rfc:calltimebyref

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rfc:calltimebyref [2008/05/21 13:03] sfoxrfc:calltimebyref [2017/09/22 13:28] (current) – external edit 127.0.0.1
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   * Date: 2008-05-21   * Date: 2008-05-21
   * Author: Steph Fox <sfox@php.net>   * Author: Steph Fox <sfox@php.net>
-  * Status: Under Discussion+  * Status: Implemented
   * First Published at: http://wiki.php.net/rfc/calltimebyref   * First Published at: http://wiki.php.net/rfc/calltimebyref
  
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 This RFC aims to clarify the situation with call-time pass-by-ref in PHP 5.3. This RFC aims to clarify the situation with call-time pass-by-ref in PHP 5.3.
 +
 +
  
 ===== History ===== ===== History =====
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 Before PHP 4.0 was released, ''allow_call_time_pass_reference'' was introduced as a means of retaining back compatibility with PHP 3, at the point where returning by reference from a function declaration became possible [1]. By default, the INI switch has been On since inception [2]. The warning (formerly ''E_COMPILE_WARNING'' but currently ''E_DEPRECATED'') is only thrown if the INI switch is Off. You therefore need to **explicitly** switch off the directive in order to discover that the behaviour is deprecated. Before PHP 4.0 was released, ''allow_call_time_pass_reference'' was introduced as a means of retaining back compatibility with PHP 3, at the point where returning by reference from a function declaration became possible [1]. By default, the INI switch has been On since inception [2]. The warning (formerly ''E_COMPILE_WARNING'' but currently ''E_DEPRECATED'') is only thrown if the INI switch is Off. You therefore need to **explicitly** switch off the directive in order to discover that the behaviour is deprecated.
  
-At the time ''allow_call_time_pass_reference'' was introduced, php.ini-recommended was interestingly referred to as 'php.ini-optimized'. Over the years, it has become fairly standard to regard php.ini-recommended as 'production settings'; things like ''display_errors=Off'' and ''log_errors=On'' have helped this perception along. For the last 8 years, therefore, the first anyone is likely to have known about their code being less than kosher is when it went live.+At the time ''allow_call_time_pass_reference'' was introduced, php.ini-recommended was interestingly referred to as 'php.ini-optimized'. Over the years, it has become fairly standard to regard php.ini-recommended as 'production settings'; things like ''display_errors=Off'' and ''log_errors=On'' have helped this perception along. From inception, ''allow_call_time_pass_reference'' was switched ''Off'' in php.ini-recommended but ''On'' in php.ini-dist and by default. For the last 8 years, therefore, the first anyone is likely to have known about their code being less than kosher is when it went live.
  
 Even in the current php.ini-recommended, the switch is attributed only to 'Code cleanliness'. The full entry in the heading about changed settings reads: Even in the current php.ini-recommended, the switch is attributed only to 'Code cleanliness'. The full entry in the heading about changed settings reads:
  
 +<code>
 ; - allow_call_time_pass_reference = Off     [Code cleanliness] ; - allow_call_time_pass_reference = Off     [Code cleanliness]
 ;     It's not possible to decide to force a variable to be passed by reference ;     It's not possible to decide to force a variable to be passed by reference
 ;     when calling a function.  The PHP 4 [sic] style to do this is by making the ;     when calling a function.  The PHP 4 [sic] style to do this is by making the
 ;     function require the relevant argument by reference. ;     function require the relevant argument by reference.
 +</code>
 +
 +In fact, allowing values to be passed by reference is the default behaviour in PHP, and has been from PHP 4.0 beta right up to PHP 5.3.
  
-In fact, allowing return values by reference is the default behaviour in PHP, and has been from PHP 4.0 beta right up to PHP 5.3. 
  
 ===== Reality Check ===== ===== Reality Check =====
  
-In some circumstances, on some platforms, returning values by reference can actually speed up your code. In most cases, though - and for all when it comes to large arrays - it carries a performance penalty. If you make use of by-ref for performance reasons on a given platform, that optimization will not be portable.+In some circumstances, on some platforms, passing values by reference can actually speed up your code. In most cases, though - and for all when it comes to large arrays - it carries a performance penalty. If you make use of by-ref for performance reasons on a given platform, that optimization will not be portable. 
  
 ===== Future ===== ===== Future =====
  
-The directive is completely gone from CVS HEAD [3]. The effect of this originally was that a new-to-many ''E_STRICT'' would be thrown when values are returned by reference. However, it's been moved to ''E_DEPRECATED'' recently. In either case, it will no longer be possible to turn the warning off.+The directive is completely gone from CVS HEAD [3]. The effect of this originally was that a new-to-many ''E_STRICT'' would be thrown when values are passed by reference. However, it's been moved to ''E_DEPRECATED'' recently. In either case, it will no longer be possible to turn the warning off.
  
 ===== Proposal ===== ===== Proposal =====
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   - [3] [[http://cvs.php.net/viewvc.cgi/php-src/main/main.c?r1=1.676&r2=1.677]]   - [3] [[http://cvs.php.net/viewvc.cgi/php-src/main/main.c?r1=1.676&r2=1.677]]
  
- +==== Comments ==== 
 +currently allow_call_time_pass_reference is set to Off in both php.ini-production and php.ini-development for 5.3, and Call-time pass-by-reference was removed from 5.4, so this RFC is implemented/obsolete.
rfc/calltimebyref.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1