Re: template -> instance -> function unresolved ???
Mario Semo wrote:
in the following sample i have a template class (wrapping a pointer) and a
friend template function accessing private data in the template.
i compile this into a dll (yes i know, there is no exported function from
this dll, but this is just a sample) and
get an unresolved external - the friend function is used, but not
instantiated.
Question: what if you use that code outside a DLL in a normal executable?
Other than that, there are some requirements on friends of templates, in
particular if those depend on the template parameter. I believe that is
explained in the C++ FAQ at parashift's, but I think the gist is that you
have to declare the function before the class who's friend it is supposed
to become.
Further...
template <class Element>
class IElemPointer
{
friend Element& elementForOps (IElemPointer <Element>&);
[...]
};
....this declares a function as a friend, but...
template <class Element>
Element&
elementForOps (IElemPointer <Element>& ptr)
{ return *(ptr.ivPtr); }
....this is an equally named function _template_, which has not been declared
a friend, and I think that is also the problem you are having.
My suggestion BTW would be to simply overload unary operator* as a member,
but of course that doesn't answer the question why this here doesn't work
and might not match your design.
Uli
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