Calling Static Method from Class B(which extends Class A) of Class A

Question

There was an interesting question in a practice test that I did not understand the answer to. What is the output of the following code:

Answer 1

Sometimes programmers are better at explaining things in code than in English!

The first thing going on here is the concept of overloading. When you instantiate Bar, it's getName() method overloads the method of the same name in Foo.

Overloading is a powerful and important part of OOD.

However, it is often useful to be able to call the version of a method that exists in the Parent class (Foo).

Here's an example:

class Dog
{
   public function getTag()
   {
      return "I'm a dog.";
   }
}

class Skip extends dog
{
   public function getTag()
   {
      return Dog::getTag() . " My name is Skip.";
      // I'm using Dog:: because it matches your example. However, you should use parent:: instead.
   }
}

$o = new Skip();
echo $o->getTag(); // Echo's: "I'm a dog. My name is Skip."

Clearly this is a very parochial example but it illustrates a point.

Your base class is the most general implementation of a Type. In this case, it's "Dog." You want to put information in this base class that is common to all instances of that Type. This prevents duplication in each of the Derived classes (like "Skip").

Your script is taking advantage of this feature, perhaps inadvertently.