Legal syntax, bug or what?

Ruby
1

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 M.

2

Hi –

On Fri, 1 Sep 2006, Jonathan M. wrote:

When I copy-paste the entire method to a file and run it through Ruby
irb(main):006:2> end
Doesn’t Ruby see the first double-quote as the end of the string?

Any clarification would be greatly appreciated.

Nested #{} are allowed, so this is some kind of irb parsing glitch.
It seems to be the = that’s confusing irb for some reason:

irb(main):002:0> “#{“hello#{}”}”
=> “hello”
irb(main):003:0> “#{“hello=#{}”}”
irb(main):004:0*

I believe it’s causing the second # to be interpreted as introducing a
comment.

David