[fpc-devel] class abstract, class sealed implementation. please review.

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Florian Klaempfl <florian at freepascal.org>:

> Marco van de Voort schrieb:
> > In our previous episode, Florian Klaempfl said:
> >>> This is exactly my point about sealed classes. When you design the
> >>> product or class, you have NO way of know what will come in the
> >>> future. So you need to stay flexible to change! Yet another OOP
> >>> principal that "sealed" tries to prevent!
> >> This might be true, but what's the difference with private etc.?
> > 
> > Private is typically used in nearly every class, sealed in exceptional
> > cases. At best.
> 
> I meant regarding "flexibility". Declaring a member private makes things
> also less flexible.

The main difference is that "private" restricts visibility, whilst "sealed" restricts extensibility. The former is usually a good thing, the latter not.


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