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From: "Daniel Parker" <danielp@nospam.com>
Subject: Re: Why is granting friendship to a templ. parameter ill-formed?
Date: 1998/03/17
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Srinivas Vobilisetti wrote in message <35082F4C.44C3@usa.net>...
>Christopher Eltschka wrote:
>>
>What actually I meant is something
>like the following:
>
>class A {
>};
>
>class B {
>};
>
>class C {
>};
>
>class D {
>};
>
>template <class T> class X {
>
>friend class T = A, B, C;
>
>// [...]
>};
>
>The statement "friend class T = A, B, C;" means class A is friend of
>class X<A>, class B is friend of class X<B> and class C is friend of
>class X<C> but class D is not a friend of class X<D>. It also means
>class A is not a friend of class X<S != A>.
>
>By doing this, template class X knows what all classes have access to
>its private members. Otherwise, template classes will turn out to be a
>maintenance nightmare.

But surely this depends on context.  If I design a class that can take
plugins in the form of a template parameter, and if I follow your policy by
explicitly listing each plugin as a friend, then, in order to add another
plugin, a client would have to modify this list of friends, which is code
that he may not own.  This would certainly lead to a much bigger maintenance
nightmare.

--
Please do not use reply, use danielp@anabasis.com instead.
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