How to assign hash['a']['b']= 'c' if hash['a'] doesn't exist?

Question

Is there any way simpler than

if hash.key?(\'a\')
  hash[\'a\'][\'b\'] = \'c\' 
else  
  hash[\'a\'] = {}
  hash[\'a\'][\'b\'] = \'c\' 
end

Answer 1

If you create hash as the following, with default value of a new (identically default-valued) hash: (thanks to Phrogz for the correction; I had the syntax wrong)

hash = Hash.new{ |h,k| h[k] = Hash.new(&h.default_proc) }

Then you can do

hash["a"]["b"] = "c"

without any additional code.