Re: Help needed to overload function template.

Hi Paul, I followed your example and defined the functions like showed
below:

Obs.: the code below is in the cpplib namespace.

     template<
        typename T,
        typename Alloc,
        template<typename, typename> class Container,
        typename Predicate
     >
     Container<T, Alloc>& erase_if(Container<T, Alloc>& c, Predicate p)
     {
         c.erase (std::remove_if (c.begin (), c.end (), p), c.end ());
         return c;
     }

     template<
        typename Key,
        typename T,
        typename Compare,
        typename Alloc,
        template<typename, typename, typename, typename> class
MapClass,
        typename Predicate
     >
     void erase_if(MapClass<Key, T, Compare, Alloc>& map, Predicate p)

     {
         typedef typename MapClass<Key, T, Compare, Alloc>::iterator
iterator;
         iterator it = map.begin ();
         const iterator end = map.end ();
         while (it != end);
         {
             iterator tmp=it++;
             if (p (*tmp))map.erase (tmp);
         }
     }

And called it this way:

....
typedef std::pair<int, std::string> MapEntry;
struct IsDigit : public std::unary_function<MapEntry, bool>
{
   bool operator() (MapEntry p) {return isdigit (p.first);}
};

typedef std::map<int, std::string> Map;

BOOST_AUTO_TEST_SUITE(algorithm_util_suite)

BOOST_AUTO_TEST_CASE(erase_if_map)
{
    Map map;
    map[0] = "a";
    map[1] = "1";
    map[2] = "c";

     cpplib::erase_if (map, IsDigit());
....

And the compiler complained saying it is ambiguous with this message:
||=== cpplib, Debug ===|
C:\projects\cpplib\test\algorithm_util_test.cpp||In member function
`void algorithm_util_suite::erase_if_map::test_method()':|
C:\projects\cpplib\test\algorithm_util_test.cpp|30|error: call of
overloaded `erase_if(Map&, IsDigit)' is ambiguous|
c:\projects\cpplib\algorithm_util.h|16|note: candidates are:
Container<T, Alloc>& cpplib::erase_if(Container<T, Alloc>&, Predicate)
[with T = int, Alloc = std::string, Container = std::map, Predicate =
IsDigit]|
c:\projects\cpplib\algorithm_util.h|31|note: void
cpplib::erase_if(MapClass<Key, T, Compare, Alloc>&, Predicate) [with
Key = int, T = std::string, Compare = std::less<int>, Alloc =
std::allocator<std::pair<const int, std::string> >, MapClass =
std::map, Predicate = IsDigit]|
||=== Build finished: 1 errors, 0 warnings ===|

If I try to fully qualify the call this way:
     cpplib::erase_if<Map::key_type, Map::value_type, Map::key_compare,
Map::allocator_type, Map, IsDigit> (map, IsDigit());

It still does not find it:
C:\projects\cpplib\test\algorithm_util_test.cpp|30|error: no matching
function for call to `erase_if(Map&, IsDigit)'|

Any suggestions ?

Thank you very much for your help.

Best regards,
Mau.

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