Command Design Pattern

commander.py

from functools import partial


class CommandException(Exception):
    def __init__(self, message):
        self.message = message


class Command:
    """
    The Command class encapsulates an action (a function or method) and its arguments.
    It allows the action to be executed later with the execute method.
    """

    def __init__(self, func, *args, **kwargs):
        """
        Initializes a new instance of the Command class.

        :param func: The function or method to be executed.
        :param args: The positional arguments for the function.
        :param kwargs: The keyword arguments for the function.
        """
        self.func = partial(func, *args, **kwargs)

    def execute(self):
        """
        Executes the encapsulated function or method.

        If an exception occurs during execution, it is caught and printed.
        """
        try:
            self.func()
        except Exception as e:
            raise CommandException(e)


class Invoker:
    """
    The Invoker class maintains a list of Command instances.
    It allows all commands to be executed in the order they were added with the execute_commands method.
    """

    def __init__(self):
        """
        Initializes a new instance of the Invoker class.
        """
        self.commands: list[Command] = []

    def add_command(self, command: Command):
        """
        Adds a Command instance to the list of commands.

        :param command: The Command instance to be added.
        """
        self.commands.append(command)

    def execute_commands(self):
        """
        Executes all Command instances in the list in the order they were added.
        """
        for command in self.commands:
            try:
                command.execute()
            except CommandException:
                raise