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authorHans Bolinder <[email protected]>2014-03-25 14:08:30 +0100
committerHans Bolinder <[email protected]>2014-03-26 11:48:01 +0100
commit9dfc9857ff5089282f97656fe59012c26ccae52a (patch)
treefdc255243451d023438c0ea0f827d90c68e2739a /system/doc
parent97039a7b78cfcb42bfcd86bc97490ea28df37603 (diff)
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refman: Clarify the '-callback' attribute
Diffstat (limited to 'system/doc')
-rw-r--r--system/doc/design_principles/spec_proc.xml16
-rw-r--r--system/doc/reference_manual/modules.xml19
2 files changed, 24 insertions, 11 deletions
diff --git a/system/doc/design_principles/spec_proc.xml b/system/doc/design_principles/spec_proc.xml
index 69bf2e0448..e4fb5fdca7 100644
--- a/system/doc/design_principles/spec_proc.xml
+++ b/system/doc/design_principles/spec_proc.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>1997</year><year>2013</year>
+ <year>1997</year><year>2014</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -431,11 +431,11 @@ loop(...) ->
<section>
<title>User-Defined Behaviours</title>
- <p>To implement a user-defined behaviour, write code similar to
+ <p><marker id="behaviours"/>To implement a user-defined behaviour, write code similar to
code for a special process but calling functions in a callback
module for handling specific tasks.</p>
<p>If it is desired that the compiler should warn for missing callback
- functions, as it does for the OTP behaviours, add callback attributes in the
+ functions, as it does for the OTP behaviours, add <c>-callback</c> attributes in the
behaviour module to describe the expected callbacks:</p>
<code type="none">
-callback Name1(Arg1_1, Arg1_2, ..., Arg1_N1) -> Res1.
@@ -445,15 +445,15 @@ loop(...) ->
<p>where <c>NameX</c> are the names of the expected callbacks and
<c>ArgX_Y</c>, <c>ResX</c> are types as they are described in Specifications
for functions in <seealso marker="../reference_manual/typespec">Types and
- Function Specifications</seealso>. The whole syntax of spec attributes is
- supported by callback attributes.</p>
+ Function Specifications</seealso>. The whole syntax of <c>-spec</c> attribute is
+ supported by <c>-callback</c> attribute.</p>
<p>Alternatively you may directly implement and export the function:</p>
<code type="none">
behaviour_info(callbacks) ->
- [{Name1,Arity1},...,{NameN,ArityN}].</code>
- <p>where each <c>{Name,Arity}</c> specifies the name and arity of a callback
+ [{Name1, Arity1},...,{NameN, ArityN}].</code>
+ <p>where each <c>{Name, Arity}</c> specifies the name and arity of a callback
function. This function is otherwise automatically generated by the compiler
- using the callback attributes.</p>
+ using the <c>-callback</c> attributes.</p>
<p>When the compiler encounters the module attribute
<c>-behaviour(Behaviour).</c> in a module <c>Mod</c>, it will call
<c>Behaviour:behaviour_info(callbacks)</c> and compare the result with the
diff --git a/system/doc/reference_manual/modules.xml b/system/doc/reference_manual/modules.xml
index 9e5f4de385..cd4c3a1b1b 100644
--- a/system/doc/reference_manual/modules.xml
+++ b/system/doc/reference_manual/modules.xml
@@ -4,7 +4,7 @@
<chapter>
<header>
<copyright>
- <year>2003</year><year>2013</year>
+ <year>2003</year><year>2014</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
@@ -134,8 +134,21 @@ fact(0) -> % |
standard behaviours <c>gen_server</c>, <c>gen_fsm</c>,
<c>gen_event</c> or <c>supervisor</c>.</p>
<p>The spelling <c>behavior</c> is also accepted.</p>
- <p>Read more about behaviours and callback modules in OTP Design
- Principles.</p>
+ <p>The callback functions of the module can be specified either
+ directly by the exported function <c>behaviour_info/1</c>:</p>
+ <pre>
+behaviour_info(callbacks) -> Callbacks.</pre>
+ <p>or by a <c>-callback</c> attribute for each callback
+ function:</p>
+ <pre>
+-callback Name(Arguments) -> Result.</pre>
+ <p>where <c>Arguments</c> is a list of zero or more arguments.
+ The <c>-callback</c> attribute is to be preferred since the
+ extra type information can be used by tools to produce
+ documentation or find discrepancies.</p>
+ <p>Read more about behaviours and callback modules in
+ <seealso marker="doc/design_principles:spec_proc#behaviours">
+ OTP Design Principles</seealso>.</p>
</section>
<section>