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File 0334-erlang_fun_to_list-1-Improvements-due-to-comments-fr.patch of Package erlang
From 69986f99ad0840f9a15e811ba202db4efa3e99c3 Mon Sep 17 00:00:00 2001 From: Kjell Winblad <kjellwinblad@gmail.com> Date: Tue, 29 Sep 2020 11:24:25 +0200 Subject: [PATCH 34/39] erlang_fun_to_list/1: Improvements due to comments from @bjorng * Change structure * Warnings to notes * Add example --- erts/doc/src/erlang.xml | 103 +++++++++++++++++++++++++++++----------- 1 file changed, 74 insertions(+), 29 deletions(-) diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml index 7bce904b69..d46df36345 100644 --- a/erts/doc/src/erlang.xml +++ b/erts/doc/src/erlang.xml @@ -2123,43 +2123,88 @@ true</pre> <name name="fun_to_list" arity="1" since=""/> <fsummary>Text representation of a fun.</fsummary> <desc> - <warning> - <p>This function is <em>not</em> guaranteed to work as described here - when <c><anno>Fun</anno></c> was created while executing - uncompiled code (uncompiled escripts, the Erlang shell, and - other code executed by the <seeerl - marker="stdlib:erl_eval"><c>erl_eval</c> module</seeerl>).</p> - </warning> - <p>Returns <c><anno>String</anno></c> that represents the code + <p>Returns <c><anno>String</anno></c> that represents the code that created <c><anno>Fun</anno></c>.</p> - <warning> - <p>Generally, one can not use this function to check if two - funs are equal as this function does not take the fun's - environment into account. See <seemfa - marker="#fun_info/1"><c>erlang:fun_info/1</c></seemfa> for how - to get the environment of a fun.</p> - </warning> - <note> - <p><c><anno>String</anno></c> has the following form, if - <c><anno>Fun</anno></c> was created by an expression of the - form <c>fun ModuleName:FuncName/Arity</c>:</p> - <p><c>"fun ModuleName:FuncName/Arity"</c>,</p> - <p>and <c><anno>String</anno></c> has the following form, if - <c><anno>Fun</anno></c> was created by a <seeguide - marker="system/reference_manual:expressions#fun-expressions">fun - expression</seeguide>:</p> + <p><c><anno>String</anno></c> has the following form, if + <c><anno>Fun</anno></c> was created by a <seeguide + marker="system/reference_manual:expressions#fun-expressions">fun + expression</seeguide> of the form <c>fun + ModuleName:FuncName/Arity</c>:</p> + + <p><c>"fun ModuleName:FuncName/Arity"</c></p> - <p><c>"#Fun<M.I.U>"</c>, where M, I and U correspond to - the values named <c>module</c>, <c>index</c> and <c>uniq</c> - in the result of <seemfa - marker="#fun_info/1"><c>erlang:fun_info(Fun)</c></seemfa>.</p> + <p>The form of <c><anno>String</anno></c> when + <c><anno>Fun</anno></c> is created from other types of <seeguide + marker="system/reference_manual:expressions#fun-expressions">fun + expressions</seeguide> differs depending on if the fun + expression was executed while executing compiled code or if + the fun expression was executed while executing uncompiled + code (uncompiled escripts, the Erlang shell, and other code + executed by the erl_eval module):</p> + <taglist> + <tag>compiled code</tag> + <item><p><c>"#Fun<M.I.U>"</c>, where M, I and U + correspond to the values named <c>module</c>, <c>index</c> + and <c>uniq</c> in the result of <seemfa + marker="#fun_info/1"><c>erlang:fun_info(Fun)</c></seemfa>.</p></item> + <tag>uncompiled code</tag> + + <item>All funs created from fun expressions in uncompiled + code with the same arity are mapped to the same list by + <c>fun_to_list/1</c>.</item> + </taglist> + + + <note> + <p>Generally, one can not use <c>fun_to_list/1</c> to check if + two funs are equal as <c>fun_to_list/1</c> does not take the + fun's environment into account. See <seemfa + marker="#fun_info/1"><c>erlang:fun_info/1</c></seemfa> for how + to get the environment of a fun.</p> + </note> + <note> <p>The output of <c>fun_to_list/1</c> can differ between - Erlang implementations and can change in future + Erlang implementations and may change in future versions.</p> </note> + <p>Examples:</p> + <code> +-module(test). +-export([add/1, add2/0, fun_tuple/0]). +add(A) -> fun(B) -> A + B end. +add2() -> fun add/1. +fun_tuple() -> {fun() -> 1 end, fun() -> 1 end}. + </code> +<pre> +> <input>{fun test:add/1, test:add2()}.</input> +{fun test:add/1,#Fun<test.1.107738983>} +</pre> +<p> + Explanation: <c>fun test:add/1</c> is upgradable but <c>test:add2()</c> is not upgradable. +</p> +<pre> +> <input>{test:add(1), test:add(42)}.</input> +{#Fun<test.0.107738983>,#Fun<test.0.107738983>} +</pre> +<p>Explanation: <c>test:add(1)</c> and <c>test:add(42)</c> has the +same string representation as the environment is not taken into +account.</p> +<pre> +><input>test:fun_tuple().</input> +{#Fun<test.2.107738983>,#Fun<test.3.107738983>} +</pre> +<p>Explanation: The string representations differ because the funs +come from different fun experssions.</p> +<pre> +> <input>{fun() -> 1 end, fun() -> 1 end}.</input> > <input></input> +{#Fun<erl_eval.45.97283095>,#Fun<erl_eval.45.97283095>} +</pre> +<p>Explanation: All funs created from fun expressions of this form in +uncompiled code with the same arity are mapped to the same list by +<c>fun_to_list/1</c>.</p> </desc> </func> -- 2.26.2
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