CODEWITHSUNDEEP
phpcallback
Kamil
Kamil

Reputation: 13931

Callback in PHP - I need explanation

I found code similar to this:

function function_1($callback) 
{
    // not related code removed

    $callback($p);

}

How to call this function? What shall I put in $callback parameter?

Lets say, I want to use function called function_2($p).

Upvotes: 3

Views: 125

Answers (4)

bizzehdee
bizzehdee

Reputation: 21003

in older php versions, you would call it with 

function_1("function_2");

but in php 5.3, you could do

$function_2 = function($p) {
};

function_1($function_2);

For further reference, read Anonymous functions, Callbacks and call_user_func in the PHP manual.

Upvotes: 0

user2609094
user2609094

Reputation:

Here's the full explanation you want, straight from the php docs: Callbacks.

If you're on php 5.3+, you can pass a lambda (aka anonymous function):

<?php function_1(function ($p) { ... });

If you need support for previous versions of php, you need to define a regular function or instance method. Since the code you've shown is using $callback() instead of call_user_func($callback), you shouldn't need this.

<?php

// without a class
function function_2 ($p) { ... }
function_1('function_2');

// with a class
class A {
    public function function_2 ($p) { ... }

    public function doIt () {
        function_1(array($this, 'function_2'));
    }
}

Upvotes: 4

Vineet1982
Vineet1982

Reputation: 7918

Run it:

function function_2() 
{
    echo 'done';

}


function function_1($callback) 
{
    // not related code removed

    call_user_func($callback);

}

function_1("function_2");

Upvotes: 1

UnknownError1337
UnknownError1337

Reputation: 1222

function test($param)
{
}

function function_1($callback) 
{
    // not related code removed

    $callback($p);

}

function_1("test")

Upvotes: 0

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