From: Jonathan Maasland <nochoice@...4all.nl>
Date: 2006-09-01T18:03:55+09:00
Subject: Legal syntax, bug or what?

Hi all,

I'm still working on Ripper and during my explorations I came across a 
line of code in mkmf.rb that I can't wrap my head around.

Line 1313
---
    opts = $arg_config.collect {|t, n| "\t#{t}#{"=#{n}" if n}\n"}
---

When I copy-paste the entire method to a file and run it through Ruby 
everything is fine.
However irb doesn't accept the method:
----
irb(main):001:0> def mkmf_failed(path)
irb(main):002:1>   unless $makefile_created or File.exist?("Makefile")
irb(main):003:2>     opts = $arg_config.collect {|t, n| "\t#{t}#{"=#{n}" 
if n}\n"}
irb(main):004:3*     abort "*** #{path} failed ***\n" + FailedMessage + 
opts.join
irb(main):005:3>   end
irb(main):006:2> end
irb(main):007:1>
------
As you can see irb doesn't detect the end of the third line.

After taking the statement apart and simplifying it, it all boils down 
to the following construction:
#{"=#{n}" if n}
inside the ""main"" double-quoted string.

Why does ruby accept this construct while irb doesn't?
Doesn't Ruby see the first double-quote as the end of the string?

Any clarification would be greatly appreciated.

With kind regards
Jonathan Maasland