From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-07-16T23:19:31+09:00
Subject: Re: delaying string evaluation

On Sat, 16 Jul 2005, Navindra Umanee wrote:

> Hi,
>
> I would like to partially expand a string and then further expand it
> later on when more information is available.  I am currently using
> string interpolation with a reeval method suggested by Bill Kelly.
>
> class String
>  def reeval(b = TOPLEVEL_BINDING)
>    eval("<<END_REEVAL\n" + self + "\nEND_REEVAL\n", b).chomp!
>  end
> end
>
> This lets me do stuff like this:
>
> expanded = "one"
> delayed = "two"
>
> s = "#{expanded} \#{delayed}"       # => "one #{delayed}"
> s = s.reeval(binding)               # => "one two"

why not make up a mini interpolator?

   ~ > cat a.rb
   class String
     def expand! h = {}
       gsub!(%r/:\w+/o){|k| h[k.delete(':').intern] || k}
     end
     def expand(*a, &b)
       dup.expand!(*a, &b); self
     end
   end

   s = '<:expanded> - <:delayed>'

   s.expand! :expanded => 'one'
   puts s

   s.expand! :delayed => 'two'
   puts s

   ~ > ruby a.rb
   <one> - <:delayed>
   <one> - <two>

cheers.

-a
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