autoRemoveTarget auto-removes the source?

[timsdsdio]

Perhaps I'm confused on the naming here but it feels like the only way to interpret this property in a way that lines up with what it does is to read it as "this is an auto-remove target" rather than "this will auto-remove the target". Could someone help me to understand how to properly interpret this?

To use the example from the docs:

const ChildOf = relation({ autoRemoveTarget: true })

const parent = world.spawn()
const child = world.spawn(ChildOf(parent))
const grandchild = world.spawn(ChildOf(child))

parent.destroy()

world.has(child) // False, the child and grandchild are destroyed too

In this situation, the target of ChildOf(parent) is parent, correct? But creating that relationship doesn't result in parent being automatically destroyed when child is (it's the opposite).

Am I mixing up what "target" means in this context?
Thanks for the help.

p.s. Seems every library I use by pmndrs is excellent. Kudos on the great work.

[krispya]

Thanks for bringing this up and the kind words! You are right there is some confusion in the language here. Relations allow you to create a graph with entities and this option is meant to ensure there are no orphans. By default when an entity is destroyed then any relation that points to it will also be destroyed, ie.

const ChildOf = relation()

const parent = world.spawn()
const child = world.spawn(ChildOf(parent))
parent.destroy()

child.has(ChildOf('*')) // false

But now we want to enforce no orphans.

const ChildOf = relation({ autoRemoveTarget: true })

const parent = world.spawn()
const child = world.spawn(ChildOf(parent))
parent.destroy()

child.isAlive() // false

Okay but as you pointed out the word target is being used to mean the subject here. Child is actually the subject of the relation. And this assumes that the graph is built by the children pointing to the parents instead of the parents pointing to the children. Both could be a good practice depending on the app design so I am thinking better would be this:

// Searches subject to target, ie is anyone pointing to me the destroyed entity with this relation?
const ChildOf = relation({ destroyOrphans: 'subject' })
// Searches target to subject, ie is the destroyed entity pointing to another entity with this relation?
const ParentOf = relation({ destroyOrphans: 'target' })