可以捕獲一個子模式的任何值，通過匹配它對應的一個標識符： > It is possible to catch any value of a sub-pattern by matching it against an identi?er: ~~~ var myTree = Node(Leaf("foo"), Node(Leaf("bar"), Leaf("foobar"))); var name = switch(myTree) { case Leaf(s): s; case Node(Leaf(s), _): s; case _: "none"; } trace(name); // foo ~~~ 這會返回如下之一： > This would return one of the following: * 如果 myTree 是一個 Leaf，它的name 被返回 * 如果myTree 是一個 Node，并且左側的子樹是一個 Leaf，它的name被返回（這應用在這里，返回“foo”） * 否則 “none”被返回 > * If myTree is a Leaf, its name is returned. > * If myTree is a Node whose left sub-tree is a Leaf,its name is returned (this will apply here, returning "foo"). > * Otherwise "none" is returned. 還可以使用 = 來捕獲值，這更進一步的匹配： > It is also possible to use = to capture values which are further matched: ~~~ var node = switch(myTree) { case Node(leafNode = Leaf("foo"), _): leafNode; case x: x; } trace(node); // Leaf(foo) ~~~ 這里 ，如果輸入匹配 leafNode 是綁定到 Leaf("foo") 。在所有其他情況，myTree 本身是被返回：case x 工作方式類似于 case \_ ，它匹配任何，但是使用一個i額標識名稱如 x ，它也會綁定匹配的值到這個變量。 > Here, leafNode is bound to Leaf("foo") if the input matches that. In all other cases, myTree itself is returned: case x works similar to case \_ in that it matches anything, but with an identi?er name like x it also binds the matched value to that variable.