PHP array_merge or array_unique and closures

Question

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 ?

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
– Mark Baker, Commented Mar 28, 2013 at 16:26
Thank you @MarkBaker make an answer and you'll get the kudos :) Is that the right syntax btw ? — Ælex
– Ælex, Commented Mar 28, 2013 at 16:27
@Alex .. what would be the expected output since you want to merge not filter ... ? — Baba
– Baba, Commented Mar 28, 2013 at 16:27
@Baba in this case an array of merged arrays of objects without duplicates I would hope. — Ælex
– Ælex, Commented Mar 28, 2013 at 16:29

Anyone · Accepted Answer · 2013-03-28 16:31:56Z

2

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 ;)

answered Mar 28, 2013 at 16:31

Anyone

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2 Comments

Ælex Over a year ago

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

Anyone Over a year ago

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.

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