Re: C2248: cannot access protected member

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.language
Date:
Thu, 31 Jan 2008 16:29:38 -0500
Message-ID:
<Oy5MjBFZIHA.4860@TK2MSFTNGP03.phx.gbl>
Ben Voigt [C++ MVP] <rbv@nospam.nospam> wrote:

"Igor Tandetnik" <itandetnik@mvps.org> wrote in message
news:OUIS1rEZIHA.4684@TK2MSFTNGP06.phx.gbl...

I guess both of you meant

void (Y::*pf)() = &Y::foo;


No, I meant what I wrote

void (Y::*pf)() = &X::foo;


That still shouldn't compile, due to access check on X::foo, as
described in C++ standard 11.5/1. See my earlier answer in this thread.

I don't know if the C++ compiler will accept that syntax, it should
because it is type safe.


The problem has nothing to do with type safety, but with access control.

Y can access the base implementation of protected member foo, so it
should be able to create a pointer-to-member that does so.


If it were able to do so, it would be able to call foo on some other
class Z derived from X. But it shouldn't be able to call a protected
method on an unrelated class, even if the two share the same base.
--
With best wishes,
    Igor Tandetnik

With sufficient thrust, pigs fly just fine. However, this is not
necessarily a good idea. It is hard to be sure where they are going to
land, and it could be dangerous sitting under them as they fly
overhead. -- RFC 1925

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