如何在Delphi中将对象方法作为参数传递，然后调用它？

I fear this is probably a bit of a dummy question, but it has me pretty stumped.

我担心这可能是一个虚假的问题,但它让我非常难过。

I'm looking for the simplest way possible to pass a method of an object into a procedure, so that the procedure can call the object's method (e.g. after a timeout, or maybe in a different thread). So basically I want to:

我正在寻找将对象的方法传递给过程的最简单方法,以便过程可以调用对象的方法(例如,在超时之后,或者可能在不同的线程中)。所以基本上我想:

• Capture a reference to an object's method.

捕获对象方法的引用。

• Pass that reference to a procedure.

将该引用传递给过程。

• Using that reference, call the object's method from the procedure.

使用该引用,从过程中调用对象的方法。

I figure I could achieve the same effect using interfaces, but I thought there was another way, since this "procedure of object" type declaration exists.

我想我可以使用接口实现相同的效果,但我认为还有另一种方法,因为这种“对象过程”类型声明存在。

The following doesn't work, but might it help explain where I'm confused...?

以下不起作用,但它可能有助于解释我困惑的地方......?

interface 
  TCallbackMethod = procedure of object;

  TCallbackObject = class
    procedure CallbackMethodImpl;
    procedure SetupCallback;
  end;

implementation

procedure CallbackTheCallback(const callbackMethod: TCallbackMethod);
begin
  callbackMethod();
end;

procedure TCallbackObject.CallbackMethodImpl;
begin
  // Do whatever.
end;

procedure TCallbackObject.SetupCallback;
begin
  // following line doesn't compile - it fails with "E2036 Variable required"
  CallbackTheCallback(@self.CallbackMethodImpl);
end;

(Once the question is answered I'll remove the above code unless it aids the explanation somehow.)

(一旦问题得到解答,我将删除上述代码,除非它以某种方式帮助解释。)

2 个解决方案

#1

Just remove the Pointer stuff. Delphi will do it for you:

只需删除Pointer的东西。德尔福会为您做到:

procedure TCallbackObject.SetupCallback;
begin
  CallbackTheCallback(CallbackMethodImpl);
end;

#2

The reason you don't need the pointer syntax is that you've declared the method type as a procedure of object. The compiler will figure out from the "of object" statement how to handle passing the method off the callback proc.

您不需要指针语法的原因是您已将方法类型声明为对象的过程。编译器将从“of object”语句中弄清楚如何处理从回调proc传递方法。