Suppose type foo_t
with a named constructor idiom, make_foo()
. Now, I want to have exactly 123 foo's - no more, no less. So, I'm thinking about an std::array<foo_t, 123>
. Now, if foo_t
were default-constructible, I would write:
std::array<foo_t, 123> pity_the_foos;
std::generate(
std::begin(pity_the_foos), std::end(pity_the_foos),
[]() { return make_foo(); }
);
and Bob's my uncle, right? Unfortunately... foo_t
has no default ctor.
How should I initialize my array, then? Do I need to use some variadic template expansion voodoo perhaps?
Note: Answers may use anything in C++11, C++14 or C++17 if that helps at all.
The usual.
template<size_t...Is>
std::array<foo_t, sizeof...(Is)> make_foos(std::index_sequence<Is...>) {
return { ((void)Is, make_foo())... };
}
template<size_t N>
std::array<foo_t, N> make_foos() {
return make_foos(std::make_index_sequence<N>());
}
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