On Mar 26, 2014, at 4:17 AM, Ulf Zibis <[email protected]> wrote:
> See also:
> . . .
> http://mail.openjdk.java.net/pipermail/coin-dev/2009-March/001180.html
This last one has a specific proposal, which is simple and quite nice. The
important idea is
that we don’t actually make any change to the code of void methods or make them
actually
return anything; instead, the caller takes notice of situations where an
invocation of
a void method is used as a subexpression whose value is required (heretofore
forbidden
by the language) and gives it a special interpretation.
I note that Ulf’s proposal applies only to method invocations, but I note that
the same
technique could be used to include field references if desired.
I am wholeheartedly in favor of allowing “chaining” of dotted expressions such
as
CharBuffer.allocate(26).position(2).put("C").position(25).put("Z”)
I am a bit more skeptical about expressions that begin with a dot because of
potential
confusion about which expression is referred to:
myVeryLongNamedString.subString(.indexOf("C”), .indexOf("Q”))
seems clear enough, but what about:
myVeryLongNamedString.subString(.indexOf("C”) + otherString.length(),
.indexOf("Q”))
Does the second occurrence of .indexOf use myVeryLongNamedString or otherString?
A compromise would be to allow leading-dot expressions to occur only within the
arguments
of the method call whose target is the object which the leading-dot expressions
are expected
to use as their target, and if there are such leading-dot expressions within
the arguments
then the arguments must not contain any non-leading-dot field references or
method calls.
Just a thought for discussion. This would be considered a separate mechanism
from the
chaining-of-void-methods mechanism (it was a very clever idea to try to unify
them in Ulf's
original proposal, though).
—Guy
