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Using external variables

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It is possible, inside a closure, to use an external variable with the special keyword use. For instance: 

<?php

$quantity = 1;

$calculator = function($number) use($quantity) {
    return $number + $quantity;
};

var_dump($calculator(2)); // Shows "3"

You can go further by creating “dynamic” closures. It is possible to create a function that returns a specific calculator, depending on the quantity you want to add. For example: 

<?php

function createCalculator($quantity) {
    return function($number) use($quantity) {
        return $number + $quantity;
    };
}

$calculator1 = createCalculator(1);
$calculator2 = createCalculator(2);

var_dump($calculator1(2)); // Shows "3"
var_dump($calculator2(2)); // Shows "4"
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Closur:
* Closure
* Basic usage of a closure
* Using external variables
* Basic closure binding
* Closure binding and scope
* Binding a closure for one call
* Use closures to implement observer pattern
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0 Getting started
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62 Installing on Linux / Unix
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100 Docker deployment
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106 PHP built-in server
107 How to break down an URL
108 PSR
109 Contributors