PHP Migration Knowledge Base PHP 4 style class constructor is removed

PHPCompatibility Code

PHPCompatibility.FunctionNameRestrictions.RemovedPHP4StyleConstructors.Found

Recommendation

If you use PHPStorm, you can automatically fix this issue. Follow the Auto-Fix Inspection in PHPStorm guide.

If you don't use PHPStorm, you can follow the guide below to make those changes manually.

Before

class A extends B
{
    function A()
    {
        $this->B();
    }
}
class B
{
    function B()
    {
    }
}


$var = new A();

After

class A extends B
{
    function __construct()
    {
        B::__construct();
    }
}
class B
{
    function __construct()
    {
    }
}


$var = new A();

Explanation

Do not merely use parent::__construct, as that can overlook an edge case that was only possible with the PHP 4 style constructors. Consider the following code:

class A extends B
{
    function A()
    {
        $this->C();
    }
}
class B extends C
{
    function B()
    {
        throw new Exception('This should never be called');
    }
}
class C
{
    function C()
    {
    }
}

$var = new A();

If we were to replace $this->C() with merely parent::__construct, then we'd be executing the wrong constructor and alter the original logic. This is why we need to call the specific class' constructor using A::__construct. PHPStorm's replacement is therefore the correct one.