Polymorphism is a feature of object-oriented programming languages that allows different objects to respond to the same method call in different ways. In Delphi, polymorphism is implemented using virtual methods and overriding.
Here is an example of polymorphism in Delphi:
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type TShape = class public procedure Draw; virtual; abstract; end; TCircle = class(TShape) public procedure Draw; override; end; TRectangle = class(TShape) public procedure Draw; override; end; procedure TShape.Draw; begin // Default implementation for drawing a shape end; procedure TCircle.Draw; begin // Implementation for drawing a circle end; procedure TRectangle.Draw; begin // Implementation for drawing a rectangle end; var Shape: TShape; begin Shape := TCircle.Create; Shape.Draw; Shape.Free; Shape := TRectangle.Create; Shape.Draw; Shape.Free; end; |
In this example, the TShape class has an abstract Draw method that must be overridden by derived classes. The TCircle and TRectangle classes both override the Draw method to provide their own implementation for drawing the shape.
When the Draw method is called on a TShape object, the implementation from the most derived class is used. For example, when Shape.Draw is called on a TCircle object, the TCircle.Draw method is called. When Shape.Draw is called on a TRectangle object, the TRectangle.Draw method is called.
This allows different objects to respond to the same method call in different ways, depending on their specific type. Polymorphism is a powerful feature that can be used to create flexible and reusable code.
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