PHP 7: Immediately Invoked Function Expressions

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PHP7 will continue to borrow some of the beloved JavaScript features and will support Immediately Invoked Function Expressions (IIFEs):

<?php

echo (function() {
    return 42;
})();
Output for php7@20140901 - 20141101:
42

Since we can already return functions from inside other functions, Currying Partial Application is also possible in combination with the IIFE implementation:

<?php

$foo = (function() {
    return function($a) {
        return $a + 42;
    };
})();

echo $foo(10);
Output for php7@20140901 - 20141101:
52

Note that when accessing an outer variable from within a function, one – unlike in JavaScript which has closures – needs to use the use keyword to make that variable accessible:

<?php

$foo = (function($a) {
    return function($b) use ($a) {
        return $a + $b;
    };
})(42);
echo $foo(10);
Output for php7@20140901 - 20141101:
52

/me is excited!

PHP7 IIFE Demo →
PHP7 Currying Demo →
PHP7 Currying Redux Demo →

Published by Bramus!

Bramus is a frontend web developer from Belgium, working as a Chrome Developer Relations Engineer at Google. From the moment he discovered view-source at the age of 14 (way back in 1997), he fell in love with the web and has been tinkering with it ever since (more …)

Unless noted otherwise, the contents of this post are licensed under the Creative Commons Attribution 4.0 License and code samples are licensed under the MIT License

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5 Comments

  1. I was just trying to do this in PHP today and was a little sad finding out that you can’t. But I’m very glad to see these changes coming! (soon?)

      1. Bro good job. I can execute logical expression with your IIFE –

        $a = [‘no’,’no’, ‘yes’, ‘np’, 787];
        if (in_array(‘yes’, $a)) echo “hello”;

        OR WITH YOUR IIFE –

        in_array(‘yes’, $a) && call_user_func(function() {
        echo “hello”;
        });

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