Python - Dictionary - Modify __getitem__?

Question

Ok so i\'ve build my own variable handler which has a __getitem__ function for use when accessing data via data[key], it works great except for when trying to a

Answer 1

Remember: tmp = foo['bar']['baz'] is the same as tmp = foo['bar']; tmp = tmp['baz']

So to allow arbitrary depths your __getitem__ method must return a new object that also contains such a __getitem__ method.

Answer 2

The fact is that when Python encounters an expression such as data["key"]["subkey"], what is done internally is (data["key"])["subkey"]. That is, the first part of the expression is resolved: the retrievalof the item "key" from the object "data". Then, Python tries do call __getitem__ on the resulting object of that expression. If such resulting object does not have a __getitem__method itself, there is your error.

There are two possible workarounds there: you should either work with "tuple indexes" - like data["key", "subkey"](and then test on your __getitem__ method wether you got a tuple instance as the key) - or make __getitem__ return an specialized object that also features a __getitem__ method - even if all it does is to log the requested keys.