Implement keySet() on Multimap. about eclipse-collections HOT 3 CLOSED

An implementation like this would violate invariants.

public Set<K> keySet()
{
  return this.map.keySet();
}

You could just call multimap.keySet().clear() and the Multimap would have a non-zero size but be empty.

I agree that set-like views are important to add, but I don't think we should use the Set interface. We only use Set as the return type for MutableMap.keySet() because the type is inherited from Map.

from eclipse-collections.

Can we return an UnmodifiableSet?

from eclipse-collections.

Yes, and returning it as a SetIterable makes sense in that context. An easy implementation on the immutable side would be to do the same thing, but it would be good to change the return type to ImmutableSet when we are ready to support a more full featured immutable view.

from eclipse-collections.