Re: [boost] [date_time] Time zone improvements

Subject: Re: [boost] [date_time] Time zone improvements
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-25 07:15:05

grubino wrote:
>
> WRT the historical time zone change support, that's actually
> huge for me because without it I cannot use boost::date_time
> without it.

We found it necessary to create a mechanism for managing a reverse chronologically ordered set of time zone rules to account for historical changes.  We modified the zone names to include an optional delimiter and effective year which we split to regain the normal zone name and the year which is used as a key to finding the corresponding rule.  Thus, we determine the time zone data to apply to a given local_time by determining its year and then looking for the rule that was in effect as of that year.

Even with that logic, we still don't have support for zones with multiple transitions in a given year, such as occur when a state decides to ignore or recognize DST midway through a year or to switch from one time zone to another.

Perhaps we missed something in the provided time zone support that would have obviated our work.

_____
Rob Stewart                           robert.stewart_at_[hidden]
Software Engineer                     using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP  http://www.sig.com

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