initialize a new DummyArray with capacity.

Property definitions

dummy_array $ DummyArray :: defaultinit
	# initialize a new DummyArray with `capacity`.
	init(capacity: Int) is old_style_init do
		_capacity = capacity
		_keys = new NativeArray[Int](capacity)
		_values = new NativeArray[Int](capacity)
	end
lib/dummy_array/dummy_array.nit:82,2--87,4