Action dispatch for a combat class

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My problem is that I have a piece of code logic that I’m having trouble fitting into an OO approach, and I was looking for design patterns so that the following code would no longer rely on the ugly

if class is of type A do X else do Y

In Python, we can say I have three “fighting method” classes, class Fight, class Manoeuvre, and class Dodge.

I also have a control class that takes two inputs, attackMode and defendMode. The inputs will always be objects whose classes extend from or are of one of the above three.

The piece of script causing issue is as follows:

from random import Random

# Following are example "Action" objects which are to be compared
# For results

class Action:
    "Base Action all others inherit from"
    __random = Random()

    def __init__(self): = 100 

    def getSuccess(cls):
        return cls.__random.randint(-2,3)

class Dodge(Action):
    def __init__(self):
       super(Dodge, self).__init__() 
class Attack(Action):
    def __init__(self):
        super(Attack, self).__init__() 

    def performActionOn(self, subject, sucessLevel=0):
        damage = 5 if successLevel > 1 else 3 -= damage

class Manoeuvre(Action):
    def __init__(self):
        super(Manoeuvre, self).__init__() 

    def performActionOn(self, subject, successLevel=0):

# Following is the results configuration

class CombatControl:
    def fight(self, actionAttack, actionDefend):

        if isinstance(actionDefend, Dodge):
            __attackDodge(actionAttack, actionDefend)
            __attackAttack(actionAttack, actionDefend) 

    def __attackAttack(self, attack, defend):
        " Defender Attacks back
        resultAttack = attack.getSuccess()
        resultDefend = defend.getSuccess()

        # Both failed. No action.
        if resultAttack < 0 and resultDefend < 0: 
        # Attack wins or draw
        elif resultAttack >= resultDefend:
            attack.performActionOn(defend, successLevel=resultAttack)
        # Defend wins
            # Does not get damage bonus

    def __attackDodge(self, attack, defend):
        " Defender is dodging
        resultAttack = attack.getSuccess()
        resultDefend = defend.getSuccess()

        if resultAttack > resultDefend:
            attack.performActionOn(actionAttack, successLevel=resultAttack)

As you can see in the final case, there’s a bit of jiggery-pokery going on where resolution is based upon the type of class. This is undesired.

Ideally I’d want a solution which would allow for something more polymorphic. The structure can change however required if it leads to an elegant solution, as long as the results are the same.


The first thing that came to mind was further encapsulation of the fight mechanics. One thing I did have to change was how success was handled; now it’s a member of each action subclass and is given a new value each time Controller.fight is called.

The other part necessary to this approach was the implementation of a action mode (offensive or defensive) so that actions like Dodge would know what to do.

import random


class Action(object):

    def __init__(self):
        super(Action, self).__init__() = 100
        self.success = 0

    def nextSuccess(self):
        self.success = random.randint(-2, 3)

    def performOn(self, subject, success):

class Dodge(Action):

    def __init__(self):
        super(Dodge, self).__init__()

    def performOn(self, subject):
        if mode == DEFENSIVE and subject.success > self.success:
            subject.performOn(subject, success=subject.success)

class Attack(Action):

    def __init__(self):
        super(Attack, self).__init__()

    def performOn(self, subject, mode):
        if self.success < 0 and subject.success < 0:
        if mode == OFFENSIVE and self.success >= subject.success:
   -= 5 if success > 1 else 3
        elif mode == DEFENSIVE and self.success > subject.success:
   -= 3

class Manoeuvre(Action):

    def __init__(self):
        super(Attack, self).__init__()

class Controller:

    def fight(offense, defense):
        offensive = offense.nextSuccess()
        defensive = defense.nextSuccess()
        offense.performOn(defense, OFFENSIVE)
        defense.performOn(offense, DEFENSIVE)

As far as I can tell this does what the original script did. If there are any tweaks that need to be made, let me know!

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