diff options
Diffstat (limited to 'src/library/scala/collection/mutable/Builder.scala')
| -rw-r--r-- | src/library/scala/collection/mutable/Builder.scala | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/src/library/scala/collection/mutable/Builder.scala b/src/library/scala/collection/mutable/Builder.scala index 75560580cc..8d6a0ec69d 100644 --- a/src/library/scala/collection/mutable/Builder.scala +++ b/src/library/scala/collection/mutable/Builder.scala @@ -18,6 +18,14 @@ import generic._ * elements to the builder with `+=` and then converting to the required * collection type with `result`. * + * One cannot assume that a single `Builder` can build more than one + * instance of the desired collection. Particular subclasses may allow + * such behavior. Otherwise, `result` should be treated as a terminal + * operation: after it is called, no further methods should be called on + * the builder. Extend the [[collection.mutable.ReusableBuilder]] trait + * instead of `Builder` for builders that may be reused to build multiple + * instances. + * * @tparam Elem the type of elements that get added to the builder. * @tparam To the type of collection that it produced. * @@ -36,8 +44,10 @@ trait Builder[-Elem, +To] extends Growable[Elem] { */ def clear() - /** Produces a collection from the added elements. - * The builder's contents are undefined after this operation. + /** Produces a collection from the added elements. This is a terminal operation: + * the builder's contents are undefined after this operation, and no further + * methods should be called. + * * @return a collection containing the elements added to this builder. */ def result(): To @@ -112,6 +122,8 @@ trait Builder[-Elem, +To] extends Growable[Elem] { * @tparam NewTo the type of collection returned by `f`. * @return a new builder which is the same as the current builder except * that a transformation function is applied to this builder's result. + * + * @note The original builder should no longer be used after `mapResult` is called. */ def mapResult[NewTo](f: To => NewTo): Builder[Elem, NewTo] = new Builder[Elem, NewTo] with Proxy { |