Re: Deriving from a STL container

From:
 James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 31 Oct 2007 10:40:02 -0000
Message-ID:
<1193827202.669509.205160@50g2000hsm.googlegroups.com>
On Oct 30, 8:59 pm, Kai-Uwe Bux <jkherci...@gmx.net> wrote:

BobR wrote:

mosfet wrote in message...

Could someone tell me why it's considered as bad practice to inherit
from STL container ?


They do not have virtual destructors.


That's an orthogonal issue. The template classes
std::iterator<> or std::unary_function<> also do not have
virtual destructors, yet they are clearly provided to be
inherited from.


Yes, but they were designed to be base classes, std::vector
wasn't. In this case, I think the difference is that classes
like std::iterator<> don't have any semantics; you'd never,
never have an std::iterator<>* in your program, much less delete
through it. This is a lot less true for std::vector<>*.

My own feeling is that std::vector<> isn't designed for use as a
base class, and so shouldn't usually be used as a base class.
On the other hand, if the use were local and well controled, I
don't think I'd get up in arms about it. I would object to it
if the derived class were some general and widely used
component, however.

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