Loop over all variables in class that acts like enum

Question

I have a class that acts like an enum. I want to loop over his variables (enum's values)

class Demos(object):
    class DemoType(object):
        def __init__(self, name):
            self.name = name

        def __repr__(self):
            return self.name

    VARIABLE1 = DemoType("Car")
    VARIABLE2 = DemoType("Bus")
    VARIABLE3 = DemoType("Example")
    VARIABLE4 = DemoType("Example2")

I thought about using Role.__dict__, or vars(Role), but they contain not only the variables, but also the RoleType class and other attributes like __module__. __doc__ and more...

I also want it to be represented like this, mainly because it will add more variables to DemoType. variables other than name, So please try to find an answer this way.

If you want to use an enum and you can upgrade to Python 3.4 then that has them in the standard library. — rlms, Nov 01 '13 at 18:15
http://stackoverflow.com/questions/108523/how-should-i-best-emulate-and-or-avoid-enums-in-python?rq=1 has some good answers. — rlms, Nov 01 '13 at 18:17
possible duplicate of [How can I represent an 'enum' in Python?](http://stackoverflow.com/questions/36932/how-can-i-represent-an-enum-in-python) — thegrinner, Nov 01 '13 at 18:18
Im not sure, because its not a question of how to represent an `enum`, It is about how to iterate over his values — Weiner Nir, Nov 01 '13 at 18:20
I think the answer is to use a different way to represent an `enum`. — rlms, Nov 01 '13 at 18:24

score 1 · Answer 1 · answered Nov 01 '13 at 19:39

1

Rather than reinvent an enum type, it would be better to use Python's Enum type (which has also been backported). Then your code could look like

class Demos(Enum):
    VARIABLE1 = "Car"
    VARIABLE2 = "Bus"
    VARIABLE3 = "Example"
    VARIABLE4 = "Example2"


--> for variable in Demos:
...    print variable

answered Nov 01 '13 at 19:39

Ethan Furman

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Can you use this method and add more to a variable? Like, doing `VARIABLE1`, and add name `Car`, and a description `"A type of vehicle with 4 wheels"`? – Weiner Nir Nov 01 '13 at 23:42
1

@Nirock: Yes, the new `Enum` type is very powerful. Check out [this answer](http://stackoverflow.com/a/19330461/208880) for an `AutoEnum` recipe that easily supports docstrings. – Ethan Furman Nov 02 '13 at 00:29
=\, I need more than that. My Enum represents `TF2 Roles`. So its like `Demoman`, `Soldier`, `Scout`, `Medic`. What I need is to add a value of max_players, for each role. Thats why I use this pattern: http://stackoverflow.com/questions/19542862/how-to-represent-enum-with-functions-in-python – Weiner Nir Nov 02 '13 at 09:06
1

@Nirock: Why don't you ask a new question, `How do I use Python's new Enum for ...`, list a bunch of the attributes and methods that you need/want, and then someone can help with that? – Ethan Furman Nov 02 '13 at 20:43

score 0 · Answer 2 · edited May 23 '17 at 11:59

0

I found the answer, And its not a duplicate of How can I represent an 'Enum' in Python? at all. The answer is to create the following list by the following list comprehensive:

variables = [attr for attr in dir(Demos()) if not attr.startswith("__") and not callable(attr)]
print variables

I can also create a function to do that for me this way:

class Demos(object):
    class DemoType(object):
        def __init__(self, name):
            self.name = name

        def __repr__(self):
            return self.name

    @classmethod
    def get_variables(cls):
        return [getattr(cls, attr) for attr in dir(cls) if not callable(getattr(cls, attr)) and not attr.startswith("__")]

    VARIABLE1 = DemoType("Car")
    VARIABLE2 = DemoType("Bus")
    VARIABLE3 = DemoType("Example")
    VARIABLE4 = DemoType("Example2")


for variable in Demos.get_variables():
    print variable

edited May 23 '17 at 11:59

Community

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answered Nov 01 '13 at 18:28

Weiner Nir

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this should probably be a classmethod instead of an instance method – newtover Nov 01 '13 at 18:40
`class method` or `static method` for this case? – Weiner Nir Nov 01 '13 at 18:41
`classmethod`, since you will need access to the members of the class, I think – newtover Nov 01 '13 at 18:43
ok, a little research told me you are right. I will fix it right now. – Weiner Nir Nov 01 '13 at 18:45
@newtover Because nobody but you active in my question, I have to ask you personally if you have any idea to improve the answer? – Weiner Nir Nov 01 '13 at 18:47
For me it's too verbose. I would not use it, but it all depends on the ways you are going to use it. – newtover Nov 01 '13 at 19:04
You should name the method `__iter__` and it should be a generator. That way you can just iterate over the object rather than having to call a method. – kindall Nov 01 '13 at 19:05
@kindall `__iter__` is a magic method in the class of the iterated object -> metaclass. but a generator would be ok. @Nirock One can use `cls.__dict__` instead of `dir`. – User Nov 01 '13 at 19:11
@kindall, __iter__ can not be classmethod. – newtover Nov 01 '13 at 19:23
Yeah, you'd need to use a metaclass I guess. Or, you know, instantiate your classes... :-) – kindall Nov 01 '13 at 19:25

Loop over all variables in class that acts like enum

2 Answers2