From: nobu.nokada@...
Date: 2003-11-07T12:01:21+09:00
Subject: Re: ruby-dev summary 21637-21729

Hi,

At Fri, 7 Nov 2003 10:42:51 +0900,
Joel VanderWerf wrote:
> > In 1.8, this is concatenated at compile-time. :)
> > 
> >   s = "this is a string #{		# And you can write
> >       ""}that I have chosen to break #{	# comments!
> >       ""}into multiple lines"
> > 
> 
> Very cool! It doesn't need the "", though, does it?
> 
> irb(main):001:0> "foo#{
> irb(main):002:0" }bar"
> => "foobar"

It needs for compile-time concatenation, because nil.to_s might
be replaced.

  $ ruby -rNodeDump -e '"foo#{' -e '}bar"'
  NodeDump V0.9

  NODE_NEWLINE:  [-e:1]
    NODE_DSTR: "foo"
      NODE_EVSTR:
      NODE_STR:  "bar"

  $ ruby -rNodeDump -e '"foo#{' -e '""}bar"'
  NodeDump V0.9

  NODE_NEWLINE:  [-e:1]
    NODE_STR:  "foobar"

This optimization is limited to the case #{} ends with a
literal string (and preceding literals without any side
effects)

-- 
Nobu Nakada