Convert dictionary entries into variables

Is there a Pythonic way to assign the values of a dictionary to its keys, in order to convert the dictionary entries into variables? I tried this out:

>>> d = {'a':1, 'b':2}
>>> for key,val in d.items():
        exec('exec(key)=val')
            
        exec(key)=val
                 ^ 
        SyntaxError: invalid syntax

I am certain that the key-value pairs are correct because they were previously defined as variables by me before. I then stored these variables in a dictionary (as key-value pairs) and would like to reuse them in a different function. I could just define them all over again in the new function, but because I may have a dictionary with about 20 entries, I thought there may be a more efficient way of doing this.

Solution 1:

You can do it in a single line with:

>>> d = {'a': 1, 'b': 2}
>>> locals().update(d)
>>> a
1

However, you should be careful with how Python may optimize locals/globals access when using this trick.

Note

I think editing locals() like that is generally a bad idea. If you think globals() is a better alternative, think it twice! :-D

Instead, I would rather always use a namespace.

With Python 3 you can:

>>> from types import SimpleNamespace    
>>> d = {'a': 1, 'b': 2}
>>> n = SimpleNamespace(**d)
>>> n.a
1

If you are stuck with Python 2 or if you need to use some features missing in types.SimpleNamespace, you can also:

>>> from argparse import Namespace    
>>> d = {'a': 1, 'b': 2}
>>> n = Namespace(**d)
>>> n.a
1

If you are not expecting to modify your data, you may as well consider using collections.namedtuple, also available in Python 3.

Solution 2:

This was what I was looking for:

>>> d = {'a':1, 'b':2}
>>> for key,val in d.items():
        exec(key + '=val')

Solution 3:

You already have a perfectly good dictionary. Just use that. If you know what the keys are going to be, and you're absolutely sure this is a reasonable idea, you can do something like

a, b = d['a'], d['b']

but most of the time, you should just use the dictionary. (If using the dictionary is awkward, you are probably not organizing your data well; ask for help reorganizing it.)