Over the weekend, I had specific problem with function overload resolution that I can't seem to solve. The code below is a distillation of the problem:
#include <iostream>
using namespace std;
template<typename T>
void f(const T& t)
{
cout << "In template function." << endl;
}
class C
{
public:
void f() { cout << "In class function." << endl; }
void g() { int i=0; f(i); }
void h() { int i=0; f<int>(i); }
void i() { extern void f(int); int i=0; f(i); }
};
int main()
{
cout << "Test" << endl;
C c;
c.i();
return 0;
}
1) C::g won't compile because the compiler won't try the template. It just complains that there is no C::f to match.
2) C::h won't compile for no reason that is obvious to me. The message is "expected primary-expression before 'int'"
3) C::i will compile, but (after commenting out g and h) it won't link to anything. I think I understand this: the extern is forcing the linker to look into another compilation unit, but any template definition would be in this compilation unit.
I would appreciate any clarification on the reasons for 1 and 2. Also, ultimately, can someone suggest a way to get this to work that doesn't involve creating another compilation unit?
Likely it is finding C::f
instead of global f
. Use ::f<int>(i)
.
Look here: http://ideone.com/zs9Ar
Output:
Test
In template function.
#include <iostream>
using namespace std;
template<typename T>
void f(const T& t)
{
cout << "In template function." << endl;
}
class C
{
public:
void f() { cout << "In class function." << endl; }
void g() { using ::f; int i=0; f(i); }
};
int main()
{
cout << "Test" << endl;
C c;
c.g();
return 0;
}
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With