why this code doesn't work!!

[A. Saksena]

Hi all,
Why this code does't work!!
========================
#include <iostream>
template<typename T>
class a
{
public:
typedef T var;
};

class b
{
};

template<typename T>
void connect(typename a<T>::var& v1,typename a<T>::var& v2){}

int main()
{
a<b>::var v1,v2;
connect(v1,v2);

}
=======================

During compilation with gcc(3.2.3) I get following error:-
$ g++ problem.cpp
problem.cpp: In function `int main()':
problem.cpp:19: no matching function for call to `connect(b&, b&)'

I would expect to template function connect(b&, b&) to exist.

If this is not legal c++. Is there is way way to implement suct a
functionality?


Abhishek

 

[Thomas Maier-Komor]

Hi all,
Why this code does't work!!
========================
#include <iostream>
template<typename T>
class a
{
public:
typedef T var;
};

class b
{
};

template<typename T>
void connect(typename a<T>::var& v1,typename a<T>::var& v2){}

int main()
{
a<b>::var v1,v2;
connect(v1,v2);

}
=======================

During compilation with gcc(3.2.3) I get following error:-
$ g++ problem.cpp
problem.cpp: In function `int main()':
problem.cpp:19: no matching function for call to `connect(b&, b&)'

I would expect to template function connect(b&, b&) to exist.

If this is not legal c++. Is there is way way to implement suct a
functionality?


Abhishek

I think the correct template parameter cannot be deduced.
If you supply it explicitly it works (g++ and Sun's CC)

i.e.:
connect<b>(v1,v2);

Tom

 

[joginder.singh]

Hi all,
Why this code does't work!!
========================
#include <iostream>
template<typename T>
class a
{
public:
typedef T var;
};

class b
{
};

template<typename T>
void connect(typename a<T>::var& v1,typename a<T>::var& v2){}

int main()
{
a<b>::var v1,v2;
connect(v1,v2);

}
=======================

During compilation with gcc(3.2.3) I get following error:-
$ g++ problem.cpp
problem.cpp: In function `int main()':
problem.cpp:19: no matching function for call to `connect(b&, b&)'

Replace the line 19 to read:

connect<b>(v1,v2);

and the code will compile clean. The parameterized implementation of
the function connect(...) is selected only if you pass the parameter(s)
it expects.

Regards,
Joginder.