Question

I came across the __getattr__ built-in and was wondering when it would be used. I had a hard time thinking of a practical use from the documentation
http://docs.python.org/reference/datamodel.html#. What would be an actual example of how it could be used and useful in code?

Answer 1

One example is to use object notation with dictionaries. For example, consider a dictionary

myDict = {'value': 1}

Typically in Python one accesses the ‘value’ variable as

myDict['value']

which will print 1 at the Python interpreter. However, one may wish to use the myDict.value notation. This may be achieved by using the following class:

class DictAsMember(dict):
    def __getattr__(self, name):
        value = self[name]
        if isinstance(value, dict):
            value = DictAsMember(value)
        return value

my_dict = DictAsMember()
my_dict['property'] = {'sub_property': 1}

print(my_dict.property.sub_property) # 1 will be printed