Unix-like Command style

Contribution by Vincent Le Geoff (vlgeoff), 2017

This module contains a command class with an alternate syntax parser implementing Unix-style command syntax in-game. This means --options, positional arguments and stuff like -n 10. It might not the best syntax for the average player but can be really useful for builders when they need to have a single command do many things with many options. It uses the ArgumentParser from Python’s standard library under the hood.

Installation

To use, inherit UnixCommand from this module from your own commands. You need to override two methods:

• The init_parser method, which adds options to the parser. Note that you should normally not override the normal parse method when inheriting from UnixCommand.

• The func method, called to execute the command once parsed (like any Command).

Here’s a short example:

from evennia.contrib.base_systems.unixcommand import UnixCommand


class CmdPlant(UnixCommand):

    '''
    Plant a tree or plant.

    This command is used to plant something in the room you are in.

    Examples:
      plant orange -a 8
      plant strawberry --hidden
      plant potato --hidden --age 5

    '''

    key = "plant"

    def init_parser(self):
        "Add the arguments to the parser."
        # 'self.parser' inherits `argparse.ArgumentParser`
        self.parser.add_argument("key",
                help="the key of the plant to be planted here")
        self.parser.add_argument("-a", "--age", type=int,
                default=1, help="the age of the plant to be planted")
        self.parser.add_argument("--hidden", action="store_true",
                help="should the newly-planted plant be hidden to players?")

    def func(self):
        "func is called only if the parser succeeded."
        # 'self.opts' contains the parsed options
        key = self.opts.key
        age = self.opts.age
        hidden = self.opts.hidden
        self.msg("Going to plant '{}', age={}, hidden={}.".format(
                key, age, hidden))

To see the full power of argparse and the types of supported options, visit the documentation of argparse.

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