[Python-Dev] Interop between datetime and mxDateTime (original) (raw)

Guido van Rossum guido@python.org
Mon, 13 Jan 2003 21:09:00 -0500

[Guido] > The proposal also recomments an abstract base type, "basetime", for > all time types. Without this, cmp() is hard to do (see Tim's post for > explanation; we don't want datetime objects to be comparable to > objects with arbitrary other types, because the default comparison iss > meaningless). > > This could be a pure "marker" type, like "basestring". Marc-Andre, > if we export basetime from the core, can mxDateTime subclass from > that?

[Tim]

Let me ask a question: when I tried to make datatime.tzinfo a pure "marker" type, I eventually had to give up, because I absolutely could not make it work with pickling (and recalling that pickles produced by datetime.py had to be readable by datetimemodule.c, and vice versa). Instead I had to make it instantiable (give it an init method that didn't complain), and require that tzinfo subclasses _also have an init_method callable with no arguments. Are we able to get away with basestring because pickle already has deep knowledge about Python's string types?

Detail to be worked out. If the only way to make pickling work is to make basestring instantiable, so be it.

--Guido van Rossum (home page: http://www.python.org/~guido/)