Ruby Hash monkey-patch methods relating to the hash’s default

hash_default_setting.rb

# encoding: utf-8

class Hash
	def with_new_default(*hash_new_args, &hash_new_block)
		empty_defaulting_hash = Hash.new(*hash_new_args, &hash_new_block)
		
		# using #merge; #replace would also replace the default value
		return empty_defaulting_hash.merge(self)
	end
	
	def with_default(*args, &block)
		# like with_new_default, but requires an argument –
		#  it wouldn’t make sense to write `{a: 1}.with_default`
		# TODO implement
	end
end

hash_default_setting_example_usage.rb

{a: 1, b: 2}.with_default(:missing)
{a: 1, b: 2}.with_default{Time.now}
my_hash_with_a_bad_default.with_default(:missing)
my_hash_with_a_bad_default.with_default{Time.now}
my_hash_with_a_bad_default.with_new_default
my_hash_with_a_bad_default.with_new_default(:missing)
my_hash_with_a_bad_default.with_new_default{Time.now}

hash_default_type.rb

# encoding: utf-8

class Hash
	# These methods supplement Hash#default and #default_proc when exploring unfamiliar hashes.
	
	def default_is_proc?
		! default_proc.nil?
		# Checking #default wouldn’t help; it could be anything.
		# But #default_proc is either a Proc or nil.
	end
	
	def default_type
		if default_is_proc?
			:proc
		else
			:value
		end
	end
end

hash_default_type_example_usage.rb

class Hash
	def use_default_default!
		default_hash = {}
		if default_hash.default_is_proc?
			self.default_proc = default_hash.default_proc
		else
			self.default = default_hash.default
		end
	end
end