object pascal - How to get a pointer to a method in a base class from a child class in Delphi? -

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here code example:

type   tmybaseclass = class   public     procedure someproc; virtual;   end;    tmychildclass = class(tmybaseclass)   public     procedure someproc; override;   end;  var   somedelegate: procedure of object;  procedure tmybaseclass.someproc; begin   showmessage('base proc'); end;  procedure tmychildclass.someproc; begin   showmessage('child proc');   // here want pointer tmybaseclass.someproc (not in class!):   somedelegate := someproc; end;  procedure tform1.button1click(sender: tobject); begin   tmychildclass.create   try     // there "child proc" message:     someproc;       free;   end;   // there want "base proc" message, "child proc" again   // (but destroyed anyway, how coud be?):   somedelegate; end;

the 1 way know is:

procedure tmychildclass.basesomeproc; begin   inherited someproc; end;   procedure tmychildclass.someproc; begin   showmessage('child proc');   somedelegate := basesomeproc; end;

the 2nd change someproc declaration override reintroduce:

 tmychildclass = class(tmybaseclass)  public     procedure someproc; reintroduce;  end;

and cast self tmybaseclass (do not use as cast):

 somedelegate := tmybaseclass(self).someproc;

also note code give access violation because call somedelegate on freed object.


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