Programming Forums - The STL is really neat

http://www.sgi.com/tech/stl/table_of_contents.html

I don't know why I never realized it before, but the STL is really, really neat. The STL idea of concepts combined with boost::concept_traits allows you to check that template parameters pass certain requirements.

Example:

#include <iostream>

#include <vector>



#include <boost/concept_check.hpp>





template <typename InputIterator>

void display( InputIterator begin, InputIterator end ) {

    using namespace boost;

    

    function_requires<InputIteratorConcept<InputIterator> >();

    

    for (; begin != end; begin++ )

        std::cout << *begin;

    

    std::cout << std::endl;

}



int main() {

    std::vector<int> numbs;

    

    for ( int x = 0; x < 10; x++ )

        numbs.push_back( x );

    

    display( numbs.begin(), numbs.end() );

}

If I've done that right, it will only compile if the type of iterator passed to the display() function complies by the Input Iterator concept defined by the STL.

Here's another example:

template <typename Integer>

bool isEven( Integer n ) {

    using namespace boost;

    

    function_requires<IntegerConcept<Integer> >();

    

    return !(n & 1);

}



int main() {

    std::cout << isEven( 314 ) << std::endl; // Is fine --> concept check passes

    std::cout << isEven( 4.2 ) << std::endl; // BAD --> compile error

}

C++ continues to astound me with what it's capable of. :eek: