Unable to override PHP class / function

Question

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?

as edorian said, it is treated as PHP4 constructor, which can't be overridden this way. — Yousf, Jul 19 '11 at 12:04
"Constructors aren't involved." that's just wrong. Function `HandsetDetection::HandsetDetection` is the PHP 4 style constructor. See: Function Name = Class Name. — hakre, Jul 19 '11 at 12:23
@David Oliver: You need to give the extending class another method and things should turn out as you need them, see [my answer below](http://stackoverflow.com/questions/6746749/unable-to-override-php-class-function/6747084#6747084). — hakre, Jul 19 '11 at 12:27

edorian · Answer 1 · 2011-07-19T12:08:00.807

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".

score 2 · Accepted Answer · answered Jul 19 '11 at 12:26

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.

Unable to override PHP class / function

2 Answers2

Example: