Is array of temporaries possible?

Question

Move supports to steal temporary object's internals to avoid copying. Is it possible to create raw array of temporary objects? i.e. vector does not belong to this category.

struct Employee{};

Employee{}; // this creates temporary
Employee [10]; // compiler error, expected identifier before numeric constant

@tadman There is [this](https://wandbox.org/permlink/1F5lcq4DHAjBwo6A). — Passer By, Apr 09 '19 at 03:15
@PasserBy Interesting, but *why*? This seems wildly over-complicated. — tadman, Apr 09 '19 at 03:36
@tadman If you don't want an extra allocation and `std::initializer_list` is inappropriate, you might want to do this. — Passer By, Apr 09 '19 at 03:43

score 1 · Answer 1 · answered Apr 10 '19 at 02:22

Yes, there can be materialized array prvalues. You need to use a type alias though, as the type specifier for the case T{} must be a single identifier:

using array_t = Employee[10];
array_t{};

The prvalue can undergo array-to-pointer conversion too, e.g.:

void func(Employee const* ptr);
// ...
func( array_t{} );

score 0 · Answer 2 · answered Apr 10 '19 at 02:20

The only good way to prolong the lifetime of the temporary is to get and hold reference to const to it.

Something like this might work

using Ecref = const Employee&;

Ecref a[10] = {Employee("John"), Employee("Mary"), ...};

But, unfortunately, arrays of references (const and non-const as well) are forbidden in C++.

Is array of temporaries possible?

2 Answers2