Remove elements without losing capacity

[Ali Çehreli]

On 10/4/22 10:59, Riccardo M wrote:

 > The inherent reason for `remove` to cancel previous capacity and
 > requiring new allocations is exactly to prevent overwriting data that
 > could be owned by something else?

Yes.

A related topic is how the "end slice" never loses that capacity:

void main() {
     auto a = [ 1, 2 ];
     auto b = a;

     assert(a.capacity != 0);
     assert(b.capacity != 0);

     b.length--;
     assert(b.capacity == 0);
     assert(a.capacity != 0);    // <-- Preserved
}

Aside: .capacity is an expensive operation that requires some levels of 
table lookups in the druntime. A data structure would benefit a lot if 
it kept its own capacity as a member variable.

Ali