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Article #17690Re: multiple inheritance and the VCL
From: Alisdair Meredith
Date: Thu, 06 Mar 2003 11:24
Date: Thu, 06 Mar 2003 11:24
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1903 bytes
Stephan wrote: > The way around this, for you, is to create a class that inherits the TForm > and implements your "common" functionality. > such as: > class TCommonForm: public TForm > > Then, when you create a new form, change the inherated > from "TForm" to "TCommonForm" Not very helpful if you want to add functionality to a group of controls. For instance, we wanted to add our own validation/databinding to several standard VCL controls. We do not control the base class, and our implementation must then rely on knowing each possible derived class in order to cast and handle each correctly. Delphi gets around this using interfaces, supporting Multiple Interface Inheritence for several years. BCB6 finally gets limitted support for this with pure abstract base classes, see similar thread in .language.cpp for details. -- AlisdairM Team Thai Kingdom
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 10cc67,679d8017f814d3b X-Google-Attributes: gid10cc67,public X-Google-ArrivalTime: 2003-03-06 21:27:23 PST Message-ID: <3E672FE1.C4CC3277@uk.renaultf1.com> Date: Thu, 06 Mar 2003 11:24:17 +0000 From: Alisdair Meredith <alisdair.meredith@uk.renaultf1.com> X-Mailer: Mozilla 4.75 [en] (Windows NT 5.0; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: borland.public.cppbuilder.nativeapi Subject: Re: multiple inheritance and the VCL References: <3e64d1be@newsgroups.borland.com> <3e64e3b0$1@newsgroups.borland.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit NNTP-Posting-Host: 195.153.139.2 X-Trace: newsgroups.borland.com 1046949858 195.153.139.2 (6 Mar 2003 03:24:18 -0800) Lines: 24 Path: arc1-ca.pugleaf.net!archiver1.google.com!news1.google.com!sn-xit-02!sn-xit-03!sn-xit-06!sn-xit-08!supernews.com!news-out.visi.com!petbe.visi.com!newsfeed.wirehub.nl!news.kweb.on.ca!KWeb!newsgroups.borland.com!not-for-mail