[Python-Dev] dateutil

[Kevin Jacobs]

Gustavo Niemeyer wrote:

>>>>> d.forward_months(3).end_of_month()
>>>>>          
>>>>>
>>>>In dateutil, I think it's d + relativedelta(months=+1, day=1, days=-1).
>>>>Arguably, this is fairly trivial (highly non-obvious, but trivial...)
>>>>        
>>>>
>>>Yes, it'd work, but "d + relativedelta(day=31)" would be enough.
>>>      
>>>
>>Hmm, I feel vaguely uncomfortable actually relying on the "round down out
>>of range values" behaviour. Presumably day=1000 would also work, and would
>>look even stranger to me :-)
>>    
>>
>
>This was a design decision, and I confess I'm pretty satisfied
>by the results of this decision. This simple decision created
>consistent and expectable results for operations which are not
>obvious. Also, without this feature, I see almost no reason for
>using this class instead of timedelta.
>  
>

The alternative way to getting the end of the month (which I used in my 
datetime class)
was to perform two adjustments:

 >> end_of_month = 
date.adjust_absolute(day=1).adjust_relative(month=+1,day=-1)

This requires that the relative adjustments are applied in order from 
most significant
adjustment to least.  Now that I've seen the Gustavo's semantics, I 
think his may be
more sensible (even though the particular gymnastics where hidden behind 
a helper-
method, so that most developers never had to know these subtleties).

-Kevin