call a function before method call

Question

Design question / PHP: I have a class with methods. I would like to call to an external function anytime when any of the methods within the class is called. I would like to make it generic so anytime I add another method, the flow works with this method too.

Simplified example:

<?php

function foo()
{
    return true;
}

class ABC {
    public function a()
    {
        echo 'a';
    }
    public function b()
    {
        echo 'b';
    }
}

?>

I need to call to foo() before a() or b() anytime are called.

How can I achieve this?

Any necessary for that. It seems to be like a constructor in a class — Ranjith
– Ranjith, Commented Mar 2, 2015 at 10:08
Use the decorator pattern with hooks to the __call and __callStatic to intercept any method call and execute your function before doing the real call. — didierc
– didierc, Commented Mar 2, 2015 at 10:11
@didierc can you please paste a sudo code here as it is not understandable for many people beginners like me. — Raheel
– Raheel, Commented Mar 2, 2015 at 10:24
@RaheelKhan I have no doubt you'll be able to figure it out by yourself with a little bit of time. Anyway, my answer is posted. — didierc
– didierc, Commented Mar 2, 2015 at 10:26

Mark Baker · Accepted Answer · 2015-03-02 10:18:37Z

9

Protect your methods so they're not directly accessible from outside the class, then use the magic __call() method to control access to them, and execute them after calling your foo()

function foo()
{
    echo 'In pre-execute hook', PHP_EOL;
    return true;
}

class ABC {
    private function a()
    {
        echo 'a', PHP_EOL;
    }
    private function b($myarg)
    {
        echo $myarg, ' b', PHP_EOL;
    }

    public function __call($method, $args) {
        if(!method_exists($this, $method)) {
            throw new Exception("Method doesn't exist");
        }
        call_user_func('foo');
        call_user_func_array([$this, $method], $args);
    }
}

$test = new ABC();
$test->a();
$test->b('Hello');
$test->c();

answered Mar 2, 2015 at 10:18

Mark Baker

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1 Comment

kta Over a year ago

It does not work if ABC class is extended and ABC class uses parent class method. It gets to call_user_func_array and generates method not found an exception.

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