《GOF设计模式》—桥接（BRIDGE）—Delphi源码示例：仅有一个Implementor

示例：仅有一个Implementor
说明：
在仅有一个实现的时候，没有必要创建一个抽象的Implementor类。这是Bridge模式的退化情况；在Abstraction与Implementor之间有一种一对一的关系。尽管如此，当你希望改变一个类的实现不会影响已有的客户程序时，模式的分离机制还是非常有用的—也就是说，不必重新编译它们，仅需重新连接即可（例如，Abstraction在主程序实现，Implementor在DLL中实现）。

代码：

unit uBridge1;

interface

uses
Dialogs;

type
TImplementor = class;

{抽象类}
TAbstraction = class
private
FImp: TImplementor;
public
constructor Create(AImplementor: TImplementor);
//---
procedure Operation; virtual;
end;
TRefinedAbstraction = class(TAbstraction)
public
procedure Operation; override;
end;

{实现类}
TImplementor = class
procedure OperationImp;
end;

implementation

constructor TAbstraction.Create(AImplementor: TImplementor);
begin
FImp := AImplementor;
end;

procedure TAbstraction.Operation;
begin
FImp.OperationImp;
end;

procedure TImplementor.OperationImp;
begin
ShowMessage('Implementor');
end;

procedure TRefinedAbstraction.Operation;
begin
inherited;
//---
ShowMessage('Refined');
end;

end.

procedure TForm1.Button1Click(Sender: TObject);
var
AImplementor: TImplementor;
AAbstraction: TAbstraction;
begin
AImplementor := TImplementor.Create;
AAbstraction := TRefinedAbstraction.Create(AImplementor);
try
AAbstraction.Operation;
finally
AAbstraction.Free;
AImplementor.Free;
end;
end;