Possible implementations of vararrays

[lerno]

Questions:

1. When empty, is this a null or an empty struct
2. What is the structure holding it?
3. Should it remember its allocator?

[lerno]

Possible data structures:

A. Classic style

struct Vararray
{
  usize size;
  usize capacity;
  Allocator allocator; // Typically 2 pointers wide
  Type *array
}

Stb style:

struct Dynarray
{
  usize size;
  usize capacity;
  Allocator allocator; // Typically 2 pointers wide
  Type array[0]
}

[lerno]

Advantages to (A):

1. Well understood, semantics fairly straightforward.
2. Can be initialized with allocator in a natural way

Disadvantages

1. If stored by value, pretty big.
2. Must guard against accidental copying
3. No advantage over generic array

Advantages of B:

1. Storage is single pointer unless used
2. Self contained, no danger of accidental copying

Disadvantages of B

1. Allocator assignment likely implicit
2. Must pass around pointer to the pointer

[lerno]

B can be have two different semantics as well, depending on how efficient one wants it to be.

[lerno]

Vararrays will be moved into the standard library.