[fpc-devel] Recent added support for Observer pattern in FCL

Graeme Geldenhuys graeme at geldenhuys.co.uk
Tue Aug 28 09:51:38 CEST 2012

On 28/08/12 02:48, Luiz Americo Pereira Camara wrote:
> Back in 2010, in the thread about observer support in fcl, i asked if
> the actions would be customizable so i could, e.g., notify/observe if a
> child was added or removed in a tree structure. The answer was yes.

I've emailed Michael 2-3 weeks ago about a previous mailing list 
discussion about Observer support too - which I concluded as will be 
accepted, Michael just needs time to commit his changes. Adding support 
for Observer into base RTL classes (not FCL). Any extra resources will 
only be used when the Observer functionality is actually requested, by 
the developer, it can't break any existing code because no such 
functionality existed before etc. Michael said it was "again under 
discussion" behind closed doors, but he will notify me of the outcome.

Myself, and I know Michael van Canneyt too, would really like Observer 
support in base RTL classes. This is immensely useful, and means other 
downstream features like a total replacement for db-aware components 
(which Michael also started on already) could be implement in projects 
like Lazarus, fpGUI etc. I can already use the latter to some degree, 
with the help of tiOPF, but sometimes I want other observer 
functionality in my apps too, or don't want to depend on tiOPF, and 
having to created descendants of base RTL classes defeats the whole point.

> The names of the TFPObservedOperation are not consistent:

A valid point, which I actually never noticed before.

   - Graeme -

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