class Build::Files::Path

def initialize(full_path, root = nil, relative_path = nil)

Both paths must be full absolute paths, and path must have root as an prefix. 
def initialize(full_path, root = nil, relative_path = nil)
	# This is the object identity:
	@full_path = full_path
	
	if root
		@root = root
		@relative_path = relative_path
	else
		# Effectively dirname and basename:
		@root, _, @relative_path = full_path.rpartition(File::SEPARATOR)
	end
end