Re: [DUG]: Events in DLLS

[Phil Middlemiss]

rather than supporting events, support callbacks. Almost the same thing, but slightly different way of going about it.   For example, in your DLL you can have an Setup routine that is passed a record with the addresses of the routines that you want to handle an event. The DLL can store those addresses so that when the event should take place, it's actually calling a procedure.   eg (with just a single event):   unit ComonUnit ... Type   TMyProc = procedure(SomeParameter : SomeType....); ... end; _______________________ unit MyDLL   uses CommonUnit ... var   dllcallback : Pointer;   procedure Setup(aCallBack : Pointer); begin   dllcallback := aCallBack; end;   procedure SomeProc; begin   ...   if Assigned(dllcallback) then TMyProc(dllcallback)(parameters...); end;   exports    Setup ..... ...   end. __________________ unit MyApp   interface uses CommonUnit; procedure Setup(blah blah); stdcall; external 'MyDLL'; ... impementation .... procedure MyRealProc(same parameter types as TMyProc); begin ... end;   procedure SomeKindOfSetupProcedure; begin   Setup(MyRealProc);    //or maybe Setup(@MyProc) can't remember which end;   ____________________ This is more or less it. You'll have to shake out the bugs.   Phil. ----- Original Message ----- From: Jeremy Coulter To: Multiple recipients of list delphi Sent: Sunday, February 11, 2001 4:21 PM Subject: [DUG]: Events in DLLS HI all....another DLL question.   The DLL I am using can raise events when something happens, i.e    function incomingevent: Smallint; stdcall; external 'mydll';   how do I code for this ? do I do something like,   property OnEventHappeing : Integer read incomingevent   ??   Cheers, Jeremy Coulter