[Zope3-dev] Can we remove ZopeLegacy for now?

[Phillip J. Eby]

At 06:00 PM 3/16/02 -0500, Tim Peters wrote:

>OK, what's the intent?  The page says
>
>     tz.tzoffset(dt) - given a datetime object, returns the timezone
>     offset in seconds east of UTC (negative west of UTC) corresponding
>     to that date and time
>
>I expect the docs don't mean what they appear to say, or are leaving too
>much unsaid.  "That date and time" doesn't *mean* anything concrete unless
>you tell me the time system it's measured in.

IIUC, 'dt' is to be interpreted as being in tz's time system if it is a 
plain 'datetime' as opposed to a 'datetimetz'.  If it is a 'datetimetz' 
with a different tzinfo than 'tz', then presumably  tz must convert 'dt' to 
UTC or its own time system first.  Since it can ask the other tzinfo object 
for a UTC offset for 'dt', it provably can perform this conversion.

Of course, if 'tz' is a constant offset, then there's no need to look at 
the value of 'dt' at all.  :)

IMHO, for ease of conversion, it would be better if tzinfo objects 
supported methods to return a datetime (or at least the datetime field 
values) from a linear time value (such as Unix clock ticks), and vice versa.