deduction guides for std::list
Defined in header <list>
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template< class InputIt, class Alloc = std::allocator<typename std::iterator_traits<InputIt>::value_type>> |
(since C++17) | |
This deduction guide is provided for list to allow deduction from an iterator range. This overload participates in overload resolution only if InputIt
satisfies LegacyInputIterator and Alloc
satisfies Allocator.
Note: the extent to which the library determines that a type does not satisfy LegacyInputIterator is unspecified, except that as a minimum integral types do not qualify as input iterators. Likewise, the extent to which it determines that a type does not satisfy Allocator is unspecified, except that as a minimum the member type Alloc::value_type
must exist and the expression std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as an unevaluated operand.
Example
#include <list> #include <vector> int main() { std::vector<int> v = {1, 2, 3, 4}; // uses explicit deduction guide to deduce std::list<int> std::list x(v.begin(), v.end()); // deduces std::list<std::vector<int>::iterator> // first phase of overload resolution for list-initialization selects the candidate // synthesized from the initializer-list constructor; second phase is not performed and // deduction guide has no effect std::list y{v.begin(), v.end()}; }