CODEWITHSUNDEEP
delphi
Realbitt
Realbitt

Reputation: 408

delphi reference event object by variable TObject

i have component with function getsomedata (key:string;listener:Tlistener)

which listener declared like event as follow :

Tlistener = procedure (name,age,sex:string) of object ;

but in my component listener manager when i add the new listener takes listener parameter as TObject class like .

ListenerManager.addListener(key:string;Listener:TObject);

when i complile the code i got error message

Not enough actual parameters

because Event Object (TListener) and ListenerManager Parameter (TObject).

sample of full function code .

procedure getsomedata (key:string;listener:Tlistener) ; 
begin

ListenerManager.addListener(key,listener); //error Here >>> addListener input parameters (key:string;Listener:TObject);

end;

how can i resolve it ?

Upvotes: 0

Views: 726

Answers (1)

David Heffernan
David Heffernan

Reputation: 612784

In this code:

procedure getsomedata (key:string;listener:Tlistener) ; 
begin
  ListenerManager.addListener(key,listener);
end;

You are attempting to pass a variable of type TListener to the second parameter of addListener. That parameter is typed as being TObject.

Now, TListener is typed as being 

procedure(name,age,sex:string) of object;

A variable of procedural type cannot be passed to a parameter of type TObject.

It's rather difficult to know exactly what the correct code would look like because the question doesn't contain enough background information. Perhaps addListener should receive a TListener rather than a TObject. But that's just a guess. If you want more complete advice, then you will need to add sufficient detail to the question.

You state in a comment that:

I can not change the parameter type TObject to TListener.

In that case you are stuck. It's simply not possible to cast a TListener to a TObject. Now, you could implement a class that had a single field of type TListener, and pass that. But I doubt very much that's really the right solution.

Upvotes: 1

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