[Python-Dev] dateutil (original) (raw)

Greg Ewing greg at cosc.canterbury.ac.nz
Mon Mar 15 20:05:28 EST 2004

Aahz <aahz at pythoncraft.com>:

Part of the problem is that relativedelta does need to be a single complex object. Consider

today() + relativedelta(month=1, dayofweek=FRIDAY) contrasted with today() + relativedelta(weeks=4, dayofweek=FRIDAY)

I'm not sure what point you're trying to make here. Even if it's true that a single composite operation is required, I don't see any reason it has to be written using the '+' operator.

Moreover, your first example tends to suggest that a single composite operation is not always what is needed. Written that way, it's ambiguous whether it means to go to a Friday and then forward one month, or to go forward one month and then to a Friday, which could give a different result.

It seems to me there are really two consecutive operations there, and their order matters. Given that, it would seem more sensible to write it as something like

d2 = friday_of(next_month(d1))

or

d2 = next_month(friday_of(d1))

depending on which one you want.

Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | A citizen of NewZealandCorp, a | Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. | greg at cosc.canterbury.ac.nz +--------------------------------------+

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