Proposed API change: netcdftime.datetime should be immutable

[shoyer]

If we make netcdftime.datetime immutable, we can define a __hash__ method and thus use these objects as a dictionary keys. Note that python's standard library datetime.datetime object is immutable for precisely this reason.

Why is this useful? In xray, we use netCDF4 to decode dates with non-standard calendars, and (currently) store the results as an array of netcdftime.datetime objects. If these objects were hashable, it would be possible to use datetime objects to perform fast location based lookups (using a hash table) along a time dimension labeled by these phony datetime objects.

I doubt that this will break anyone's code, since it would be weird to mutate a datetime object in-place, but since this would change the existing API I thought it would be worth discussing before filing a pull request. At the very least, I think mutating a datetime object should be deprecated, so that it is possible change this behavior in a future release.

[jswhit]

Sounds reasonable to me.

[jswhit]

Is a pull request coming?

[shoyer]

Yes, when I have the time to get it together :).

On Wed, May 14, 2014 at 12:48 PM, Jeff Whitaker [email protected]
wrote:

Is a pull request coming?

Reply to this email directly or view it on GitHub:
#255 (comment)

[jswhit]

No problem, just checking..