Ruby 1.9 regex as a hash key

Question

I am trying this example myhash = {/(\\d+)/ => \"hello\"} with ruby 1.9.2p136 (2010-12-25) [i386-mingw32].
It doesn\'t work as exp

Answer 1

It never occurred to me to use a regex as a hash key. I'm honestly not sure if that should work, nor exactly how it would work if it should.

In any case, two thoughts:

1. In your attempts to lookup the item, you use hash, but the hash is named myhash.

2. If I play around with it, I get these results:

   hektor ~ ❯❯ irb
   >> myhash = {/(\d+)/ => "hello"}
   => {/(\d+)/=>"hello"} 
   >> myhash['2222']
   => nil 
   >> myhash[2222]
   => nil 
   >> myhash[/(\d+)/]
   => "hello" 
   

This is using Ruby 1.9.2-p180.

Ok, checked and here's what works:

myhash = {/foo/ => "hello"}
myhash[/foo/] # => "hello"

The lookup is on the key, and the key is a regex, not one of the many potential matches of that regex.