Python Class For Homogenous Sets Of Objects

I frequently find myself creating homogeneous sets of objects, which i usually store in a dict or list dictionaries. a,b,c = MyClass(...), MyClass(...), MyClass(...) my_set

Solution 1:

You are look for special methods of classes. Have a look __getattr__ and __getitem__. You can write your own class. Its instances of this class can have a, b and c as attributes and can do what you describe.

Some thing like this might do part of what you like to do:

classDictCollcetion(object):
    def__init__(self, dict_):
        self.dict = dict_
    def__getattr__(self, name):
        return {k: k.name for k in self.dict}
    def__getitem__(self, key):
        return {k: k.key for k in self.dict}

Solution 2:

I've run into cases where I have manipulated big lists of dictionaries or objects, much like you have. Often those objects are pulled out of a database and populated via an ORM, but I've done it with CSV files as well.

I am not sure that my needs are frequent/common enough that I would look for a module to give me syntactic sugar for it.

Solution 3:

Have you considered just using sets?

my_set = {myclass(...),myclass(...),myclass(...)}
props = {k.prop for k in my_set}

While you could create a class that does that mapping for you, it's not obvious to me that this makes your code any clearer than sticking with standard mapping constructs.

Solution 4:

Following the suggestion of @mike-muller to override the _getattr__ method i created a class here

https://gist.github.com/arsenovic/5723000