[fpc-pascal]Passing Methods as Callback Procedures?

Judison jueca at brturbo.com
Mon Dec 16 19:38:12 CET 2002


On Sun, 15 Dec 2002 15:32:43 +0000
Jon David Sawyer <badquanta6384 at comcast.net> wrote:

> Ok,  I've got some code that looks like this:
> fCollection.ForEach(@Self.DoEach);

fCollection is a TCollection?
My TCollection does not have ForEach ;) (1.1 CVS 2002/12/13)

> Now when DoEach() is called its Self and the Self above
> are not the same...
> Is this supposed to happen?

It depends on ForEach declaration.

if it is something like this:

procedure ForEach(CallBack: procedure(x: integer));

I really don't know if FPC will compile it, as your DoEach is a method (procedure of object)
I hope you's ForEach declaration is something like:

procedure ForEach(CallBack: procedure(x:integer) of object);

Normally you have a Type
  TForEachCallBackProc = procedure(x: integer) of object;

a type "procedure" is just a pointer to de procedure, a "procedure of object" is (I Think) a record, with a pointer to a procedure and other to the context (Self).... (I don't know exactly how OO works in FPC)

I hope this can help you
Your Friend,

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