# Standard class for error messages
class Error
	# A short human-readable error message.
	#
	# This message is short and informative and could be displayed on the console, a dialog-box
	# or written in a log file.
	#
	# Message should be explicative, autonomous and do not depend on contextual information.
	#
	# Eg. instead of "Fatal error: cannot open file",
	# something like "File error, cannot open /some/path/document.ext, file not found." is preferred,
	# where the message is informative as it, and the severity of the error is not assumed:
	# while fatal for the library, it could be something benign for the program.
	var message: String

	# An original error that caused the creation of this error, if any.
	#
	# This is used to chain errors and track the implication of various sub-systems for a given error.
	#
	# When displaying an error the end user, causes can be recursively displayed.
	var cause: nullable Error = null is writable

	redef fun to_s do return message
end