Class-override of a sort-key method?

2010-12-20 Thread pythonlist . calin79
Hi all - it would seem that these days, all the cool kids use the sort
function's 'key' kwarg in order to sort a list of custom objects quickly.

Unfortunately, as opposed to using 'cmp', where you can implent __cmp__ to
get 'automatic sorting' in a similar fashion, there doesn't seem to be a
direct analogue for a class-overridable method for providing a sort key.
 (ie, something like '__sortkey__' or '__key__').

Is there one, and I'm just missing it? If not, are there any plans to add
one? (I did a quick search of the PEP list, and the only hits for 'sort' I
saw had to do with sorting dictionaries by value).

- Paul
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A 'foolproof' way to query inheritance tree? numbers.Real in 2.6)

2010-04-11 Thread pythonlist . calin79
Generally, if I want to know the inheritance tree of a class, I either
use inspect.getmro or __bases__

However, after reading about the new numbers module / class tower in
Python 2.6/3.0, I realized that both of these will fail to show that
the 'float' type actually inherits from numbers.Real:

>>> import inspect, numbers
>>> issubclass(float, numbers.Real)
True
>>> inspect.getmro(float)
(, )
>>> float.__bases__
(,)

Is there a more foolproof way to query this information? Or is this
simply some sort of bug with the new implementation of numbers in
python 2.6?

- Paul

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