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Both Cheetah and ZPT's TALES use a sort of soft sense of traversal. When you call $person.address.city in Cheetah (or person/address/city in TALES) that might be equivalent to person().address().city(), or maybe person['address'].city or person().address()['city'] or any number of combinations.

This is really convenient. You don't have to think too much about what each object is. You are, after all, giving explicit names (address, city), and these names explain just what you are trying to do (different from if it meant person(address)[city]). What's really the difference between a dictionary and an attribute? A property and a method that takes zero arguments?

Part of the justification of this is that both Cheetah and ZPT/TALES are for displaying information. Your template isn't supposed to do anything, it's not supposed to have side-effects. So any methods you call shouldn't matter. And attributes and dictionaries have always been fuzzy -- every object has its __dict__ after all.

But even in spite of these objects, what really is the value of these different kinds of accessors? Does person.address really mean something different than person['address']? And what use is a method object really, do you often want to know what person.address is in addition to person.address()?

I think there are justifications for Python's various accessors, but I also think there's real value in simplifying these. We have some of that with property (and in one man's opinion, yay), and that allows us to avoid many methods (my general policy is that getting a property should never have side-effects, but otherwise zero-argument methods are fair game for propertyization). The attribute/dictionary distinction still exists, though.

I think my general rule will be: don't use __getitem__ unless you really want to create something dictionary-like. (Or maybe if you want to use attributes that aren't valid Python identifiers; then __getitem__ and __getattr__ maybe should be synonyms)