method getattr is not inherited from parent class

Question

Trying to subclass mechanize.Browser class:

from mechanize import Browser

class LLManager(Browser, object):
    IS_AUTHORIZED = False
    def __init__(self, login = "", passw = "", *args, **kwargs):
        super(LLManager, self).__init__(*args, **kwargs)
        self.set_handle_robots(False)

But when I make something like this:

lm["Widget[LinksList]_link_1_title"] = anc

then I get an error:

Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    lm["Widget[LinksList]_link_1_title"] = anc
TypeError: 'LLManager' object does not support item assignment

Browser class have overridden method __getattr__ as shown:

def __getattr__(self, name):
    # pass through _form.HTMLForm methods and attributes
    form = self.__dict__.get("form")
    if form is None:
        raise AttributeError(
            "%s instance has no attribute %s (perhaps you forgot to "
            ".select_form()?)" % (self.__class__, name))
    return getattr(form, name)

Why my class or instance don't get this method as in parent class?

score 1 · Answer 1 · answered Feb 03 '11 at 15:19

1

You need to override __setattr__ to support assignment in this fashion. __getattr__ is only for retrieval

answered Feb 03 '11 at 15:19

Daniel DiPaolo

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Browser class have no `__setattr__` methods. – Крайст Feb 03 '11 at 15:21
That's fine, you can create your own if you want. But this may be a clue that you may not *want* to do that because there's probably a good reason they only have one and not the other. – Daniel DiPaolo Feb 03 '11 at 15:22
What if I want same behaviour as in the parent class? I simply write: `br = Browser(); ...; br["some_input_name"] = "Blah..";` and it works finely for me. – Крайст Feb 03 '11 at 15:28
Pardon.. As **Rosh Oxymoron** said, my target methods are named `__getitem__` and `__setitem__`. – Крайст Feb 03 '11 at 15:38

score 1 · Answer 2 · answered Feb 03 '11 at 15:23

There's difference between items and attributes. Items are accessed using ob[item], while attributes are accessed using ob.item. The methods that define item assignment are __getitem__ and __setitem__, and the second is required if you're going to set items, not only access them. The methods __getattr__, __setattr__ and __getattribute__ deal with attributes, and don't help you here, and besides, the last two should be avoided because they complicate the creation of your class too much.

Oh, sorry.. I knew it but forgot. Does these methods inherits to my class? — Крайст, Feb 03 '11 at 15:32

score 1 · Accepted Answer · answered May 12 '11 at 19:31

Don't inherit from object, mechanize.Browser doesn't use new style classes. This should work as expected.

from mechanize import Browser

class LLManager(Browser):
    IS_AUTHORIZED = False
    def __init__(self, login = "", passw = "", *args, **kwargs):
        mechanize.Browser.__init__(self, *args, **kwargs)
        self.set_handle_robots(False)

method __getattr__ is not inherited from parent class

3 Answers3

method getattr is not inherited from parent class