Stefan Behnel <stefan_ml <at> behnel.de> writes: > > From a Cython perspective, I find the lack of efficient subclassing after such > a change particularly striking. That seriously bit me in Py2 when I tried > making XML text content a bit more intelligent in lxml (i.e. make it remember > what XML element it originated from).
I've used a library which had adopted this kind of behaviour (I think it was BeautifulSoup). After using it several times in a row I noticed memory consumption of my program exploded. The problem was that the library was returning objects which looked innocently like strings, but internally kept a reference to a multi-megabyte HTML tree. The solution was to convert them explicitly to str before storing them for later use, which defeated the point of having an str-derived type. In these cases I think it's much friendlier to the user of the API to use composition rather than inheritance. Or, simply, just return a raw string and let the user keep the context separately if he wants to. PS: what do you call "efficient subclassing"? if you look at the current implementation of unicode_subtype_new() in unicodeobject.c, it isn't very efficient (everything including the raw data buffer is allocated twice). _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
