Is it possible to programmatically set instance attributes?

Question

Suppose I want to initialize 50 variables in a Python class. I'd like to do this by loading a dict where each key/value pair corresponds to a self.key = value statement, which are all initialized to None by default.

The code I have right now is:

    def load_values(self, values):
        for k, v in values.iteritems():  
            if k in self.__dict__.keys(): # if the key in the dict matches a previously
                                          # initialized attribute
                self.k = v

This doesn't work because Python thinks k is the name of an attribute, which it is not. How can I make this work? I am running Python 2.7.

What's wrong with using that dictionary as a `variable:value` pairing in your code? — MooingRawr, Jul 31 '17 at 15:43
@mgilson Great, that's exactly what I was looking for. MooingRawr, I'm not sure I understand what you mean. — adamcircle, Jul 31 '17 at 15:46
He means: you could `self.values = values`. Then you only have one more indirection, but at least you know which values come from `values` and there are no conflicts with existing attributes. — Jean-François Fabre, Jul 31 '17 at 15:48
BTW you don't want to set class variables, you want to set instance variables. — Jean-François Fabre, Jul 31 '17 at 15:49

Arount · Accepted Answer · 2017-07-31T21:49:41.730

3

I would use **kwargs and setattr:

class Foo(object):

    def load_values(self, **kwargs):
        for key, value in kwargs.iteritems():
            setattr(self, key, value)


foo = Foo()
foo.load_values(egg='bacon', sausages='spam')
# or
foo.load_values(**{'egg': 'bacon', 'sausages': 'spam'})

print(foo.egg) # bacon
print(foo.sausages) # spam

edited Jul 31 '17 at 21:49

answered Jul 31 '17 at 15:55

Arount

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Is it possible to programmatically set instance attributes?

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