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

Greg Ewing greg at cosc.canterbury.ac.nz
Mon Mar 15 17:59:09 EST 2004

In dateutil, I think it's d + relativedelta(months=+1, day=1, days=-1). Arguably, this is fairly trivial (highly non-obvious, but trivial...)

Another thing that occurs to me. Presumably

d + relativedelta(months=+1) + relativedelta(days=-1)

is not necessarily the same as

d + relativedelta(days=-1) + relativedelta(months=+1)

so when you add two relativedeltas together, do you get a relativedelta that does things in the right order? In other words, can you do

rd = relativedelta(days=-1) + relativedelta(months=+1) d += rd

and get the same result as

d += relativedelta(days=-1) d += relativedelta(months=+1)

Also, there is presumably some order of precedence defined when you specify multiple adjustments in one constructor.

From your examples I'm guessing

relativedelta(months=+1, days=-1) ==
relativedelta(months=+1) + relativedelta(days=-1)

There could be a trap lurking here for the unwary, since obviously then

relativedelta(days=-1, months=+1) !=
relativedelta(days=-1), relativedelta(months=+1)

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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