Jonas B.Nielsen wrote:
>
> Well I really the general idea of a
DateTime::Calc::Namespace, but I
> think the case of DateTime::Pregnancy
(Date::Pregnancy now) really
> shows the difficulty of generalizing such a thing.
>
> In calculating a date a of birth I currently have
knowledge of 3
> different methods. They all differ at bit but all
calculate from the
> first day of the last period and from the you can
somewhat deduct the
> conception date.
>
> So the conception date indicating the start of the
pregnancy is
> something, which is not known when initializing the
DateTime object
> calling the constructor. This could of just be
documented, but I think
> it conflicts a bit with the idea of a start and an
end, also since the
> main functionality in Date::Pregnancy is
calculating the end date.
>
> So a DateTime::Calculate::Pregnancy could be used
to measure the length
> of a pregnancy for comparison etc. I am not saying
that it would be
> impossible to implement DateTime::Calc::Pregnancy
based in
> Date::Pregnancy, but the world of pregnancy
calculation is a bit
> upside-down compared to normal calendar usage if
you get my point.
>
This could be implemented as a
DateTime::Event::Spreadsheet "bidirectional
calculator" - from the docs:
# - given a birthday, calculate the age;
# - given an age, calculate the birthday.
use DateTime::Event::Spreadsheet;
# setup the Spreadsheet
[ ... some initialization hidden ... ]
# test the Spreadsheet
$dtes->set(
birthday => DateTime->new( year=>1964,
month=>12, day=>14 )
);
my @age = $dtes->get( 'age' )->deltas;
print "Age is @age\n";
$dtes->set(
age => DateTime::Duration->new( years => 20 )
);
my $birthday = $dtes->get( 'birthday' )->datetime;
print "Birthday was $birthday\n";
For example, you could add 'conception' and 'last
period' cells to this spreadsheet.
(DateTime::Event::Spreadsheet is in DateTime CVS)
- Flavio S. Glock
