rfc:argument_unpacking

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rfc:argument_unpacking [2013/08/31 09:32] – change exception -> e_strict nikicrfc:argument_unpacking [2014/07/31 20:32] – fix now invalid code nikic
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   * Date: 2013-08-30   * Date: 2013-08-30
   * Author: Nikita Popov <nikic@php.net>   * Author: Nikita Popov <nikic@php.net>
-  * Status: Under Discussion +  * Status: Implemented (in PHP 5.6) 
-  * Proposed for: PHP 5.6 +  * Patch: https://github.com/php/php-src/pull/477
-  * Patch: https://github.com/nikic/php-src/compare/variadics...splat+
   * Mailing list discussion: http://markmail.org/message/dxae5ybjldg6pftp   * Mailing list discussion: http://markmail.org/message/dxae5ybjldg6pftp
  
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 </code> </code>
  
-It's possible to use ''%%...%%'' multiple times in a call and it is possible to mix it with normal arguments:+It's possible to use ''%%...%%'' multiple times in a call and it is possible to use normal arguments before argument unpacking:
  
 <code php> <code php>
-test(1, 2, ...[3, 4], 5, 6, ...[7, 8]); // [1, 2, 3, 4, 5, 6, 78]+$args1 = [1, 2, 3]; 
 +$args2 = [4, 5, 6]; 
 +test(...$args1, ...$args2); // [1, 2, 3, 4, 5, 6
 +test(1, 2, 3, ...$args2);   // [1, 2, 3, 4, 5, 6
 +</code> 
 + 
 +Howeverit is not possible to use normal arguments after argument unpacking was used. Both of the following are invalid: 
 + 
 +<code php> 
 +test(...$args14, 5, 6); 
 +test(...$args1, 4, 5, 6, ...$args2);
 </code> </code>
  
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 <code php> <code php>
-var_dump(1, 2, ...null, 3, 4);+var_dump(1, 2, ...null, ...[3, 4]);
 // Warning: Only arrays and Traversables can be unpacked // Warning: Only arrays and Traversables can be unpacked
 // int(1) int(2) int(3) int(4) // int(1) int(2) int(3) int(4)
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 </code> </code>
  
-By-reference passing will not work if the unpacked entity is a Traversable. Instead an ''E_STRICT'' level error is thrown and the argument is passed by-value instead:+By-reference passing will not work if the unpacked entity is a Traversable. Instead an ''E_WARNING'' level error is thrown and the argument is passed by-value instead:
  
 <code php> <code php>
 test(...new ArrayIterator([1, 2, 3, 4, 5])); test(...new ArrayIterator([1, 2, 3, 4, 5]));
-// Strict standards: Cannot pass by-reference argument 3 of test() by unpacking a Traversable, passing by-value instead+// Warning: Cannot pass by-reference argument 3 of test() by unpacking a Traversable, passing by-value instead
 </code> </code>
  
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   * It's not possible to determine the number of elements in a Traversable ahead of time. As such we can not know whether unpacking the Traversable will or will not hit a by-reference argument.   * It's not possible to determine the number of elements in a Traversable ahead of time. As such we can not know whether unpacking the Traversable will or will not hit a by-reference argument.
   * It's not possible to determine if a Traversable has support for by-reference iteration or if it will trigger an error if this is requested.   * It's not possible to determine if a Traversable has support for by-reference iteration or if it will trigger an error if this is requested.
 +
 +==== String keys ====
 +
 +In order to ensure forward-compatibility with [[rfc:named_params|named arguments]] the unpacking operator does not support string keys. If a string key is encountered during unpacking a recoverable error is thrown. If the error is ignored using a custom error handler, no further arguments will be unpacked but the call still happens.
  
 ===== Backward Compatibility ===== ===== Backward Compatibility =====
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 ===== Patch ===== ===== Patch =====
  
-The diff can be found here: https://github.com/nikic/php-src/compare/variadics...splat+The patch for this features is available as a PR: https://github.com/php/php-src/pull/477 
 + 
 +===== Vote ===== 
 + 
 +As this is a language change a two third majority is required. 
 + 
 +Voting started 2013-12-21 and ended 2014-01-11.
  
-The patch is based off the variadics implementation, but can also be implemented without it.+<doodle title="Implement argument unpacking in PHP 5.6?" auth="nikic" voteType="single" closed="true"> 
 +   * Yes 
 +   * No 
 +</doodle>
  
 ===== Support in other languages ===== ===== Support in other languages =====
rfc/argument_unpacking.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1