michael.alexeev@[EMAIL PROTECTED]
wrote:
> Hi All,
>
> Consider the following simple program:
>
> <code>
...snipped
> </code>
>
> Both g++ (4.0.2) and Comeau on-line reject it with the following
> message:
> no instance of overloaded function "std::sort"
> matches the argument list
> The argument types that you used are: (Point2 *, Point2 *,
> <unknown-type>)
> std::sort(array.begin(), array.end(), comparePoints);
>
> If the second comparePoints function (1) is commented out or line (2)
> is modified to look like
> std::sort(array.begin(), array.end(),
> std::ptr_fun<const Point2&, const Point2&, bool>(comparePoints));
> then everything compiles fine.
>
> Unfortunately both walkaround are unacceptable for different reasons.
> Any other possibilities?
I could think of two ways.
1) use an explicit cast. This is much like your second workaround, which
was unacceptable for a 'different' reason. So perhaps that reason
forbids this one too.
2) Use a wrapper function that is not overloaded.
Here is the modified code that does compile
<code>
#include <vector>
#include <algorithm>
struct Point2 {};
struct Point3 {};
bool comparePoints(const Point2& iP0, const Point2& iP1)
{return true;}
bool comparePoints(const Point3& iP0, const Point3& iP1)
{return true;}
typedef bool (*Point2PredPtr)(const Point2& , const Point2& );
// 1 typedef used in explicit cast
inline bool comparePoints2(const Point2& iP0, const Point2& iP1)
{return comparePoints(iP0, iP1);}
// wrapper function with a different (non overloaded) name
int main()
{
std::vector< Point2 > array;
std::sort(array.begin(), array.end(), (Point2PredPtr) comparePoints);
std::sort(array.begin(), array.end(), comparePoints2);
}
</code>
Geert-Jan Giezeman
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