[Python-Dev] Make _strptime only time.strptime implementation? (original) (raw)

Brett C. drifty@alum.berkeley.edu
Sat, 10 May 2003 11:29:21 -0700

Guido van Rossum wrote:

[Brett]

I got a single email from someone asking me to change the functionality so that it would raise an exception if part of the input string was not parsed. [Guido van Rossum] That sounds like a good idea on the face of it. Or will this break existing code? [Brett] Maybe. If they depend on some specific behavior on a platform that offers it, then yes, there could be issues. But since the docs are so vague if it does break code it will most likely be because someone didn't follow the warnings in the spec. If you add some flag to control this behavior, defaulting to strict, then at least people who rely on the old (non-strict) behavior can use the flag rather than redesign their application. But the problem is that I have no idea what the old behavior is. Since the spec is so vague and open I have no clue what all the various libc versions do. I have just been patching strptime the best I can to handle strange edge cases that pop up and work as people like Kevin need it to. OK. Maybe I misunderstood (I've now got to admit that I've never tried strptime myself). From your initial message (still quoted above) I thought that it was a simple case of strptime parsing as much as it could and then giving up (sort of like sscanf), and that the suggestion you received was to make it insist on parsing everything or fail. I still think that would be a clear improvement. But if the original situation wasn't as clear-cut, maybe I should have stayed out of this...

I wasn't clear enough. I already patched strptime to raise an error if there is anything left that was not parsed (my first CVS checkin actually); this functionality is already there. So I think we just talked ourselves in a circle. =)

Unless you are suggesting a flag that when set controls whether the Python version or a libc version if available is used, which I guess could work as a transition to get people to move over. Is this what you are getting at, Guido? And if it is, do you want it at the function or module level? I say function, but that is because it would be easier to code. =) No, that's not what I was going for at all -- I think that would be a mistake that woud just cause people to worry needlessly about which strptime version they should use.

Well, now that I think we have the whole strict parsing cleared up, I assume we don't need this anymore. Is there any other worries?

-Brett