rfc:scalar_type_hints

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rfc:scalar_type_hints [2015/02/05 20:04] – Voting. ajfrfc:scalar_type_hints [2017/09/22 13:28] (current) – external edit 127.0.0.1
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 ====== PHP RFC: Scalar Type Hints ====== ====== PHP RFC: Scalar Type Hints ======
-  * Version: 0.3 +  * Version: 0.3.1 
-  * Date: 2014-12-14 (initial draft; put Under Discussion 2014-12-31; version 0.2 created 2015-01-13)+  * Date: 2014-12-14 (initial draft; put Under Discussion 2014-12-31; version 0.2 created 2015-01-13; withdrawn 2015-02-15)
   * Author: Andrea Faulds, ajf@ajf.me   * Author: Andrea Faulds, ajf@ajf.me
-  * Status: Voting+  * Status: Withdrawn
   * First Published at: http://wiki.php.net/rfc/scalar_type_hints   * First Published at: http://wiki.php.net/rfc/scalar_type_hints
  
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 ==== History ==== ==== History ====
  
-PHP has had parameter type hints for class names since PHP 5.0, arrays since PHP 5.1 and callables since PHP 5.4. These type hints allow the PHP runtime to ensure that correctly-typed arguments are passed to functions, and make function signatures more informative. Unfortunately, PHP's scalar types haven't been hintable.+PHP has had parameter type hints for interface and class names since PHP 5.0, arrays since PHP 5.1 and callables since PHP 5.4. These type hints allow the PHP runtime to ensure that correctly-typed arguments are passed to functions, and make function signatures more informative. Unfortunately, PHP's scalar types haven't been hintable.
  
 There have been some previous attempts at adding scalar type hints, such as the [[rfc:scalar_type_hinting_with_cast|Scalar Type Hints with Casts]] RFC. From what I can see, that specific RFC failed primarily for three reasons: There have been some previous attempts at adding scalar type hints, such as the [[rfc:scalar_type_hinting_with_cast|Scalar Type Hints with Casts]] RFC. From what I can see, that specific RFC failed primarily for three reasons:
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 This doesn't affect the behaviour of cast operators. This doesn't affect the behaviour of cast operators.
  
-When the strict type-checking mode isn't in use (which is the default), function calls behave identically to previous PHP versions.+When the strict type-checking mode isn't in use (which is the default), function calls to built-in and extension PHP functions behave identically to previous PHP versions.
  
 ===== Open Issues ===== ===== Open Issues =====
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 Because scalar type hints guarantee that a passed argument will be of a certain type within a function body (at least initially), this could be used in the Zend Engine for optimisations. For example, if a function takes two ''float''-hinted arguments and does arithmetic with them, there is no need for the arithmetic operators to check the types of their operands. As I understand it, HHVM already does such optimisations, and might benefit from this RFC. Because scalar type hints guarantee that a passed argument will be of a certain type within a function body (at least initially), this could be used in the Zend Engine for optimisations. For example, if a function takes two ''float''-hinted arguments and does arithmetic with them, there is no need for the arithmetic operators to check the types of their operands. As I understand it, HHVM already does such optimisations, and might benefit from this RFC.
 +
 +In discussions around this RFC, the ''declare(strict_types=1);'' syntax has been controversial. It is arguably rather ugly, and it has all the scoping quirks of ''declare()''. I've now arrived at a point where I'm willing to change to a truly per-file syntax, ''<?php strict'' (or similar). However, the RFC is currently being voted on, and I'd rather not cancel the vote. So, this will be proposed in a subsequent RFC.
 +
 +Another issue that came up is PHP's lack of a typehint for numbers (which also came up with the previous Scalar Type Hinting with Cast RFC). I plan to propose a ''numeric'' typehint in a future RFC which would take either an integer or a float.
  
 ===== Vote ===== ===== Vote =====
  
-As this is a language change, this RFC requires a 2/3 majority to pass. Voting for all three votes started on 2015-02-05 and all end on 2015-02-19. +As this is a language change, this RFC requires a 2/3 majority to pass. Voting for all three votes started on 2015-02-05 and all were to end on 2015-02-19, but the voting was cancelled and the RFC withdrawn on 2015-02-15.
  
-The following vote is for the RFC itself.+==== Main ====
  
-<doodle title="Accept the Scalar Type Hints RFC and merge patch into master?" auth="ajf" voteType="single" closed="false">+This vote is for the RFC itself. 
 + 
 +<doodle title="Accept the Scalar Type Hints RFC and merge patch into master?" auth="ajf" voteType="single" closed="true">
    * Yes    * Yes
    * No    * No
 </doodle> </doodle>
  
-The following vote is to solve the open issue regarding the ''integer'' and ''boolean'' synonyms for ''int'' and ''bool''. Whichever option receives the most votes will be implemented.+==== Type aliases ====
  
-<doodle title="Type aliases" auth="ajf" voteType="single" closed="false">+This second vote is to solve the open issue regarding the ''integer'' and ''boolean'' synonyms for ''int'' and ''bool''. Whichever option receives the most votes will be implemented. 
 + 
 +<doodle title="Type aliases" auth="ajf" voteType="single" closed="true">
    * Allow synonyms    * Allow synonyms
    * Reserve synonyms and produce error message when used    * Reserve synonyms and produce error message when used
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 </doodle> </doodle>
  
-The following vote is in case the RFC fails to pass. It's a 2/3 majority-required backwards compatibility-breaking language change, which is to reserve the type hint names proposed by the RFC, so that a future RFC could implement scalar type hints without requiring a backwards compatibility break. The type names reserved include the synonyms ''integer'' and ''boolean''. They would not be reserved words, merely prohibited from use as class/interface/trait names, like this RFC's type names.+==== Reserve for future use ==== 
 + 
 +This final vote is in case the RFC fails to pass. It's a 2/3 majority-required backwards compatibility-breaking language change, which is to reserve the type hint names proposed by the RFC, so that a future RFC could implement scalar type hints without requiring a backwards compatibility break. The type names reserved include the synonyms ''integer'' and ''boolean''. They would not be reserved words, merely prohibited from use as class/interface/trait names, like this RFC's type names.
  
-<doodle title="Reserve type names if RFC does not pass?" auth="ajf" voteType="single" closed="false">+<doodle title="Reserve type names if RFC does not pass?" auth="ajf" voteType="single" closed="true">
    * Yes    * Yes
    * No    * No
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 ===== Changelog ===== ===== Changelog =====
  
 +  * v0.3.1 - Noted ''numeric'' and syntax change in Future Scope
   * v0.3 - Return types support   * v0.3 - Return types support
   * v0.2.3 - ''strict_types=1'' rather than ''strict_typehints=TRUE''   * v0.2.3 - ''strict_types=1'' rather than ''strict_typehints=TRUE''
rfc/scalar_type_hints.1423166673.txt.gz · Last modified: 2017/09/22 13:28 (external edit)

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