[fpc-pascal] Is it posible to implement more than one interface in a class defination?

Graeme Geldenhuys graemeg.lists at gmail.com
Sun Nov 14 17:49:35 CET 2010

Hi Everybody,

On 14 November 2010 16:31, Jonas Maebe wrote:
> Please don't spread FUD. There are several projects that make heavy use of
> interfaces that work fine with FPC (e.g. Zeoslib). Yes, interface delegation
> is not finished (other than that, interfaces work fine afaik)

Let me just clarify. I did not have a "dig" at anybody or the FPC
team. I simply wanted to make the original poster aware of the
limitation of FPC's Interfaces implementation to date. And no Jonas,
there are still plenty of things missing from FPC's implementation,
and thus it proves that hardly anybody in the FPC core team uses
Interfaces now or in the past.

 Two major issues (but not the only items I can list):
   * incomplete delegation (non existent in FPC 2.4.2)
   * No name resolution (function aliases) of conflicting interfaces

Unfortunately these are rather critical features in normal to advanced
interface usage in software. If you haven't used them yet, then you
have only scratched the surface of what Interfaces are useful for. So
at this point, only the most basic usage (aka reference counting -
memory management) of Interfaces work in FPC.

> after the "interface scoping" thread on fpc-devel). If things continue like
> this, I will start holding all of your mails for moderation and only allow
> them through on a case-by-case basis, because the current situation is not
> tenable.

And we here start again. By all means, if it will make you feel
better/happier, then why not simply unsubscribe or band my from all
FPC and Lazarus related mailing lists while you are at it. For Gods
sakes, I was simply trying to help somebody by mentioning potential
problems when using FPC's Interfaces in "real world applications". If
you come from Delphi or Kylix to Free Pascal, you as a developer
should be made aware of these things. In fact, there should actually
be a wiki page dedicated to what FPC cannot do compared to Delphi or
Kylix. This would seriously help developers wanting to move to Free
Pascal, to evaluate FPC better before they make a decision. I see no
harm in letting developers know what FPC cannot do yet, this might
even help new contributors with ideas of what they can implement so
FPC can move forward.

  - Graeme -

fpGUI - a cross-platform Free Pascal GUI toolkit

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