Hal E. Fulton wrote:

> Maybe I'm overlooking something obvious,
> or maybe it's not possible.
> 
> We all know how convenient string interpolation
> can be: msg = "myval = #{myval}"
> 
> Is there a way to perform interpolation on
> an arbitrary string? For example, if the
> above string were read in from a file?

Unless I'm completely misunderstanding your point, what about using 
eval()? For example, given the Ruby script:

     a = 2
     b = 3

     IO.foreach("commands.txt") do |cmd|
       eval(cmd)
     end

     puts $astr
     puts $bstr

and the text file (commands.txt):

     $astr = "The value of a = #{a}"
     $bstr = "The value of b = #{b}"

I get the result:

     The value of a = 2
     The value of b = 3

Hope this helps,

Lyle