path: root/lib/stdlib/doc/src/erl_id_trans.xml

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>1996</year>
      <year>2016</year>
      <holder>Ericsson AB, All Rights Reserved</holder>
    </copyright>
    <legalnotice>
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
 
      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>erl_id_trans</title>
    <prepared>Robert Virding</prepared>
    <responsible>Bjarne D&auml;cker</responsible>
    <docno>1</docno>
    <approved>Bjarne D&auml;cker</approved>
    <checked></checked>
    <date>97-01-21</date>
    <rev>B</rev>
    <file>erl_id_trans.sgml</file>
  </header>
  <module>erl_id_trans</module>
  <modulesummary>An Identity Parse Transform</modulesummary>
  <description>
    <p>This module performs an identity parse transformation of Erlang code.
      It is included as an example for users who may wish to write their own
      parse transformers. If the option <c>{parse_transform,Module}</c> is passed
      to the compiler, a user written function <c>parse_transform/2</c>
      is called by the compiler before the code is checked for
      errors.</p>
  </description>
  <funcs>
    <func>
      <name>parse_transform(Forms, Options) -> Forms</name>
      <fsummary>Transform Erlang forms</fsummary>
      <type>
        <v>Forms = [<seealso marker="erl_parse#type-abstract_form">erl_parse:abstract_form()</seealso>
          | <seealso marker="erl_parse#type-form_info">erl_parse:form_info()</seealso>]</v>
        <v>Options = [<seealso marker="compile#type-option">compile:option()</seealso>]</v>
      </type>
      <desc>
        <p>Performs an identity transformation on Erlang forms, as an example.</p>
      </desc>
    </func>
  </funcs>

  <section>
    <title>Parse Transformations</title>
    <p>Parse transformations are used if a programmer wants to use
      Erlang syntax, but with different semantics. The original Erlang
      code is then transformed into other Erlang code.
      </p>
    <note>
      <p>Programmers are strongly advised not to engage in parse transformations and no support is offered for problems encountered.</p>
    </note>
  </section>

  <section>
    <title>See Also</title>
    <p><seealso marker="erl_parse">erl_parse(3)</seealso>,
    <seealso marker="compiler:compile">compile(3)</seealso>.</p>
  </section>
</erlref>