Scala调用链接

Question

Would you write:

(ontDrugFormXml \ "VPID").headOption map
    (id => graph.addE(vertex, searchDmdVertex(graph, "VMP", id.text), "has")) orElse
    (throw new IllegalStateException("VPID required"))

or:

  (ontDrugFormXml \ "VPID").headOption
    .map(id => graph.addE(vertex, searchDmdVertex(graph, "VMP", id.text), "has"))
    .orElse(throw new IllegalStateException("VPID required"))

Which one is proper to you?
Can't have the answer on http://docs.scala-lang.org/style/method-invocation.html

Answer 1

Like this:

(ontDrugFormXml \ "VPID").headOption map { id =>
    graph.addE(vertex, searchDmdVertex(graph, "VMP", id.text), "has")
} orElse (throw new IllegalStateException("VPID required"))

The scala style guide requires infix notation for methods like map that take a function argument. Parameters should be on the same line as the opening brace, eg next to map . orElse should be one the same line as the value it takes.

Answer 2

Infix, the first option. I always use infix notation for orElse.