Anonymous function with dynamic number of arguments/parameters

Question

So, some time ago I build a parser for jQuery Query Builder plugin, which parses the formula into PHP code that returns some calculation based on added parameters, it could range from return $a + $b; to something like

if($a == 'some_value' || $c == 'other_value') {
    return $something;
} else if($b == 'something' && $d == 'anything') {
    return $something_else;
} else {
    return $anything;
}

and it could be even more complex. The thing is that it creates this as a string, which I then passed to another function which returns a dynamic function created with create_function, but that constructor in PHP is deprecated as of version 7.2.0.

My problem now is that I need to be able to create anonymous function with dynamic number of parameters, and those parameters need to have dynamic variable names. Here is my previous code

protected function createFunction($formula, &$data)
{
    $args = '';

    foreach($data as $key => $value) {
        $args .= '$' . $key . ', ';
    }

    return create_function(substr($args, 0, strlen($args) - 2), $formula);
}

As you can see, the $formula is that dynamic PHP code I wrote above, and $data is an associative array (usually a row from database). Any ideas?

Edit: Forgot to mention, the formula itself is not the problem, as I can just use eval() function for that (I'm not concerned with security here so it's ok), it's just that I'm not sure how to add dynamic number of parameters with dynamic variable names.

hassan · Accepted Answer · 2018-08-09 09:14:05Z

1

You may go with Anonymous functions with this.

I had used eval in this case due to your comment :

Edit: Forgot to mention, the formula itself is not the problem, as I can just use eval() function for that (I'm not concerned with security here so it's ok)

class Foo
{
    public function createFunction($formula, $args)
    {
        $func = function ($args) use ($formula) {
            foreach ($args as $key => $val) {
                $$key = $val;
            }
            return eval($formula);
        };
        return $func($args);
    }
}

$foo = new Foo;

$foo->createFunction('echo $a + $b;', ['a' => 1, 'b' => 2]);

a live sample for your code https://3v4l.org/HrMKN

edited Aug 9, 2018 at 9:14

answered Aug 9, 2018 at 8:55

hassan

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3 Comments

AwesomeGuy Over a year ago

This looks good, I will test it a bit later and then probably mark this one as the right answer. Thanks

hassan Over a year ago

let me know if there are any issues

AwesomeGuy Over a year ago

Ok, I've checked this, and it's good except one line (actually, all is good, just for my case I need to change it), return $func($args); needs to return the function, not the result of it, so it should be return $func; But everything else is perfect, thanks again. :)

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