CODEWITHSUNDEEP
phpoopfunctionoverriding
David Oliver
David Oliver

Reputation: 2502

Unable to override PHP class / function

I am unable to override a function in a child class at my local Ubuntu test LAMP server, but the very same code is resulting in the desired override when uploaded to a webserver.

Original class:

class HandsetDetection {
    function HandsetDetection() {
        //code I wish to replace
    }
}

My class:

class HandsetDetection_RespondHD extends HandsetDetection {
    function HandsetDetection() {
        //code I wish to use
    }
}

Constructors aren't involved.

The version of PHP in use on my local machine is PHP 5.3.3-1ubuntu9.5 with Suhosin-Patch (cli) (built: May 3 2011 00:48:48)

The version of PHP on the webserver where the override is successful is 5.2.17

Can you think why this may be?

Upvotes: 3

Views: 6471

Answers (2)

hakre
hakre

Reputation: 197624

Replace HandsetDetection() / prevent it from being called by giving the extending class a constructor method (Demo):

<?php

class A {

    function A() {
        echo "A() constructor\n";
    }
}

class B extends A {

    function __construct() {
        echo 'B() constructor', "\n";
    }

    function A() {
        echo "override\n";
    }

}

$x = new B();

Then things should turn out well. For an explanation about the background info, see @edorians answer with links to the manual etc.

Upvotes: 2

edorian
edorian

Reputation: 38961

I would assume it has something to do with the fact that the class has the same name as the method.

It's a php4 style constructor.

As long as the class is not in a namespace that is still an issue.

For backwards compatibility, if PHP 5 cannot find a __construct() function for a given class, it will search for the old-style constructor function, by the name of the class. Effectively, it means that the only case that would have compatibility issues is if the class had a method named __construct() which was used for different semantics.

Example:

<?php


class A {

    function A() {
        echo "construct";
    }
}

class B extends A {

    function A() {
        echo "override";
    }

}

$x = new B();

This will output "construct"

now calling

$x->A();

will output "override".

Upvotes: 11

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