Cloning an Entity

Duplicating a whole Entity — a prototype crate, a prefab from a level editor, a corpse that should look like the living one — is serialize then deserialize onto a new Entity.

The recipe

local function cloneEntity (world, original)
  local copy = world:newEntity()
  copy:deserialize(original:serialize(true)) -- ignore key
  return copy
end

local crate2 = cloneEntity(world, crate)

Entity:serialize(true) omits key so the copy does not steal the original’s identity. If you want a new key, give("key") after. If you are writing a save, keep keys — that is Serialization, not cloning.

What is not a clone

Entity:getComponents is a shallow copy of fields. The Component tables are the same objects. Mutating copy.position would mutate original.position. Do not use it to clone.

Cloning a Component copies one instance onto an Entity that already exists. Use that when you only want health or sprite, not the whole bundle.

An assemblage plus a few gives is better when serialize is too coarse — when you want a new cat at a new position, not a photocopy including dead.

After the copy

The copy is a new Entity in the World. Components whose serialize returned nil are missing; give those again if the clone should have them (serializable is re-added by default on newEntity).

See also

• Cloning a Component
• Serialization