Generally speaking, the approach I use in this kind of situation is to have both an interface and an abstract class. The interfaces defines, well, the interface. The abstract class is merely a helper. You really can’t go wrong with this approach. Interfaces give you the flexibility to change implementation. Abstract classes give you boilerplate … Read more
Why is it necessary for an interface to be “declared” abstract? It’s not. public abstract interface Interface { \___.__/ | ‘—-> Neither this… public void interfacing(); public abstract boolean interfacing(boolean really); \___.__/ | ‘—-> nor this, are necessary. } Interfaces and their methods are implicitly abstract and adding that modifier makes no difference. Is there … Read more
An abstract function cannot have functionality. You’re basically saying, any child class MUST give their own version of this method, however it’s too general to even try to implement in the parent class. A virtual function, is basically saying look, here’s the functionality that may or may not be good enough for the child class. … Read more
It’s a long, sad story. When PHP 5.2 first introduced this warning, late static bindings weren’t yet in the language. In case you’re not familiar with late static bindings, note that code like this doesn’t work the way you might expect: <?php abstract class ParentClass { static function foo() { echo “I’m gonna do bar()”; … Read more
Use the abc module to create abstract classes. Use the abstractmethod decorator to declare a method abstract, and declare a class abstract using one of three ways, depending upon your Python version. In Python 3.4 and above, you can inherit from ABC. In earlier versions of Python, you need to specify your class’s metaclass as … Read more
From the same page you linked to: The interface Comparator is functional because although it declares two abstract methods, one of these—equals— has a signature corresponding to a public method in Object. Interfaces always declare abstract methods corresponding to the public methods of Object, but they usually do so implicitly. Whether implicitly or explicitly declared, … Read more
Here, i’m creating instance of my class No, you are not creating the instance of your abstract class here. Rather you are creating an instance of an anonymous subclass of your abstract class. And then you are invoking the method on your abstract class reference pointing to subclass object. This behaviour is clearly listed in … Read more