Overview of Move Semantics

Move semantics transfer an object's owned state instead of copying it. In Quxlang, a move constructor receives the source as TEMP&:

.CONSTRUCTOR FUNCTION(@OTHER TEMP& buffer)
{
  .data <-> OTHER.data;
  .size <-> OTHER.size;
}

The source remains a live object after the constructor and will still be destroyed. The move constructor must leave it in a safe moved-from state.

Forwarding a reference category

Generic code uses FORWARD(name) to preserve whether a reference is mutable, constant, or temporary:

::relay FUNCTION(@ARG:value AUTO& AUTO): DECLTYPE(value)
{
  RETURN FORWARD(value);
}

FORWARD does not move by itself. It passes the reference category onward so a later call can choose a copy or move overload.

Movement semantics

destination := source; assigns an existing object. Constructing a new object from a forwarded temporary is what selects a move constructor:

VAR destination buffer := FORWARD(source);

Relocatable structures

STRUCT TRIVIALLY_RELOCATABLE permits the compiler to transfer an object by copying its representation and transferring its lifetime. Ordinary copies keep their copy-constructor behavior. Templates can select the promise with TRIVIALLY_RELOCATABLE_IF(condition). See the relocation contract.

Reference

For TEMP&, forwarding constraints, moved-from lifetime, and generated move rules, see the Move Semantics Reference.