A little problem with instances[SOLVED]

[DannyGMaster]

I'm trying to make an Elemental Affinity system for use in a battle system, where every character and every skill have their own elemental properties (something like Chrono Cross).

I have some basic knowledge of Python, but it stills doesn't seem enough as this is probably a simple error but I just can't figure out (or remember) a workaround for this.

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init python:
    
    #This is the element class, here I create some attributes for every element.
    # Element resistances, weaknesses, etc. are passed as a list to be able to
    # give an element more than one weakness or resistance.
    class Element(object):
    
        def __init__(self, name, resist=[], weak=[]):
            self.name = name
            self.resist = resist
            self.weak = weak

    #Element instances
    neutral = Element(name='Neutral', resist=[], weak=[]) 
    water = Element(name='Water', resist=[fire], weak=[]) #Bug ocurrs here, because fire isn't defined yet
    fire = Element(name='Fire', resist=[], weak=[water])    
# But if i change the order, the same would occur, as water would not be defined.

I'm missing a step or something, can anybody help?

[xela]

You can use strings instead of Element instances. It's touch to use an instance before it actually exists...

Doesn't look like it's gonna be an issue here, but keep this in mind: https://twitter.com/raymondh/status/822296239156920321

[DannyGMaster]

Thanks, I figures it would be better with strings.

And thanks for warning me of the empty lists, it does look cleaner the way raymond suggests

[Remix]

Also remember that when you do

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reference_name = Element(arguments)

you are instantiating an object with that reference, so anything later in the code that uses that reference is just pointing at that single one instance of the object.

Think of it like making some word docs in one global folder, calling one of them fire.doc (fire.doc = new WordDoc(contents) ) means you cannot have a second fire.doc unless you use a different pointer/name such as fire2.doc. Even if the contents of the .docs are the same, their filenames/references have to be different... so, if something is weak to fire.doc it does not automatically become weak to fire2.doc.
Hope that kind of made sense.

Also, try to think of how and when you will need the objects, it should help you design the class nicely.... e.g. (if you wanted a name and type)
enemy1 = Element('Bob the Firey Enemy', 'fire', ... some data)
friend1 = Element('Drippy the umm drippy watery friend', 'water')

On an aside, you could extend the classes using a base class and children inheriting from that...

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class Element(object):
        def __init__(self, name):
            self.name = name
            self.type = None
            self.resist = []
            self.weak = []

        # this method also appears in any child class based on Element
        # Most methods (functions within classes) will appear in this parent class
        def test_resist(self, attacker_type):
            return attacker_type in self.resist

class FireElement(Element): # Class based on Element 
        def __init__(self, name):
            # This line basically just calls the parent __init__ as though it existed in this object
            # It would set self.name then set up empty .type, .resist and .weak variables
            super(FireElement, self).__init__(name)
            # We can then amend them after we call it to make objects of this class slightly different
            self.type = 'fire'
            self.resist = ['fire', 'lava']
            self.weak = ['water', 'ice']

# then define IceElement, WaterElement... etc

enemy1 = FireElement('Bob the pest')   
resisted = enemy1.test_resist('lava')

Typed on the fly, ergo untested.
Hopefully it gives some ideas for possible options though.

[DannyGMaster]

Wow, @Remix, that could actually be way better, thank you too!