Source code for evennia.contrib.slow_exit

"""
Slow Exit typeclass

Contribution - Griatch 2014


This is an example of an Exit-type that delays its traversal.This
simulates slow movement, common in many different types of games. The
contrib also contains two commands, CmdSetSpeed and CmdStop for changing
the movement speed and abort an ongoing traversal, respectively.

To try out an exit of this type, you could connect two existing rooms
using something like this:

@open north:contrib.slow_exit.SlowExit = <destination>


Installation:

To make this your new default exit, modify mygame/typeclasses/exits.py
to import this module and change the default Exit class to inherit
from SlowExit instead.

To get the ability to change your speed and abort your movement,
simply import and add CmdSetSpeed and CmdStop from this module to your
default cmdset (see tutorials on how to do this if you are unsure).

Notes:

This implementation is efficient but not persistent; so incomplete
movement will be lost in a server reload. This is acceptable for most
game types - to simulate longer travel times (more than the couple of
seconds assumed here), a more persistent variant using Scripts or the
TickerHandler might be better.

"""

from evennia import DefaultExit, utils, Command

MOVE_DELAY = {"stroll": 6, "walk": 4, "run": 2, "sprint": 1}


class SlowExit(DefaultExit):
    """
    This overloads the way moving happens.
    """

    def at_traverse(self, traversing_object, target_location):
        """
        Implements the actual traversal, using utils.delay to delay the move_to.
        """

        # if the traverser has an Attribute move_speed, use that,
        # otherwise default to "walk" speed
        move_speed = traversing_object.db.move_speed or "walk"
        move_delay = MOVE_DELAY.get(move_speed, 4)

        def move_callback():
            "This callback will be called by utils.delay after move_delay seconds."
            source_location = traversing_object.location
            if traversing_object.move_to(target_location):
                self.at_after_traverse(traversing_object, source_location)
            else:
                if self.db.err_traverse:
                    # if exit has a better error message, let's use it.
                    self.caller.msg(self.db.err_traverse)
                else:
                    # No shorthand error message. Call hook.
                    self.at_failed_traverse(traversing_object)

        traversing_object.msg("You start moving %s at a %s." % (self.key, move_speed))
        # create a delayed movement
        t = utils.delay(move_delay, move_callback)
        # we store the deferred on the character, this will allow us
        # to abort the movement. We must use an ndb here since
        # deferreds cannot be pickled.
        traversing_object.ndb.currently_moving = t


#
# set speed - command
#

SPEED_DESCS = {"stroll": "strolling", "walk": "walking", "run": "running", "sprint": "sprinting"}


class CmdSetSpeed(Command):
    """
    set your movement speed

    Usage:
      setspeed stroll|walk|run|sprint

    This will set your movement speed, determining how long time
    it takes to traverse exits. If no speed is set, 'walk' speed
    is assumed.
    """

    key = "setspeed"

    def func(self):
        """
        Simply sets an Attribute used by the SlowExit above.
        """
        speed = self.args.lower().strip()
        if speed not in SPEED_DESCS:
            self.caller.msg("Usage: setspeed stroll||walk||run||sprint")
        elif self.caller.db.move_speed == speed:
            self.caller.msg("You are already %s." % SPEED_DESCS[speed])
        else:
            self.caller.db.move_speed = speed
            self.caller.msg("You are now %s." % SPEED_DESCS[speed])


#
# stop moving - command
#


class CmdStop(Command):
    """
    stop moving

    Usage:
      stop

    Stops the current movement, if any.
    """

    key = "stop"

    def func(self):
        """
        This is a very simple command, using the
        stored deferred from the exit traversal above.
        """
        currently_moving = self.caller.ndb.currently_moving
        if currently_moving and not currently_moving.called:
            currently_moving.cancel()
            self.caller.msg("You stop moving.")
            for observer in self.caller.location.contents_get(self.caller):
                observer.msg("%s stops." % self.caller.get_display_name(observer))
        else:
            self.caller.msg("You are not moving.")