[Python-Dev] Broken strptime in Python 2.3a1 & CVS (original) (raw)

Guido van Rossum guido@python.org
Tue, 14 Jan 2003 16:46:17 -0500

[Guido van Rossum]

> > > The C wrapper around strptime.strptime() stays, of course. It > > > currently has a bit of an inefficiency (what happens when it tries to > > > import strptime is a lot more than I'd like to see happen for each > > > call) but that's a somewhat tricky issue that I'd like to put off for > > > a little while; I've added a SF bug report as a reminder. (667770) > > > > > > > Anything I can do to help with that? If it is just a matter of re-coding > > it in a certain way just point me in the direction of docs and an example > > and I will take care of it. > > The issues are really subtle. E.g. you can't just store the python > strptime function in a global, because of multiple independent > interpreters and reload(). You can't peek in sys.modules because of > rexec.py. > Now I really wish we were ripping rexec out instead of crippling it. =)

Um, the issues aren't really rexec.py itself, but the general security framework; I think there's still something to say for that in the long run (even though right now it's not secure).

> If you still want to look into this, be my guest.

I will see what I can do, but it sounds like this is beyond my experience. > > And to comment on the speed drawback: there is already a partial solution > > to this. strptime has the ability to return the regex it creates to > > parse the data string and then subsequently have the user pass that in > > instead of a format string:: > > > > strptimeregex = strptime.strptime('%c', False) #False triggers it > > Why False and not None? Just playing with booleans at the time. =) I also thought that it made sense: False as in it is false that you are going to get any info out of this. Although, None also makes sense. I can change it easily enough.

Please fix.

> > for line in logfile: > > timetuple = strptime.strptime(strptimeregex, line) > > > > That at least eliminates the overhead of having to rediscover the locale > > information everytime. I will add a doc patch with the patch that I am > > going to do that adds the default values explaining this feature if no one > > has objections (can only think this is an issue if it is decided it would > > be better to write the whole thing in C and implementing this feature > > would become useless or too much of a pain). > > Yeah, but this means people have to change their code. OK, I think > for speed hacks that's acceptable.

So then I can document it, right? Or should we just leave this as a surprise for the more adventurous who read the source?

No, it would be better if you ripped out any other undocumented "surprises" that might still be lurkig in _strptime.py. Or at least owe up to them now so we can decide what to do with them.

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