rfc:in_operator

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rfc:in_operator [2015/02/19 23:56] – updated draft kelunikrfc:in_operator [2015/02/26 19:40] – kelunik
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 ====== PHP RFC: In Operator ====== ====== PHP RFC: In Operator ======
-  * Version: 0.2 +  * Version: 0.4 
-  * Date: 2015-02-20+  * Date: 2015-02-26
   * Authors: Niklas Keller <me@kelunik.com>, Bob Weinand <bobwei9@hotmail.com>   * Authors: Niklas Keller <me@kelunik.com>, Bob Weinand <bobwei9@hotmail.com>
-  * Status: Draft+  * Status: Under Discussion
   * First Published at: http://wiki.php.net/rfc/in_operator   * First Published at: http://wiki.php.net/rfc/in_operator
  
 ===== Introduction ===== ===== Introduction =====
-This RFC adds a new ''in'' operator which simplifies ''contains'' checks for strings and arrays. Currently, we have to use ''in_array($needle, $haystack, true)'' or ''strpos($haystack, $needle) !== false''. These functions have a inconsistent parameter order, so it's hard to remember which is the right one for each. The ''in'' operator makes these checks way more readable.+This RFC adds a new ''in'' operator which simplifies ''contains'' checks for strings and arrays. Currently, we have to use ''in_array($needle, $haystack, true)'' or ''strpos($haystack, $needle) !== false''. These functions have a inconsistent parameter order, so it's hard to remember which is the right one for each. The ''in'' operator makes these checks way more readable. Additionally, it also works for ''Traversable''.
  
 ===== Proposal ===== ===== Proposal =====
 Add a new operator ''(expr1) in (expr2)''. It checks whether ''expr2'' contains ''expr1''. Add a new operator ''(expr1) in (expr2)''. It checks whether ''expr2'' contains ''expr1''.
  
-It uses strict comparison (''==='') for array values and doesn't search recursively.+It uses strict comparison (''==='') for array values / instances of ''Traversable'' and doesn't search recursively.
  
 <code php> <code php>
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 $contains = "0e0" in ["0"]; // false, because of strict comparison $contains = "0e0" in ["0"]; // false, because of strict comparison
 $contains = 0 in ["0"]; // false, because of strict comparison $contains = 0 in ["0"]; // false, because of strict comparison
 +
 +$contains = ["foo"] in [["foo"], ["bar"]]; // true
 +$contains = ["foo"] in ["foo"]; // false
 </code> </code>
  
-If the first parameter is an array, it checks for every element whether it's contained in the ''$haystack'' or not. This is an advantage compared to ''in_array''. It doesn't check the values in ''$needle'' recursively, so it's still possible to check if an array contains another array, but makes checking multiple scalars easier:+''Traversable''s are only iterated until there's a match.
  
 <code php> <code php>
-$contains = ["foo", "bar"] in ["foo", "baz", "bar"]; // true +function gen () { 
-$contains = ["foo", "bar", "baz"] in ["foo", "bar"]; // false +    yield "foo"; 
-$contains = [["foo", "bar"]] in [["foo", "bar"], ["foo", "baz"]]; // true +    yield "bar"; 
-$contains = [["foo", "bar"]] in ["foo", "bar"]; // false+    // code below here wouldn't be executed if "bar" matches 
 +    // because it stops if there's a match. 
 +} 
 + 
 +$contains = "bar" in gen(); // true 
 +$contains = "baz" in gen(); // false
 </code> </code>
  
-For stings, it behaves exactly like ''strpos($haystack, $needle) !== false'':+If ''$haystack'' is a string or integer, it's a simple ''contains'' check, integers are converted to their string representation:
 <code php> <code php>
 $contains = "foo" in "foobar"; // true $contains = "foo" in "foobar"; // true
 $contains = "php" in "foobar"; // false $contains = "php" in "foobar"; // false
 +$contains = 0 in "0"; // true
 +$contains = 0 in 100; // true
 </code> </code>
  
-Objects are not supported, because we already have ''isset'' here.+**Note**: This is a difference compared to ''strpos(string, int)'' as it uses the string representation instead of searching for the the ordinal value of a character. 
 + 
 +Other values than ''string'', ''integer'', ''array'' or ''Traversable'' for ''$haystack'' will return false and emit a warning. 
 + 
 +If ''$haystack'' is of type string, only ''string'' and ''integer'' are allowed as type of ''$needle''. Other types will return false and emit a warning. 
 + 
 +==== Why strict? ==== 
 +It's strict because otherwise something like ''"foo" in [0]'' would pass. 
 + 
 +==== Precedence ==== 
 +It should have the same precedence as ''instanceof'', so it's possible to negate it: 
 + 
 +<code php> 
 +if (!$input in $validValues) { 
 +    // ... 
 +} 
 +</code>
  
 ===== Backward Incompatible Changes ===== ===== Backward Incompatible Changes =====
-New reserved keyword ''in''. This affects function, class and method names.+New reserved keyword ''in''. This affects function, constant, class and method names.
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
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 ===== Open Issues ===== ===== Open Issues =====
-Make sure there are no open issues when the vote starts!+None.
  
 ===== Future Scope ===== ===== Future Scope =====
-None.+There could be a syntax that allows to check for multiple values at once, e.g. 
 +<code php> 
 +$contains = ...["foo", "bar"] in ["foo", "baz", "bar"]; 
 +</code>
  
 ===== Proposed Voting Choices ===== ===== Proposed Voting Choices =====
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 ===== Patches and Tests ===== ===== Patches and Tests =====
-TBD +  * https://github.com/php/php-src/pull/1121
- +
-===== Implementation ===== +
-TBD+
  
 ===== Rejected Features ===== ===== Rejected Features =====
 Keep this updated with features that were discussed on the mail lists. Keep this updated with features that were discussed on the mail lists.
 +
 +===== Changelog =====
 +  * v0.4: Removed possibility to check multiple values using an array.
rfc/in_operator.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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