三冒号 Scala
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Triple colon Scala
提问by providence
I'm trying to pick up some scala. Reading through examples I came across this impossible-to-google nugget:
我正在尝试获取一些 Scala. 通读示例，我发现了这个不可能通过谷歌搜索的金块：
case 3 => l ::: List(3)
What does the triple colon accomplish?
三结肠有什么作用？
回答by Aaron Novstrup
To add to gkamal's answer, it's important to understand that methods whose names end in a colon are right-associative. So writing l ::: List(3)is the same as writing List(3).:::(l). In this case it doesn't matter since both operands are lists, but in general you'll need this knowledge to find such methods in the scaladocs.
要添加到gkamal 的答案中，重要的是要了解名称以冒号结尾的方法是右结合的。所以写作和写作l ::: List(3)是一样的List(3).:::(l)。在这种情况下，这并不重要，因为两个操作数都是列表，但通常您需要这些知识才能在 scaladocs 中找到此类方法。
It also helps to know that the scaladocshave a comprehensive index of all methods (and classes, etc) with symbolic names. You can reach it by clicking on the #in the upper-left corner.
