On Fri, Nov 18, 2011 at 7:51 AM, GZ <zyzhu2...@gmail.com> wrote: > Hi, > > I have a class Record and a list key_attrs that specifies the names of > all attributes that correspond to a primary key. > > I can write a function like this to get the primary key: > > def get_key(instance_of_record): > return tuple(instance_of_record.__dict__[k] for k in key_attrs) > > However, since key_attrs are determined at the beginning of the > program while get_key() will be called over and over again, I am > wondering if there is a way to dynamically generate a get_ley method > with the key attributes expanded to avoid the list comprehension/ > generator.
(Accidentally sent this to the OP only) This is exactly what the attrgetter factory function produces. from operator import attrgetter get_key = attrgetter(*key_attrs) But if your attribute names are variable and arbitrary, I strongly recommend you store them in a dict instead. Setting them as instance attributes risks that they might conflict with the regular attributes and methods on your objects. Cheers, Ian -- http://mail.python.org/mailman/listinfo/python-list
