Restrictions ​

The API omits sanity checks in areas that would be costly to do so, allowing you to run into problems like iterator invalidation and undefined behavior. This means that there are certain restrictions on what you can do. All restrictions are documented here and at the relevant API references.

Signals ​

• Listeners cannot disconnect other listeners. Listeners can disconnect themselves.

• The registry cannot be modified within a listener, you cannot add or remove components, and create or destroy entities.

Modifying During Iteration ​

This applies to the iteration of views, observers and groups.

• During iteration, adding or removing components from entities not currently being iterated can invalidate the iterator.

Pools ​

storage() returns the underlying storages used by the registry to store entities and components. You can use these for more direct access than views and also modify the values of Pool.values directly.

• Changing Pool.entities or Pool.size is undefined behavior.

Releasing Ids ​

• Destroying an entity that still has components with release() is undefined behavior.

Multithreading ​

• Components can be added or removed during iteration as long as it is the only thread doing so for that set of components.

  This does not apply if a component in that set belongs to a group that has other group components being used in another thread, e.g One thread can add/remove component X and another thread can add/remove Y and Z as long as X is not grouped with Y or Z.

• The same set of components can be iterated by multiple threads at the same time if they are reading only.