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

Are you looking for this behaviour?

myhash = Hash.new{|h,k| h[k] = 'hello' if k =~ /(\d+)/}

p myhash['aaa'] #=> nil
p myhash #=> {}
p myhash['1234'] #=>" hello"
p myhash #=> {"1234"=>"hello"}