rfc:final_class_const

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rfc:final_class_const [2021/04/23 17:14] – kocsismaterfc:final_class_const [2021/07/06 20:52] (current) – kocsismate
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   * Date: 2021-04-23   * Date: 2021-04-23
   * Author: Máté Kocsis <kocsismate@php.net>   * Author: Máté Kocsis <kocsismate@php.net>
-  * Status: Under discussion+  * Status: Implemented
   * Implementation: https://github.com/php/php-src/pull/6878   * Implementation: https://github.com/php/php-src/pull/6878
 +  * Target Version: PHP 8.1
  
 ===== Introduction ===== ===== Introduction =====
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 First of all, the engine can't optimize class constant references when late static binding is involved, so it has to pessimistically assume that ''FOO'' is overridden in case of ''static::FOO'' or ''$this::FOO'' invocations. First of all, the engine can't optimize class constant references when late static binding is involved, so it has to pessimistically assume that ''FOO'' is overridden in case of ''static::FOO'' or ''$this::FOO'' invocations.
  
-What's more important is that one cannot make sure that class constant values stay constant. Even if one always references them by using ''self::'', doing so won't prevent a child class from changing them. Although constants not being constants is usually considered only as a theoretical problem, being able to add a ''final'' modifier would make the intention explicit that child classes shouldn't try to override them.+What's more important is that class constants are not guaranteed to stay constant. Even if the declaring class always references them by using ''self::'', doing so won't prevent a child class from changing their value or even their type, unless the parent is a final class. Although constants not being constants is usually considered only as a theoretical problem, being able to add a ''final'' modifier would make the intention explicit that child classes shouldn't try to override them (e.g. because the parent doesn't use late static binding).
  
-An interesting fact is that interface constants are already ''final'':+A related interesting fact is that interface constants are already ''final'':
  
 <code php> <code php>
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 </code> </code>
  
-This leads to an interesting inconsistency. By introducing an intermediate class, overriding still becomes possible:+This leads to a weird inconsistency. By introducing an intermediate class, overriding still becomes possible:
  
 <code php> <code php>
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 ===== Proposal ===== ===== Proposal =====
  
-The final modifier can be added to class constants. Doing so prevents a constant to be overridden in a child class:+The final modifier can be added to class constants. Doing so prevents overriding of a constant:
  
 <code php> <code php>
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 ===== Reflection ===== ===== Reflection =====
  
-A ''ReflectionClassConstant::isFinal()''method is added in order to be able to retrieve if a constant is final.+A ''ReflectionClassConstant::isFinal()'' method is added in order to be able to retrieve if a constant is final.
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
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 ===== Vote ===== ===== Vote =====
  
-Add support for final class constants? The vote requires 2/3 majority to be accepted.+Voting started on 2021-05-19 08:00 UTC and ends 2021-06-02 08:00 UTC. The vote requires 2/3 majority to be accepted. 
 + 
 +<doodle title="Add support for final class constants?" auth="kocsismate" voteType="single" closed="true"> 
 +   * Yes 
 +   * No 
 +</doodle>
  
  
  
rfc/final_class_const.1619198071.txt.gz · Last modified: 2021/04/23 17:14 by kocsismate

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