collect/filter on type

On Wed, Jun 22, 2011 at 9:31 AM, wookietreiber <kizkizzbangbang@googlemail.com> wrote:

has this been implemented yet in some way:

scala> val l = List[Foo](foo,bar,foo,bar,foo)
l: List[Foo] = List(foo, bar, foo, bar, foo)

scala> l.collect[Bar]

... to get only certain subtypes of a collection?

Here's mine, but it doesn't work with boxed primitives--I haven't bothered to figure out how to do that yet. :)

  /**
   * Filters the provided collection for elements that are assignable 

   * from the class of the type parameter
   */
  def filterByType[X : Manifest](in: Traversable[_]): List[X] = {
    in.collect {
      case x if manifest[X].erasure.isInstance(x) => x.asInstanceOf[X]
    }.toList
  }

-0xe1a 

Do you mean this?

scala> l.collect {case b:Bar => b}
res4: List[Bar] = List(bar, bar)

thx for the replies, I toyed with it a little and had similar solutions, like:

On Wed, Jun 22, 2011 at 10:04:15AM -0700, Dave wrote:
> Do you mean this?
>
> scala> l.collect {case b:Bar => b}
> res4: List[Bar] = List(bar, bar)

it just would be nice to have the even more concise syntax:

l.collect[Bar]

directly in the collection library for something I guess is needed often, this
would be even shorter and more expressive :) even for DSLs if written like:

list filter [Bar] or
list collect [Bar]

best regards
wookietreiber