# whenElementKnown

abstract fun whenElementKnown(action: Action<in T>)(source)

Registers an action to execute when an element becomes known. The action is only executed for those elements that are required. Fails if any element has already been finalized.

#### Since

4.5

#### Parameters

action

The action to execute for each element becomes known.

abstract fun <S> whenElementKnown(type: Class<S>, action: Action<in S>)(source)

Registers an action to execute when an element of the given type becomes known. The action is only executed for those elements that are required. Fails if any matching element has already been finalized.

#### Since

4.5

#### Parameters

type

The type of element to select.

action

The action to execute for each element becomes known.