How to make an Abstract Class inherit from another Abstract Class in Python?

Have a look at abc module. For 2.7: link. For 3.6: link Simple example for you: from abc import ABC, abstractmethod class A(ABC): def __init__(self, value): self.value = value super().__init__() @abstractmethod def do_something(self): pass class B(A): @abstractmethod def do_something_else(self): pass class C(B): def do_something(self): pass def do_something_else(self): pass

c# Abstract Class implementing an Interface

Ad 1: The additional abstract base class allows you to evolve the interface without breaking the implementation. Supposed there was no abstract base class, and you’d extend the interface, let’s say by adding a new method. Then your implementation was broken, because your class does not implement the interface any longer. Using an additional abstract … Read more

Java: static abstract (again) – best practice how to work around

To restate the problem: you want your per-file-type classes to have statically available information on the type (e.g., name and description). We can easily get part-way there: create a separate class for your type info, and have a static instance of this (appropriately instantiated) in each per-file-type class. package myFileAPI; public class TypeInfo { public … Read more

Scala client composition with Traits vs implementing an abstract class

I don’t know what your source is for the claim that you should prefer traits over abstract classes in Scala, but there are several reasons not to: Traits complicate Java compatibility. If you have a trait with a companion object, calling methods on the companion object from Java requires bizarre MyType$.MODULE$.myMethod syntax. This isn’t the … Read more

Abstract methods in Java

Abstract methods means there is no default implementation for it and an implementing class will provide the details. Essentially, you would have abstract class AbstractObject { public abstract void method(); } class ImplementingObject extends AbstractObject { public void method() { doSomething(); } } So, it’s exactly as the error states: your abstract method can not … Read more

Overriding an abstract property with a derived return type in c#

This isn’t really a good way to structure things. Do one of the following 1) Just don’t change the return type, and override it normally in the subclass. In DerivedHandler you can return an instance of DerivedRequest using the base class signature of Request. Any client code using this can choose to cast it to … Read more

Is there a way to make sure classes implementing an Interface implement static methods?

You cannot require classes to implement particular static methods through an interface. It just makes no sense in Java terms. Interfaces force the presence of particular non-static methods in the classes that implement the interface; that’s what they do. The easiest way is definitely to have some sort of factory class that produces instances of … Read more