Instantiate classes in python from list of strings

Question

I have found answers on stackoverflow that seem to be getting at my question, but I can't find something that I have been able to get to work. I have a really big list of strings like this:

db = ['a','b','c']

And I want to instantiate a class for each string, where unique strings would be the variable names:

a = MyClass()
b = MyClass()
c = MyClass()

I thought to convert the strings to variables, but this doesn't seem advisable from some answers I'm finding here on SO.

What is the best way of going about this?

Just use a dict with the strings as keys and the class instances as values. That's pretty much how Python namespaces work anyway. — Peter DeGlopper
– Peter DeGlopper, Commented Nov 23, 2015 at 23:15
@letsc I have read that in a number of posts, but I'm not sure how to do this. Should the values all be an instantiation of a class with the same variable name? Like this: {'a':x, 'b':x, 'c':x} — The Nightman
– The Nightman, Commented Nov 23, 2015 at 23:17
You want something like instances = dict((k, MyClass()) for k in db). Or a dict comprehension, if you're on at least 2.7: instances = {k: MyClass() for k in db}. — Peter DeGlopper
– Peter DeGlopper, Commented Nov 23, 2015 at 23:25

MaxNoe · Accepted Answer · 2015-11-23 23:56:56Z

1

I do not recommend this

You can add the names to the globals

names = ['a', 'b', 'c']
globals().update({name: MyClass() for name in names})
print(a)

or locals dictionary:

def myfunc():
    names = ['a', 'b', 'c']
    locals().update({name: MyClass() for name in names})
    print(a)

Using a dict

Better would be just to use a dict to store your MyClass-instances:

names = ['a', 'b', 'c']
data = {k: MyClass() for k in names}
print(data['a'])

answered Nov 23, 2015 at 23:56

MaxNoe

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Instantiate classes in python from list of strings

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I do not recommend this

Using a dict

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I do not recommend this

Using a dict

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