Fix issue #22 (rule lookup does not count inheritance)

[ivan-kleshnin]

Fix issue https://github.com/apiguy/flask-classy/issues/22

The issue is with cache strictly bound to the class object. Rule lookup doesn't count inheritance correctly.

Then, if you have

class BaseView(FlaskView):
    @route('/delete/<id>')
    def delete(self, id=None):
        pass

class PostsView(BaseView):
    @route('test')  # any route to provide new cache obj instance
    def test(self): # and break behavior
        pass

It generates

Map(...
    <Rule '/posts/<id>' (OPTIONS, DELETE) ...>,
)

While it should generate

Map(...
 <Rule '/delete/<id>' (HEAD, OPTIONS, GET) ...>
)

Diff looks a bit scary but basically i added just 3 lines to deal with inheritance. This fix passes all tests.

I fixed this fragment

if hasattr(cls, "_rule_cache") and name in cls._rule_cache:
    for idx, cached_rule in enumerate(cls._rule_cache[name]):
        ...
elif name in special_methods:
    ...

by wrapping in .mro() lookup loop:

for _cls in cls.mro()[:-1]: # -1 to skip `object` lookup
    if hasattr(_cls, "_rule_cache") and name in _cls._rule_cache:
        for idx, cached_rule in enumerate(_cls._rule_cache[name]):
            ...
        break
else: # no break
    if name in special_methods: # elif -> if
        ... 

I'm not 100% sure about solution. Flask-Classy is kinda tricky ;) I'm sure even less about git though...

[apiguy]

This is great. Let me play with it just a bit and add some tests specifically for it.

[apiguy]

After the Python 3 changes (pretty substantial changes were needed) this will need to be modified. I think the general idea is still the right way to do it though. I'll spend some more time on this tomorrow and hopefully get it out.

[ivan-kleshnin]

Yep, thank you.