Stefan Slapeta wrote:

Rich Sposato wrote:

...

1. You can search on any type that is comparable to the key_type, rather than just the key_type. (The STL associative containers only allows searches on the same type as the key.)

BTW, there is also an extention in STLPort which supports comparisons like > this.

When I asked about this at STLport, they said they don't have extensions to the STL. Maybe I did not ask the right question.

I often wondered why this isn't supported by the standard containers. Any idea?

I must caution that flex_set has a minor disadvantage, a problem which std::set does not have. For primitive types, flex_set will cause code-bloat, while std::set will not. I don't use flex_set with primitive types because the compiler will make 2 functions out of this code for flex_set< long >, while it only makes one function using std::set< long >. typedef std::set< long > bunchOfLongs; long a = 1; short b = 2; bunchOfLongs.erase( a ); bunchOfLongs.erase( b ); The compiler will see flex_set< long >::erase( const long & ); as different from flex_set< long >::erase( const short & ); But, a compiler will see both of those calls above as: std:set< long >::erase( const long & ); For that reason, I can't advocate changing std::set's functions to be templated the way flex_set functions are. I suppose if it had templated functions like flex_set, there would be no need for flex_set, and somebody would some day advocate using a less-templated class called no_bloat_set. :-) I actually consider the bloat issue as minor because most of the functions are inline and small. Also, I rarely do a search using more than one type anyway. My typical usage with flex_set and related classes is to insert using the key_type, and find, count, and erase using a different type. Sometimes, the amount of code actually decreases inspite of a little bloat because I don't have to construct a temporary anymore. I think that could answer why the associative containers like map do not have templated functions. As to the other container types, I don't think they will need templated search functions. If you use the sequential containers, you can use the stand-alone find, count, binary_search, etc... functions and pass in a predicate. Rich