rfc:scalar_type_hints

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rfc:scalar_type_hints [2015/02/05 20:32] – Split Vote into sections ajfrfc:scalar_type_hints [2015/02/14 01:17] – ajf
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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)
   * Author: Andrea Faulds, ajf@ajf.me   * Author: Andrea Faulds, ajf@ajf.me
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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 =====
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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.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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