
159 * M-+ (erlang-find-next-tag) - Find the next occurrence of tag.
161 * M-TAB (erlang-complete-tag) - Perform completion on the tag entered
163 in a tag search. Completes to the set of names listed in the cur‐
164 rent tags table.
165 * Tags aprops (tags-apropos) - Display list of all tags in tags table
167 REGEXP matches.
168 * C-x t s (tags-search) - Search through all files listed in tags ta‐
170 ble for match for REGEXP. Stops when a match is found.
171
173 A skeleton is a piece of pre-written code that can be inserted into the
174 buffer. Erlang mode comes with a set of predefined skeletons. The
175 skeletons can be accessed either from the Erlang menu of from commands
176 named tempo-template-erlang-*, as the skeletons is defined using the
177 standard Emacs package "tempo". Here follows a brief description of the
178 available skeletons:
179 * Simple skeletons: If, Case, Receive, Receive After, Receive Loop -
181 Basic code constructs.
182 * Header elements: Module, Author - These commands insert lines on
184 the form -module(xxx). and -author('my@home').. They can be used
185 directly, but are also used as part of the full headers described
186 below.
187 * Full Headers: Small (minimum requirement), Medium (with fields for
189 basic information about the module), and Large Header (medium
190 header with some extra layout structure).
191 * Small Server - skeleton for a simple server not using OTP.
193 * Application - skeletons for the OTP application behavior
195 * Supervisor - skeleton for the OTP supervisor behavior
197 * Supervisor Bridge - skeleton for the OTP supervisor bridge behavior
199 * gen_server - skeleton for the OTP gen_server behavior
201 * gen_event - skeleton for the OTP gen_event behavior
203 * gen_fsm - skeleton for the OTP gen_fsm behavior
205 *
207 gen_statem (StateName/3) - skeleton for the OTP gen_statem behav‐
208 ior using state name functions
209 *
211 gen_statem (handle_event/4) - skeleton for the OTP gen_statem be‐
212 havior using one state function
213 * Library module - skeleton for a module that does not implement a
215 process.
216 * Corba callback - skeleton for a Corba callback module.
218 * Erlang test suite - skeleton for a callback module for the erlang
220 test server.
221
223 * New shell (erlang-shell) - Starts a new Erlang shell.
224 * C-c C-z, (erlang-shell-display ) - Displays an Erlang shell, or
226 starts a new one if there is no shell started.
227
229 * C-c C-k, (erlang-compile) - Compiles the Erlang module in the cur‐
230 rent buffer. You can also use C-u C-c C-k to debug compile the mod‐
231 ule with the debug options debug_info and export_all.
232 * C-c C-l, (erlang-compile-display) - Display compilation output.
234 * C-u C-x` Start parsing the compiler output from the beginning. This
236 command will place the point on the line where the first error was
237 found.
238 * C-x` (erlang-next-error) - Move the point on to the next error. The
240 buffer displaying the compilation errors will be updated so that
241 the current error will be visible.
242
244 On unix you can view the manual pages in emacs. In order to find the
245 manual pages, the variable `erlang-root-dir' should be bound to the
246 name of the directory containing the Erlang installation. The name
247 should not include the final slash. Practically, you should add a line
248 on the following form to your ~/.emacs,
249 (setq erlang-root-dir "/the/erlang/root/dir/goes/here")
251
253 * M-x imenu-add-to-menubar RET - This command will create the IMenu
254 menu containing all the functions in the current buffer.The command
255 will ask you for a suitable name for the menu. Not supported by
256 Xemacs.
257
259 * M-x erlang-version RET - This command displays the version number
260 of the Erlang editing mode. Remember to always supply the version
261 number when asking questions about the Erlang mode.
262Ericsson AB tools 3.5.1 erlang.el(3)