From: "SHULTZ,BARRY (HP-Israel,ex1)" <barry_shultz@...>
Date: 2002-02-19T01:19:50+09:00
Subject: RE: hash question

Hi,

> hello
> I read in the pickaxe book that I can also use a Regexp as a hash key
> 
> lets says I have this code:
> 
> hash = Hash.new
> hash["bird"] = "vogel"
> hash["lynx"] = "luchs"
> hash["snake"] = "schlange"
> 
> hash.each {|k,v|
>   print k, " -> ", v, "\n" if k =~ /^b/
> }
> 
> the output is of course:
> bird -> vogel
> 
> 
> but I like to use the regexp /^b/ before the block
> something like
> 
> hash[/^b].each {|k,v|
>   print k, " -> ", v, "\n" if k =~ /^b/
> }
> 
> but this does not work. I thought that if this would work
> it could be faster because the block is only called 
> for the keys which macht the regexp.
> 
> any ideas how this could be done.

You could do this:

hash.keys.grep(/^b/){|key| print key, " -> ",hash[key],"\n"}

Regards,
Barry