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| rfc:combined-comparison-operator [2015/01/22 23:57] – ajf | rfc:combined-comparison-operator [2016/05/16 22:10] – Remove infamously incorrect comment ajf |
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| * Version: 0.2.1 | * Version: 0.2.1 |
| * Date: 2014-02-12 (original), 2015-01-19 (v0.2) | * Date: 2014-02-12 (original), 2015-01-19 (v0.2) |
| * Authors: Davey Shafik <davey@php.net>, Andrea Faulds <ajf@ajf.me> | * Authors: Davey Shafik <davey@php.net>, Andrea Faulds <ajf@ajf.me>, Stas Malyshev <stas@php.net> |
| * Status: Under Discussion | * Status: Accepted |
| * First Published at: http://wiki.php.net/rfc/combined-comparison-operator | * First Published at: http://wiki.php.net/rfc/combined-comparison-operator |
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| Add a new operator ''(expr) %%<=>%% (expr)'', it returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater. It uses exactly the same comparison rules as used by our existing comparison operators: ''%%<, <=, ==, >=%%'' and ''>''. (See the manual for [[http://php.net/manual/en/language.operators.comparison.php|details]]) | Add a new operator ''(expr) %%<=>%% (expr)'', it returns 0 if both operands are equal, 1 if the left is greater, and -1 if the right is greater. It uses exactly the same comparison rules as used by our existing comparison operators: ''%%<, <=, ==, >=%%'' and ''>''. (See the manual for [[http://php.net/manual/en/language.operators.comparison.php|details]]) |
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| This operator (''%%<=>%%'') is often called the spaceship operator, and works on all standard PHP values. It exists in other languages: Perl, Groovy and Ruby. | This [[https://en.wikipedia.org/wiki/Three-way_comparison|"three-way comparison operator"]], also known as the "spaceship operator" (a common name in other languages), works on all standard PHP values. It exists in other languages: [[http://perldoc.perl.org/perlop.html#Equality-Operators|Perl]], [[http://ruby-doc.org/core-1.9.3/Comparable.html|Ruby]], and Groovy. |
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| For [[http://perldoc.perl.org/perlop.html#Operator-Precedence-and-Associativity|consistency with Perl]], it has the same precedence as ''=='' and ''!=''. | For [[http://perldoc.perl.org/perlop.html#Operator-Precedence-and-Associativity|consistency with Perl]], it has the same precedence as ''=='' and ''!=''. |
| It is implemented by using the result of the existing internal ''compare_function'' that underlies the other comparison operators. The existing comparison operators could be considered mere shorthands for ''%%<=>%%'': | It is implemented by using the result of the existing internal ''compare_function'' that underlies the other comparison operators. The existing comparison operators could be considered mere shorthands for ''%%<=>%%'': |
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| * ''$a < $b'' is equivalent to ''%%($a <=> $b) === -1%%'' | ^ operator ^ ''%%<=>%%'' equivalent ^ |
| * ''$a > $b'' is equivalent to ''%%($a <=> $b) === 1%%'' | | ''$a < $b'' | ''%%($a <=> $b) === -1%%'' | |
| * ''$a == $b'' is equivalent to ''%%($a <=> $b) === 0%%'' | | ''%%$a <= $b%%'' | ''%%($a <=> $b) === -1 || ($a <=> $b) === 0%%'' | |
| * (and so on) | | ''$a == $b'' | ''%%($a <=> $b) === 0%%'' | |
| | | ''$a != $b'' | ''%%($a <=> $b) !== 0%%'' | |
| | | ''%%$a >= $b%%'' | ''%%($a <=> $b) === 1 || ($a <=> $b) === 0%%'' | |
| | | ''$a > $b'' | ''%%($a <=> $b) === 1%%'' | |
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| Here are some examples of its behaviour: | Here are some examples of its behaviour: |
| echo $a <=> $b; // 1 | echo $a <=> $b; // 1 |
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| // only values are compared | |
| $a = (object) ["a" => "b"]; | $a = (object) ["a" => "b"]; |
| $b = (object) ["b" => "b"]; | $b = (object) ["b" => "b"]; |
| ===== Unaffected PHP Functionality ===== | ===== Unaffected PHP Functionality ===== |
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| All existing comparison operators, particularly ''%%<=%%'' are unaffected by this addition. | All existing comparison operators are unaffected by this addition. |
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| ===== Future Scope ===== | ===== Future Scope ===== |
| None. | None. |
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| ===== Proposed Voting Choices ===== | ===== Vote ===== |
| | |
| | Voting started on 2015-02-02 and will to end on 2015-02-16. As this adds to the PHP language (and hence affects the PHP language specification) a 2/3 majority is required for acceptance. It is a Yes/No vote to accepting the RFC and merging the patch. |
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| | <doodle title="Accept the Combined Comparison (Spaceship) Operator RFC and merge patch into master?" auth="stas" voteType="single" closed="true"> |
| | * Yes |
| | * No |
| | </doodle> |
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| A two third majority is required for acceptance, as it is a language change. It will be a Yes/No vote to accepting the RFC and merging. | |
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| ===== Patches and Tests ===== | ===== Patches and Tests ===== |