CEP-0051: Advanced Ownership Move-Out APIs¶

Summary¶

Catalyst should eventually decide how explicit move-out and replacement APIs work for subobjects and containers.

V1 forbids or defers moving out of fields, array/slice elements, optional payloads, dereferenced pointers, globals, module bindings, and captured outer variables.

Example¶

Possible future shape:

fn take_name(user: *mut User) String {
  return move user.name
}

fn pop_front(items: *mut std.collections.Vec(String)) ?String {
  return items.take_at(0)
}

The proposal must decide how moved-out places are tracked, replaced, and cleaned up without breaking aggregate or container invariants.

Motivation¶

Moving out of subobjects is useful for containers and ownership-heavy code. It introduces partial initialization states, invariant preservation, cleanup ordering, and replacement requirements.

Proposed Direction¶

The proposal should cover:

• field move-out;
• array and slice element move-out;
• optional payload take APIs;
• pointer and container move-out;
• partial-move aggregate/container states;
• invariant-preserving replacement APIs.

V1 Compatibility¶

V1 uses whole-binding move plus explicit type/container APIs where accepted.

Related Details¶

• Move Expressions
• Ownership and Resources
• Reference and Mutability