On Sun, 28 Oct 2012, bsquared wrote:
Hi all,
It has been some time since I have used FPC/Laz. I was looking for some
information on 'observer pattern' the other day, and I found this
article[1]. I notice that it is a bit old, and it makes me question
whether or not I have made an error following it.
I get an invalid cast error at this code
(DigitalClock1 as ISubject).Attach(fClockTimer as IObserver);
which is actually flipped and should be
(fClockTimer as ISubject).Attach(DigitalClock1 as IObserver);
So, my questions ...
Is the article out of date?
Are these patterns implemented in the base code?
The observer pattern is implemented in tiOPF.
And as an aside, what is the state of tiOPF, I could not get it to
install in Lazarus 1.02.
Version 3 is designed to work with Delphi 2009 and higher.
Graeme Geldenhuys actively maintains tiOPF version 2.
It works definitely with Lazars 1.0.2, I use it myself.
Michael.
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