Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

Copy constructor.

template<
    class OtherAlloc>
basic_fields(
    basic_fields< OtherAlloc > const&,
    Allocator const& alloc);

Name	Description
`alloc`	The allocator to use.