php anonymous functions in php 5

Question

I've been using callback function like this:

private function make_f($arg1, $arg2)
{
    $callback =
        function ($my_var) use ($arg1, $arg2)
        {
            return $my_var  * $arg1 * arg2;
        };
    return $callback;
}

It supports by PHP 5.3.0 but my hosting provider has PHP 5.2.6 so it doesn't work. Is there any way to repair this somehow?

@Dan Lee: $my_var will be passed as a parameter when the closure is called in the future. — webbiedave
– webbiedave, Commented Apr 17, 2012 at 23:05
PHP 5.0 is seriously ancient (it was released in 2005). You should probably consider a better hosting provider. — user149341
– user149341, Commented Apr 17, 2012 at 23:07

Ry- · Accepted Answer · 2012-04-17 23:10:27Z

4

That really depends on what $arg is. For any possible value of $arg, I can only come up with something like this:

public static $arguments = array();

private function make_f($arg)
{
    $variable_name = uniqid();

    ThisClass::$arguments[$variable_name] = $arg; // Replace ThisClass with the name of the actual class

    $callback = create_function('$my_var', 'return $my_var * ThisClass::$arguments[\'' . $variable_name . '\'];');

    return $callback;
}

Here's a demo.

edited Apr 17, 2012 at 23:10

answered Apr 17, 2012 at 23:04

Ry-♦

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2 Comments

Ry- Over a year ago

@webbiedave: How so? I'm pretty sure uniqid doesn't depend solely on the clock. Or do you mean something else?

webbiedave Over a year ago

I deleted my comment after re-reading :) This solution works and is pretty much the only way to achieve this < 5.3. @Yekver: Just keep in mind that create_function will add a new function in memory everytime make_f is called (it won't reuse). So, if you're calling 100's of times in a loop, memory will be eaten. Other than that, this answers the OP's question perfectly. + 1

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