Abstraction (Delphi and C++ Cross Reference Guide)

Delphi for Win32 supports abstract class members using the abstract keyword. You can even instantiate instances of a class that contains abstract members. Then you override each abstract member in a descendant class with Override.

Delphi does not support setting an entire class as abstract. You can create an abstract class (a class with one or more abstract methods), but there is no way to tell the compiler to not allow the instantiation of the abstract class.

Delphi does not support abstract member properties directly. To implement an abstract properity, make use of abstract methods. That is, you can read a GetPropertyX abstract function and write to a SetPropertyX abstract procedure. In effect, creating  an abstract property.

TCyborg = class(TObject)
public
  procedure Speak(pMessage: String); virtual; abstract;
  procedure Walk; virtual; abstract;
end;

TSeries600 = class(TCyborg)
public
  procedure Speak(pMessage: String); override;
  procedure Walk; override;
end;

 Delphi Abstraction (abstract, override)

AbstractMemberFunction is a pure virtual function makes this class Abstract class indicated by the "=0"and NonAbstractMemberFunction1 is a virtual function.

class AbstractClass {
public:
  virtual void AbstractMemberFunction() = 0;

  virtual void NonAbstractMemberFunction1();

};

 C++ Abstraction (=0 in a virtual method)