Why PHP allows violation of LSP in exceptions but not in regular classes (Declaration of.. should be compatible..)?

Question

Ok, check this out:

class MyParent
{
    public function myF($one, $two, $three)
    {
    }
}


class MyChild extends MyParent
{
    public function myF($one)
    {
    }
}

This throws the Strict standards: Declaration of MyChild::myF() should be compatible with MyParent::myF() - this is due to no overloading support in a weak-typed language, but the nice side effect is that it enforce LSP. No problem with that.

What puzzles me is that the following code doesn't throw the same error, even if \Exception's own __construct() takes three argument:

class MyChild extends \Exception
{
    public function __construct($first)
    {
    }
}

Why is that? why is the behavior for exception different? is this offically documented on the php.net site?

Constructors are different than other functions. Try adding a constructor to your `MyParent` class and add a different constructor to `MyChild`. It will work fine. What i mean to say is: It's not different for the exception class vs orther classes. — Meneer Venus, Aug 05 '15 at 08:40
http://stackoverflow.com/questions/15413829/why-does-php-allow-incompatible-constructors — georg, Aug 05 '15 at 08:41
@georg Now that Meneer pointed out the real issue, I flagged my own question as duplicate of the one you reported. That's it, thanks! — Dr. Gianluigi Zane Zanettini, Aug 05 '15 at 08:51

Why PHP allows violation of LSP in exceptions but not in regular classes (Declaration of.. should be compatible..)?

0 Answers0