![]() |
Home | Libraries | People | FAQ | More |
Fusion pair type is a half runtime pair. A half runtime pair is similar to a std::pair, but, unlike std::pair, the first type does not have data. It is used as elements in _map_s, for example.
template <typename First, typename Second> struct pair;
Parameter | Description |
---|---|
First | The first type. This is purely a type. No data is held. |
Second | The second type. This contains data. |
Notation
Expression | Semantics |
---|---|
P::first_type | The type of the first template parameter, F. |
P::second_type | The type of the second template parameter, S. |
P() | Default construction. |
P(s) | Construct a pair given value for the second type, s. |
P(p2) | Copy constructs a pair from another pair, p2. |
p = p2 | Assigns a pair, p1, from another pair, p2. |
make_pair<F>(s) | Make a pair given the first type, F, and a value for the second type, s. The second type assumes the type of s |
o << p | Output p to output stream, o. |
i >> p | Input p from input stream, i. |
p == p2 | Tests two pairs for equality. |
p != p2 | Tests two pairs for inequality. |
#include <boost/fusion/support/pair.hpp>
pair<int, char> p('X'); std::cout << p << std::endl; std::cout << make_pair<int>('X') << std::endl; assert((p == make_pair<int>('X')));
Copyright © 2001-2005 Joel de Guzman, Dan Marsden |