# Returns a version string (example: "1.5.6b42a7c") from an annotation `version(1, 5, git_revision)`.
	#
	# The user can enter as many fields as needed. The call to `git_revision` will be replaced by the short
	# revision number. If the working tree is dirty, it will append another field with "d" for dirty.
	private fun as_version(modelbuilder: ModelBuilder): String
	do
		var version_fields = new Array[Object]

		var args = n_args
		if args.length < 1 then
			modelbuilder.error(self, "Syntax Error: `{name}` expects at least one argument.")
			return ""
		else
			for arg in args do
				var value
				value = arg.as_int
				if value != null then
					version_fields.add value
					continue
				end

				value = arg.as_string
				if value != null then
					version_fields.add value
				end

				value = arg.as_id
				if value == "git_revision" then
					# Get Git short revision
					var proc = new ProcessReader("git", "rev-parse", "--short", "HEAD")
					proc.wait
					if proc.status != 0 then
						# Fallback if this is not a git repository or git bins are missing
						version_fields.add "0"
						modelbuilder.warning(self, "git_revision", "Warning: `git_revision` used outside of a git repository or git binaries not available")
						continue
					end

					var lines = proc.read_all
					var revision = lines.split("\n").first

					# Is it dirty?
					# If not, the return of `git diff --shortstat` is an empty line
					proc = new ProcessReader("git", "diff-index", "--quiet", "HEAD")
					proc.wait
					var dirty = proc.status != 0
					if dirty then revision += ".d"

					version_fields.add revision
					continue
				end

				var format_error = "Syntax Error: `{name}` expects its arguments to be of type Int or a call to `git_revision`."
				modelbuilder.error(self, format_error)
				return ""
			end
		end

		return version_fields.join(".")
	end