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Python Object-Oriented Python Advanced Objects Subclassing Built-ins

Posted by daniel steinberg
daniel steinberg
14,651 Points

__getattribute__ question

I am trying to understand Kenneth discuss getattribute.

code:

class JavaScriptObject(dict):
    def __getattribute__(self, item):
        try:
            return self[item]
        except KeyError:
            return super().__getattribute__(item)

In the following code he says the 

except KeyError:
            return super().__getattribute__(item)

will look for an attribute with dot notation in the original dict

What would be an example of an an "attribute with dot notation in the original dict"

that would not be found in the 'try' section but would be found in the 'except' section?

He does not give an example unfortunately.

Thanks

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,461 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,461 Points

Good question. Python uses the __getattribute__ method to get methods as well as "regular" attributes.

>>> class JavaScriptObject(dict):
...    def __getatt... ribute__(self, item):
...       try:
...          return self[item]
...       except KeyError:
...          print("in mydict.__getattribute__ for", str(item))
...          return super().__getattribute__(item)
...
>>> j = JavaScriptObject()
>>> j.items()
in mydict.__getattribute__ for items
dict_items([])
>>> j['foo'] = 'bar'
>>> j.foo
'bar'
>>> j.keys()
in mydict.__getattribute__ for keys
dict_keys(['foo'])

Post back if you need more help. Good luck!!