From: Austin Ziegler <halostatue@...>
Date: 2006-08-15T22:07:34+09:00
Subject: Re: Trouble parsing against a hash

On 8/15/06, Peter Bailey <pbailey@bna.com> wrote:
> Thanks, James. Sorry 'bout Ruby. I don't understand why my pound sign is
> a comment starter there, but, it's not prior to that in the same line.
> Isn't that a legitimate pointer to a variable, #{psfile} ?

No. There's no such thing as a pointer to a variable in Ruby; Ruby
variables don't work that way (thank ghu). The construct #{var} is
used for interpolation, but only in regular expression and quoted
string constructs. That means it can be used with %r{#{var}},
/#{var}/, "#{var}", %Q{#{var}}, %W{#{var}}, and heredocs with
interpolation (<<-"EOS" instead of <<-'EOS').

The #{} interpolation does not even have to be a variable. I could do:

  puts "2 + 2 = #{2 + 2}"

Any legal expression may be in the interpolation, but it may cause
your syntax highlighting routines in your editor some grief if you get
too complex there. Some things do not need the braces, such as global
variables (#$LOAD_PATH) or instance variables (#@inst_var). When
you're not in an interpolative mode, if you use the #{} (or #$ or #@)
you will simply get a commented rest of the line.

-austin
-- 
Austin Ziegler * halostatue@gmail.com * http://www.halostatue.ca/
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               * austin@zieglers.ca