Re: Confused by template method lookups
On 14 Aug., 13:49, Oscar Schnitzer <oscarschnit...@yahoo.com.au>
wrote:
I'm porting a large C++ library from Visual C++ 9.0 to g++ 4.4.1 and
have run into a problem that is puzzling me. The following is a very
cut-down version of the problematic code:
namespace foo {
template<typename T>
class Y
{
public:
Y (T t_) : t (t_) {}
T add (T other) const {
return add (t, other); // Fails here
}
private:
const T t;
};
template<typename T>
T add (T t1, T t2)
{
return t1 + t2;
}
}
int main (int argc, char *argv[])
{
Y<double> y (3.0);
double result = y.add (7.1);
}
This problem is not related to templates. You can even cut it further
down to
void add(int, int);
class Y {
void add(int) {
add(2,3); // fails
}
};
This is a classic case of name hiding. Y::add hides ::add. You even
cannot rely on ADL (argument dependent name lookup):
namespace foo {
struct xxx {};
void add(xxx, xxx);
}
namespace bar {
class Y {
void add(int) {
foo::xxx a, b;
add(a,b); // ERROR, no ADL is done
}
};
void f() {
foo::xxx a, b;
add(a,b); // ok, foo::add found via ADL
}
} // namespace bar
hope this helps,
SG
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