From: MonkeeSage <MonkeeSage@...>
Date: 2008-01-05T22:30:00+09:00
Subject: Re: change the symbol in an interpolated string value?

On Jan 3, 7:15 am, scoot...@hotmail.com wrote:
> > Why do you need a
> > different syntax?
>
> > Regards,
> > Jordan
>
> It's not a dire need, but it would definitely be useful. For example,
> suppose you are constructing a string that generates ruby code. You
> will need a way to tell the parser that #{foobar} is no longer
> intended as a variable placeholder.
>
> You could, of course, change the entire string into an uninterpolated
> string, but that eliminates the ability to specify variables entirely.
>
> Just to let you know this is not an original idea that I cooked up out
> of thin air, see how Python supports this feature in:
>
>    http://www.python.org/dev/peps/pep-0292/
>
> and search for the text:
>
>     define a delimiter character other than '$'
>
> ALTERNATIVE QUESTION:
>
> I've used ERB before, does it enable you to specify alternate syntaxes
> for the variable placeholders? Template::Toolkit (as an example) does
> allow this, if you want more details on what I am asking about, take a
> look at:
>
>    http://template-toolkit.org/docs/manual/Syntax.html
>
> Thanks for your responses so far.

Hmm...what about using %q{} or escaping "#"? You can emulate the
python Template class (which I have never actually used in live python
code, since % has always worked for my needs); but since it will be
slower (benchmark Template.substitute against % in python), and you
can do the same thing in different ways, it seems pointless to me.
But, for completeness, here is an example:

class Template < String
  def substitute(context=nil)
    if /@\{(.+?)\}/ =~ self
      self.gsub("@{#{$1}}", eval($1, context))
    else
      self
    end
  end
end

blah = "foo"
t = Template.new("Hello @{blah}").substitute(binding)
p t # => "Hello foo"
t = Template.new("Hello world").substitute
p t # => "Hello world"

Regards,
Jordan