2012/11/29 <michael.vancann...@wisa.be>: > > > On Thu, 29 Nov 2012, luiz americo pereira camara wrote: > > > Yes. I still do not see how your example shows this ? > > Your wizard knows it can observe. It attaches itself to the frame. > The code frame does not need to know the observing object ?
Yes, you are right in this wizard case the page owner would know it's an observer. [] >> It can crash since not necessarily owner (e.g. a simple TForm) will >> implements IFPObserver? > > > Who takes the decision to observe or not ? The TForm, I assume. > Somewhere the decision is made. In this location you will necessarily know > who will do the observing, and you will know it has IFPObserver. OK >> >> You would not be forced or induced to use an interface it would be >> optional. > > > Eh ? I would need to do a AttachObserver(MyObservingObject as IFPObserver) > everywhere where I want to observe, instead of > AttachObserver(MyObservingObject). > > That is hardly optional ? > It's the small cost i pointed elsewhere. In the other hand makes the code contract (what AttachObserver expects) clear in the declaration. Also improves compiler type check This is a trade off. I see your reason to hides the interface. >> >> BTW: did you read my comment about observer method not being public? >> By the currently implementation to attach a Observer to a TPersistent >> the programmer is _forced_ to use an interface contradicting what you >> said above. > > > I already fixed that. I also fixed the sender problem. In my cases I always > had (Sender=Self). > Thanks Did you read the TGUID (not necessary) part? >> I know what to expect when i see an IFPObserver property but not when >> i see an TObject (although i can guess by the name). > > > I am sorry, but I really still do not understand your problem with the > interface. > > Contrary to what it may look like, it is not so that I am dead set against > such a change. However, to me, your change presents a serious disadvantage. > Therefore I expect you at least to show to me that there is a substantial > need or benefit in this for all of us. > > Because till now I simply do not see the need or benefit... In the program that i mentioned in other message there's a use case for observer. I'll try to implement it and post the result here. Luiz _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
