From: Sascha Ebach <se@...>
Date: 2005-08-05T09:15:03+09:00
Subject: Need help with with Binding.of_caller

Hi,

(hoping that Florian is reading)

I am just in the process of patching ri18n[1] interpolation 
functionality. Here is what I a trying to do:

ri18n offers a way to interpolate strings. This is for translation 
purposes. The current version of the interpolation method looks like this:

class String
   def interpolate(caller)
     caller.instance_eval('"' << self.gsub('"', '\"') << '"')
   end
...
end

original version is here:

http://svn.berlios.de/viewcvs/ri18n/trunk/lib/ri18n/standard_exts.rb?view=markup

This will correctly interpolate the following:

@color = 'red'
_i('#{@color} whine')

but not this:

color = 'red'
_i('#{color} whine')

So I thought I might try to use the Binding.of_caller technique. I came 
as far as this:

class String
   def interpolate(caller) # the param is not needed anymore
     Binding.of_caller do |binding|
       eval('"' << self.gsub('"', '\"') << '"', binding)
     end
   end
...
end

which will do exactly the opposite. Now I am able to eval local 
variables, but not the instance vars.

this doesn't work:

@color = 'red'
_i('#{@color} whine')

but this does:

color = 'red'
_i('#{color} whine')

What do I need to do to capture the whole environment of the originating 
_i() call. Is it at all possible?

Sascha Ebach

[1] http://ri18n.berlios.de/