[MacRuby-devel] Question on Hash performance

[Robert Rice]

I suspect that there is considerably more overhead in creating a Hash  as compared to an Array and that using an Array is more efficient unless the Array will become large. I am wondering about how large the Array would have to be before it becomes more efficient to use a Hash. Consider the following example:

class Test
	def initialize
		@array	= []
		@hash	= {}
	end

	def get_from_hash( key )
		@hash[ key ]
	end

	def set_hash( key, value )
		value.nil? ? @hash.delete( key ) : @hash[ key ] = value
	end

	def get_from_array( key )
		pair = @array.assoc( key )
		pair ? pair.last : nil
	end

	def set_array( key, value )
		pair = @array.assoc( key )
		if pair
			value.nil? ? @array.delete( pair ) : pair[1] = value
			else
			@array << [ key, value ] unless value.nil?
		end
	end

end

Clearly it requires more code to emulate the hash function with an Array, but would it run faster for a small number of keys?

Bob Rice