Multi-line vs single-line method and class constructor declarations and invocations

[jkbradley]

Apache Spark (especially what I've seen of MLlib) and the current Scala style guide differ on one item: Should multiline method and class constructor invocations be written with 1 arg per line or multiple args per line?

Spark mostly uses multiple args per line (for invocation, not for declarations). The current Scala style guide says to put 1 arg per line: See "Methods with Numerous Arguments" here: http://docs.scala-lang.org/style/indentation.html

Can we add our standard to this doc?

E.g.:

• For method and class definitions,
  • If they fit on 1 line, put everything on 1 line.
  • For multi-line definitions, put 1 argument per line.
• For method and class constructor invocations,
  • If they fit on 1 line, put everything on 1 line.
  • For multi-line calls, put (multiple arguments per line) or (1 argument per line)?

[rxin]

How about if it requires more than two lines, one arg per line. If it fits in two lines, just fit them in two lines? That's what I personally do.

[HyukjinKwon]

@rxin and @jkbradley, can I open a PR for describing it? Roughly like:

• For method, class definitions, class constructor invocations,

  • If they fit within 2 line, put everything within 2 line.

    function("very long blabla........................................................")
    

    function(
      "very long blabla........................................................")
    

  • For multi-line, put multiple arguments per line?

    function(
      "very",
      "very long",
      "bla bla bla bla")
    

I think I can quickly do this if we are okay with ^.

[rxin]

sure - sounds good.

[jkbradley]

Sounds good to me

[HyukjinKwon]

@jkbradley, this is fixed in https://github.com/databricks/scala-style-guide/pull/64 :-)