Question

Here is the simple php code

<?
abstract class A{
abstract public function a($x);
}
class B extends A{
public function a($x)
{
echo $x;
}
}

$q = new B;
$q->a(10);
?>

which gives:
PHP Fatal error: Cannot call abstract method A::a()

but changing the name of the function to something else than “a” works.

So what is really happening with the call to a(10) ?
I don’t see the logic here.

Answer 1

You got a pretty obvious problem. Since you don’t have a __construct() method, the abstract public function a(); is your constructor (php 4). Your fatal error fires when instantiating the B class, and not when calling method a() on the instance of B class.

If you change the name of your method a() in something else, all works as intended!

Example that works:

<?php
abstract class A
{
    abstract public function test($x);
}

class B extends A
{
    public function test($x)
    {
        echo $x;
    }
}

$q = new B();
$q->test(10);
?>