Decide whether Duration.OneMinute (etc) should exist

[GoogleCodeExporter]

Currently, Duration exposes a bunch of canned fields like Zero, OneMinute, 
NegativeOneTick, and so on.  It also exposes sensible operator overloads and 
factory methods, meaning that it's unclear as to whether 'a duration of three 
days' should be best constructed via:

Duration.FromStandardDays(3)
or
Duration.OneStandardDay * 3

I suggest that we pick one, and I'd tend toward the factory methods, rather 
than trying to provide a bunch of fields for 'common but not really' durations.

Alternatively, we should remove the factory methods (apart from FromTimeSpan()) 
and rationalise the common durations (removing NegativeOneTick in favour of 
-OneTick and adding OneStandardWeek).  But I'd prefer the former, I think.

Original issue reported on code.google.com by malcolm.rowe on 20 Apr 2012 at 1:47

[GoogleCodeExporter]

Oh, forgot to mention: Duration.Zero (and probably MinValue and MaxValue) do 
make sense, regardless of what we decide above.

Original comment by malcolm.rowe on 20 Apr 2012 at 1:48

[GoogleCodeExporter]

Agreed, let's get rid of at least most of the constants. Zero makes sense, and 
*potentially* OneTick as an equivalent of Epsilon to some extent. Maybe 
MinValue and MaxValue? OneWeek etc should go.

Original comment by jonsk...@google.com on 23 Apr 2012 at 8:31

[GoogleCodeExporter]

Fixed in revision 0cf928ea05d7.

We could also now decide to make e.g. FromStandardWeeks(1) return the 
OneStandardWeek constant (etc), but that's an optimisation we can do later if 
at all.

Original comment by malcolm.rowe on 23 Apr 2012 at 11:00

• Changed state: Fixed