I'm struggling to make my class be a friend of a template in its parent namespace. Can someone explain what I'm doing wrong:
Here are my attempts and their errors with MSVC8 (Visual Studio 2005):
namespace a {
namespace b {
template<typename T>
class x;
namespace c {
class y
{
template<typename T>
friend class x;
...
};
}
}}
error C2888: a::b::x : symbol cannot be defined within namespace c
namespace a {
namespace b {
template<typename T>
class x;
namespace c {
class y
{
template<typename T>
friend class ::a::b::x;
...
};
}
}}
error C2888: a::b::x : symbol cannot be defined within namespace c
namespace a {
namespace b {
namespace c {
class y
{
template<typename T>
friend class ::a::b::x;
...
};
}
}}
error C2039: x : is not a member of a::b
I can't just include the header file containing class x as it depends on class y leading to a circular inclusion.
A hack workaround: If you know the all specific types the template will ever be instantiated with, befriend each instantiation rather than the template. For example:
namespace a {
namespace b {
template<typename T>
class x;
namespace c {
class y
{
friend class x<char>;
friend class x<wchar_t>;
...
};
}
}}