swift234

Introduce another calling syntax for selectors.

This new syntax aims to be closer to the declaration syntax. For
example, to call this method:

  func performSelector(_ : SEL) withObject(obj1 : id)  { }

one would use

  target.performSelector("doThis:") withObject(object)

The additional selector pieces (e.g., withObject(object)) occur on the
same line; otherwise, they are taken as a separate statement. However,
one can use ':' as a continuation character at the beginning of the
next line to continue the message send, e.g.,

  target.performSelector("doThis:")
        :withObject(object)

For the 3-argument version, one could use, e.g.,

  target.performSelector("doThis:") withObject(object1) withObject(object2)

or

  target.performSelector("doThis:")
        :withObject(object1) withObject(object2)

or

  target.performSelector("doThis:")
        :withObject(object1) 
        :withObject(object2)

depending on the width of your screen.

Note that I've tweaked the parsing of case statements slightly to
accommodate this change, by requiring that the ':' that follows a case
statement not start a new line. Thus,

  case foo:

is okay, but

  case foo
    :

is not. This is mostly paranoia, so that

  case target.performSelector("sel"):

is "obviously" a simple method invocation in the case, while

  case target.performSelector("sel")
             :withObject(object):

is "obviously" a two-argument method invocation in the case.

This syntax has some positives, such as similarity with the function
declaration syntax and being a fairly clean extension of the "normal"
Swift method call syntax. It also has some negatives: we have our
first continuation character (':'), the syntax for constructors is
(again) a bit unfortunate

  new NSURL(initWithString="http://www.apple.com")

and it's not clear how to invoke a variadic method with this syntax
without, say, burying the additional arguments in the last argument
(which is currently not permitted), e.g.,

  NSString.alloc().initWithFormat("blah") locale(locale, arg1, arg2)





Swift SVN r4366