On Fri, 11 Aug 2006, Florian Klaempfl wrote:
Michael Van Canneyt wrote:
On Fri, 11 Aug 2006, Florian Klaempfl wrote:
Mattias Gaertner wrote:
Recently the behaviour of the 'protected' keyword has changed in fpc
2.1.1.
Now I wonder how can I fix the code, that depends on this.
Redesign :)
I have some base classes, that defines methods to let derived classes
interact.
These methods should not be accessed directly from the outside, so they
are protected. But this does not work any longer. Of course I can safely
typecast, but for aesthetic reasons it looks pretty bad coding style to
typecast a class to the wrong class. For example:
-- unit1 -------------------------
TMyClass = class
FFlag: boolean;
protected
procedure InternalSetFlag(b: boolean);
end;
-- unit2 -------------------------
TDescendantClass1 = class(TMyClass)
public
procedure CallProtectedMethod(AnObject: TMyClass);
end;
TDescendantClass2 = class(TMyClass)
end;
procedure TDescendantClass1.CallProtectedMethod(AnObject: TMyClass);
begin
InternalSetFlag(true); // allowed
AnObject.InternalSetFlag(true); // not allowed any longer
TDescendantClass1(AnObject).InternalSetFlag(true); // allowed and
works, but ugly
Shouldn't be allowed either imo.
Why not ? In a descendent class you 'know' the protected method.
But only of the current instance, no?
Well, nothing is said about this in the manuals; For me this is up to
discussion.
It seems normal to me that it is not just the current instance. You KNOW this
method is there, in a descendent, so it seems logical that you know that it
exists for another instance as well.
Personally, I think we should allow use of protected methods in a descendent,
also for other instances. In the above example:
AnObject.InternalSetFlag(true);
Should work. But since this is not Delphi compatible, I think this should be
in Objpas mode only.
Michael.
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