From: David Alan Black <dblack@...>
Date: 2001-11-21T03:16:18+09:00
Subject: [ruby-talk:25931] Re: Why does #{a} not evaluate when read from file?

[I mailed this answer a while ago but it hasn't shown up on the
list.]


Hello --

The short answer is: because String handling in Ruby is sane :-)

On Wed, 21 Nov 2001, Jim Freeze wrote:

> Hi
> Here I am again.
>
> I have a file with the line '#{a}' in it.
> I would like the variable 'a' to be evaluated
> when printed.

Be careful what you wish for.

  def echo
    print "Type something: "
    s = gets
    puts "You typed: #{s}"
  end

  echo
  Type something: `rm -rf *`

It's actually good that strings remain inert under these conditions,
instead of performing a level of interpolation on themselves.  You can
always do some eval'ing.

(There was some discussion of this fairly recently -- see
ruby-talk:23658.)


David

-- 
David Alan Black
home: dblack@candle.superlink.net
work: blackdav@shu.edu
Web:  http://pirate.shu.edu/~blackdav