What is the benefit and in what cases use closures in PHP?

Question

Ex.: Why use a closure for this function:

We could do the same thing without a closure, but why use this class?

public function getTotal($tax)
{
    $total = 0.00;

    $callback =
        function ($quantity, $product) use ($tax, &$total)
        {
            $pricePerItem = constant(__CLASS__ . "::PRICE_" .
                strtoupper($product));
            $total += ($pricePerItem * $quantity) * ($tax + 1.0);
        };

    array_walk($this->products, $callback);
    return round($total, 2);
}

http://www.php.net/manual/en/class.closure.php

Answer 1

Marcelo,

In my experience with javascript and c# I could say that Clousure is used to explore aspects of scope and context.

In javascript and other languages that allow us to be event-oriented (like c#) we use a lot to access variables from other scopes. It’s a way for you to apply some Patterns design like Strategy and dependency inversion.. roughly speaking: calling a function, within another function, that reuses values from the first function, in a reduced context...

Most people do not understand event-oriented programming and therefore unjustly complain of javascript.

However, I recommend you take a look here: http://howtonode.org/why-use-closure

The examples are in javascript but the concept transcends languages.