Emanuel Ziegler <[EMAIL PROTECTED]> writes:
> template <class T>
> class FriendClass
> {
> // This line causes trouble
> friend T get_test<T> (const FriendClass &);
> protected:
> T test;
> };
>
> template <class T>
> T get_test (const FriendClass<T> &fc)
> {
> return fc.test;
> }
>
> int main ()
> {
> FriendClass<int> fc;
> get_test(fc);
> return 0;
> }
>
> --->8---
>
> compiled without any problems before, it now gives the errors
> error: 'get_test' is neither function nor member function; cannot
> be declared friend
> error: expected ';' before '<' token
> in 4.0.2. But I'm pretty sure it's valid C++ code.
I'm pretty sure it isn't.
Declare get_test before FriendClass and you should be fine:
template <class T>
class FriendClass;
template <class T>
T get_test (const FriendClass<T> &);
template <class T>
class FriendClass
{
// This line causes trouble
friend T get_test<> (const FriendClass &);
...
> Another problem concerns inheritance. Although members are declared
> protected and inheritance is public, the members are not transferred
> into the scope of the derived class:
>
> ---8<---
>
> template <class T>
> class Base
> {
> protected:
> int test;
> };
>
> template <class T>
> class Derived : public Base<T>
> {
> protected:
> // This doesn't work
> /* using namespace Base<T>; */
> // This works but should be useless and is unhandy
> using Base<T>::test;
Indeed.
> void set_test ()
> {
> test = 0;
The compiler is correct again.
For some T's, there might be a specialization for Base<T> that doesn't
declare a member test. The (apparent) Base class template is therefore
not considered when the name test is looked up.
If you write
this->test = 0;
, test becomes a dependant name, which causes its lookup to be defered
to instantiation time. At that time, the inherited test will be taken
into consideration.
> Anyone else experienced similar problems?
Certainly.
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