如何在VCL类中使用接口-第2部分 [英] How to use Interface with VCL Classes - Part 2

问题描述

继续我之前有关将接口与VCL一起使用的调查。

continue with my previous investigation regarding the use of Interface with VCL.

如何使用2个或更多类来实现相同的方法？

< a href = https://stackoverflow.com/questions/8805768/how-to-use-interface-with-vcl-classes>如何在VCL类中使用接口？

我想举一个代码示例来演示两者在哪里以及如何一起工作。
或两者的经典收益/用法是什么？

I would like to have a code example to demonstrate where and how the two work together. Or what is the classic benefit/usage of the two:

ISomething = interface
['{EFE0308B-A85D-4DF3-889C-40FBC8FE84D0}']
...
end;

TSomeThing = class(TSomeVCLObject, ISomething)
...
end;

推荐答案

假设您有 TSomeThing 和 TSomeThingElse 类，但是它们没有共同的祖先类。照原样，您将无法将它们传递给相同的函数，也无法对其调用通用方法。通过将共享接口添加到两个类，您可以同时执行这两个操作，例如：

Imagine you have TSomeThing and TSomeThingElse classes, but they do not have a common ancestor class. As-is, you would not be able to pass them to the same function, or call a common method on them. By adding a shared interface to both classes, you can do both, eg:

type
  ISomething = interface 
  ['{EFE0308B-A85D-4DF3-889C-40FBC8FE84D0}'] 
  public
    procedure DoSomething;
  end; 

  TSomeThing = class(TSomeVCLObject, ISomething) 
    ... 
    procedure DoSomething;
  end; 

  TSomeThingElse = class(TSomeOtherVCLObject, ISomething) 
    ... 
    procedure DoSomething;
  end; 

procedure TSomeThing.DoSomething;
begin
  ...
end; 

procedure TSomeThingElse.DoSomething;
begin
  ...
end; 

procedure DoSomething(Intf: ISomething);
begin
  Intf.DoSomething;
end;

procedure Test;
var
  O1: TSomeThing;
  O2: TSomeThingElse;
  Intf: ISomething;
begin
  O1 := TSomeThing.Create(nil);
  O2 := TSomeThingElse.Create(nil);
  ...
  if Supports(O1, ISomething, Intf) then
  begin
    Intf.DoSomething;
    DoSomething(Intf);
  end;
  if Supports(O2, ISomething, Intf) then
  begin
    Intf.DoSomething;
    DoSomething(Intf);
  end;
  ...
  O1.Free;
  O2.Free;
end;

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