RFC2: Date/Time proposal

[Nathan Buchanan]

On 7/19/08, Charles Day <cedayiv at gmail.com> wrote:
>
> I'm going to go ahead and throw out another proposal for comments. I'm
> calling this RFC2. Unless specifically stated, all that follows refers to
> transaction posting dates and times only.
>
> Since to my knowledge the feature of having a "time zone per account" has
> not actually been requested by any user, I'm going to leave that completely
> out of this proposal. However, if there ever was a need for that feature in
> the future, this proposal is readily extensible to support that.



First off, I agree that for most (maybe all?) cases the timezone per account
is not needed. That being said, I was a bit nervous removing the option of
adding timezones in the future, so I think this proposal better addresses
the needs without restricting things in the future.

Here's what I was thinking. The general idea is to allow "date only"
> functionality, but also allow optional entry of a time of day:
> 1. Let there be a checkbox preference named "Show transaction posting
> times". Off by default.
> 2. When this preference is off, registers look the same as today; a time of
> day is not seen and cannot be entered.
> 3. When this preference is on, users can enter a posting time of day on any
> transaction, but do not have to.
> 4. For each transaction, if a time of day has not been entered then the
> GnuCash data file will only save the date. Otherwise, both date and the
> time
> of day will be saved.


This is likely to become messy in the datafile: some dates without times and
some with times. When we read this data in, we would have to keep track of
which dates have times and which do not. I'd think it would be much simpler
to create a default time and always write out the time (assuming, of course,
that the user had not specified a time). And since the timezone is always
known, there will never be any ambiguity or shifting dates.

5. The user does not specify any time zone, and none is saved.


ok, though I'd advocate that the timezone be specified (and possibly saved)
as UTC. If we do not do this, the user may decide to change the timezone on
their machine while gnucash is open and possibly save different data than
was read in.

6. In case the user has some transactions with times and some without, and
> needs to sort transactions by posting time, let there be a preference
> exists
> to determine how to treat the transactions that do not have posting times.
> (Possible options might include treating them as if they had been entered
> at
> the beginning of the day, or at the end of the day, or at any specific time
> in between.)


I'd allow a default transaction time instead, as above.

Sound good? Well, here's the part you may not like. All of the above can be
> implemented by GnuCash internally by use of a timestamp and a flag
> indicating whether the time of day was entered by the user. Let me explain:
> A. All timestamps would use the same time zone, which never varies. Users
> do
> not pick the time zone. It is hard coded and is never seen in the GUI and
> never saved to the data file.


Unless the user changes timezones with the file open...

Nathan

B. If a transaction is read from a data file and it contains both a date and
> a time, these are combined with the time zone from (A) to compute a
> timestamp. The flag is raised to indicate that the time of day was entered
> by the user.
> C. If a transaction is read from a data file and it contains only a date, a
> time of day is added on according to the preference indicated in (6) above,
> and these are combined with the time zone from (A) to compute a timestamp.
> The flag is lowered to indicate that the time of day was NOT entered by the
> user.
> D. To display the date in the GUI, GnuCash takes the time zone from (A) and
> the timestamp, and uses them to compute the date.

E. To (optionally) display the time in the GUI, GnuCash takes the time zone
> from (A) and the timestamp, and uses them to compute the time of day.
> F. When saving a transaction to the data file, if the flag is raised to
> indicate that the time of day was entered by the user, then GnuCash writes
> the date and time of day to the data file.
> G. When saving a transaction to the data file, if the flag is lowered to
> indicate that the time of day was NOT entered by the user, then GnuCash
> writes only the date to the data file.
>
> My reasons for suggesting the continued use of timestamps internally are
> that it makes it very easy to sort transactions by posting time, and that
> the necessary code changes to get this done is still fairly small. So there
> is probably some reasonable chance of it actually getting done, which is an
> important factor to consider. Several of you who want to use "date only"
> internally have made fair points about simplicity, but I have made the
> point
> that the effort of getting from here to there would be much larger. So you
> would have to ponder the question of who would devote the necessary time
> for
> that larger effort.
>
> OK, now praise this, ask questions, or rip it apart (more likely) as you
> see
> fit. Thanks to everyone so far for remaining fairly civil while discussing
> this potentially incendiary topic.
>
> Cheers,
> Charles
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>



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