Default Hash Argument As Proc

hash_default_proc.rb

example = Hash.new(Proc.new { raise Exception.new "Named action doesn't exist" }
example[:do_something_cool] = Proc.new { puts "I just did something cool!" }
example[:do_something_else_cool] = Proc.new { puts "I did another cool thing!" }

example[:do_something_cool].call
# => "I just did something cool!"

example[:do_something_else_cool].call
# => "I did another cool thing!"

example[:do_one_last_cool_thing].call
# => Exception: Named action doesn't exist

take_it_further_with_a_block.rb

example = Hash.new do |hash, key|
  Proc.new do |name|
    raise Exepction.new "#{name} can't #{key.to_s.gsub("_", " ")}"
  end
end

example[:did_something_cool] = Proc.new { |name| puts "#{name} just did something cool!" }
example[:did_something_else_cool] = Proc.new { |name| puts "#{name} did another cool thing!" }

example[:do_something_cool].call("John")
# => "John just did something cool!"

example[:do_something_else_cool].call("John")
# => "John did another cool thing!"

example[:do_one_last_cool_thing].call("Marvin")
# => Exception: Marvin can't do one last cool thing