A little Hash goodness

Some quick refactoring this weekend had me throwing together some tidbits.

module Enumerable

  # return Hash of enumeration to yielded values
  def collect_hash hash={}
    inject(hash) {|h,e| h[e] = block_given? ? yield(e) : nil; h }
  end

  # return Hash of enumeration to non-nil yielded values
  def select_hash hash={}, &block
    collect_hash(hash,&block).compact
  end

end


class Hash

  # return Hash with nil values removed
  def compact
    delete_if {|k,v| !v }
  end
  
  # array-style push of key-values
  def <<(hash={})
    merge! hash
  end

end

Yes, I know they've been done before, but they're quick one-liners and let me eliminate a lot of code. And as we all know, the easy code to maintain is the code you delete.