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Can I merge an array, or remove duplicates from an array in PHP >=5.4 using a closure, in the same fashion as it can be done in Objective C using a block, or in C++ using a lambda ?

  • Is it possible to use a predicate/closure/block/lambda as a parameter to such functions.

I.e:

$a = array('blah','bleh');
$b = array('blih, 'bloh');
$arr = array_merge( function() use (&$a,&$b) { return $a == $b ? true : false; } );

(Above example is oversimplified, I want to do this for Objects).

  • Can it be done inline or should I always define the closure as an $var ?
  • Is there a performance gain, or does it run the same ?
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1  
You'd probably use array_filter with a closure to eliminate duplicates; and yes, it is perfectly possible with an array of objects –  Mark Baker Mar 28 '13 at 16:26
    
Thank you @MarkBaker make an answer and you'll get the kudos :) Is that the right syntax btw ? –  Alex Mar 28 '13 at 16:27
    
@Alex .. what would be the expected output since you want to merge not filter ... ? –  Baba Mar 28 '13 at 16:27
    
@Baba in this case an array of merged arrays of objects without duplicates I would hope. –  Alex Mar 28 '13 at 16:29
    
So, array_unique(array_merge())? –  deceze Mar 28 '13 at 16:32
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1 Answer

up vote 1 down vote accepted

You can probably use array_filter() for this. My guess is that you need to filter 1 array as parameter and add the second array as use(). When the current value is not in the array passed in use(), you can add it. http://php.net/manual/en/function.array-filter.php

This only if you need to check based on a value inside the object ofc as $a == $b can be tricky with objects ;)

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Huh, that is very interesting. Thank you for linking this, I see they already used a function callback, I assume I could just pass a closure to this as well? Kudos for the cleanest solution –  Alex Mar 29 '13 at 14:03
1  
Closures and callables are a bit off in PHP. Here's some more information regarding callables. php.net/manual/en/language.types.callable.php As of 5.4 the type Callable has been added and as of 5.3 closures have been added. Before that you had specific functions which allowed a 'function_name' or array($my_obj, 'method_name') to be faked into a 'callable' parameter. –  Anyone Mar 29 '13 at 14:16
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