NAME
Date::Calc::Endpoints - Generate start/end dates easily, based on type
(year, month,...), number of consecutive entities ("4 months"), number
of intervals from the current date, and direction (past/future).
VERSION
1.00
SYNOPSIS
use Date::Calc::Endpoints;
my $dr = Date::Calc::Endpoints->new(%params);
my ($start_date,$end_date,$last_date) = $dr->get_dates();
my ($start_date,$end_date,$last_date) = $dr->get_dates(%params);
$dr->set_type([ YEAR | QUARTER | MONTH | WEEK | DAY ]);
$dr->set_intervals(n);
$dr->set_span(n);
$dr->set_sliding_window([ 0 | 1 ]);
$dr->set_direction([ '+' | '-' ]);
$dr->set_start_day_of_week([ MONDAY | TUESDAY | ...]);
$dr->set_start_day_of_month([ 1, 2, 3, ... 28 ]);
$dr->set_start_month_of_year([ 1, 2, 3, ... 12 ]);
$dr->set_today_date('YYYY-MM-DD');
$dr->get_error();
DESCRIPTION
Date::Calc::Endpoints calculates a start/end date based on a interval
type, and a number of intervals from the current date. This is often
required in running scheduled and ad-hoc reports using the same script,
where the desired date range has the requirement of, "7 months ago", or,
"5 weeks ago, running Tuesday to Monday".
Three dates are returned for the given interval:
* First date of the interval
* First date of the next interval
* Last date of the interval
Two "end" dates are returned for convenience, as a report using a
date+time field may require a query from "2015-10-01 through
2015-11-01", but the title of the report may be, "Output for 2015-10-01
through 2015-10-31".
Date ranges are calculated based on the following parameters:
* type - the basic time interval for the report [ YEAR | QUARTER |
MONTH | WEEK | DAY ] - no default, must be specified
Note: QUARTER calculates the ranges for (Jan-Mar / Apr-Jun / Jul-Sep
/ Oct-Dec)
* intervals - how many "units in the past" (eq, "4 months ago") -
default = 1
* span - number of consecutive units (eq, "5 month window") - default
= 1
* sliding_window - Applicable if span > 1. If sliding_window is set,
each interval back will slide by one unit of type. If sliding window
is not set, each interval back will slide by (span) units of type. -
default = 0
* direction - If set to "-", each positive value for "intervals" goes
further into the past, and each negative value for "intervals" goes
further into the future. If set to "+", the opposite applies.
* start_day_of_week - For type = WEEK, the day which should be used as
the first day of the week (SUNDAY, MONDAY, ...) - default = MONDAY
* start_day_of_month - For type = MONTH, the day which should be used
as the start date of the month. Valid values are 1..28. Date::Calc
is used for these calculations. If adding/subtracting months, and
the day component of the start month is greater than the number of
days in the resulting month (ex, "Feb 30"), Date::Calc extends the
calculation into the following month ("Mar 2"). To prevent
confusion, Date::Calc::Endpoints only supports start_dom of 1 to 28.
* start_month_of_year - For type = YEAR, the month which should be
used as the first day of the year. Valid values are 1..12. This
would be applicable for fiscal years, which do not always start with
*January*.
* today_date - Overrides the current date, typically for
development/test purposes.
The current window (intervals = 0) contains the current date.
Illustrations
The following tables illustrate the effect of various values of
direction, sliding window, and interval, assuming span = 2. Notice in
each case, "interval=1" is one unit away from the one containing the
current date (C).
Direction = "-", sliding window = 0
-3| -2| -1| C | 1 | 2 | 3
---|---|---|---|---|---|---
-1) | | | | |xxx|xxx
0) | | |xxx|xxx| |
1) |xxx|xxx| | | |
Direction = "-", sliding window = 1
-3| -2| -1| C | 1 | 2 | 3
---|---|---|---|---|---|---
-1) | | |xxx|xxx| |
0) | |xxx|xxx| | |
1) |xxx|xxx| | | |
Direction = "+", sliding window = 0
-3| -2| -1| C | 1 | 2 | 3
---|---|---|---|---|---|---
-1) xxx|xxx| | | | |
0) | |xxx|xxx| | |
1) | | | |xxx|xxx|
Direction = "+", sliding window = 1
-3| -2| -1| C | 1 | 2 | 3
---|---|---|---|---|---|---
-1) | |xxx|xxx| | |
0) | | |xxx|xxx| |
1) | | | |xxx|xxx|
METHODS
new
Object constructor. Parameters can be set here, or in get_dates, or by
set_*param* methods.
Arguments: *\%parameters*
my ($start, $end, $last) = $dr->new(*\%parameters*);
type => [ *YEAR | QUARTER | MONTH | WEEK | DAY* ]
Interval type. No default value - must be specified.
intervals => *n*
Number of intervals to move back/forth from the current interval.
Default = 1.
span => *n*
Number of *type* to include in the range. Default = 1.
start_day_of_week => [ *MONDAY | TUESDAY | WEDNESDAY | ...* ]
For *type = WEEK*, the day to denote the first day of the week.
Default = MONDAY.
start_day_of_month => [ *1, 2, 3...28* ]
For *type = MONTH*, the day to denote the first day of the month.
Default = 1.
sliding_window => [ *O | 1* ]
Applicable when span > 1. If *sliding_window=1*, each successive
*intervals* results in a shift of *span* (years, months, etc). If
*sliding_window=0*, each successive *intervals* results in a shift
of one (year, month, etc). Default = 0.
direction => [ *"+" | "-"* ]
If *direction="-"*, *intervals* progresses further into the past. If
*direction="+"*, *intervals* progresses further into the future.
Default = "-".
get_dates
Main method. Returns *start_date*, *end_date*, and *last_date*.
Arguments: *\%Parameters*
my ($start, $end, $last) = $dr->get_dates(*\%parameters*);
Any of the parameters set in *new* may be set/overridden here.
Accessors
Each of the parameters may be set/restrieved using set_*param* /
get_*param* methods.
set_intervals / get_intervals
Interval type: [ *YEAR | QUARTER | MONTH | WEEK | DAY* ]. No default -
must be specified.
set_span / get_span
Overrides the ranges running only one year/quarter/month/week/day at a
time. Default = 1.
set_start_day_of_week / get_start_day_of_week
For weekly ranges, defines the starting day to be used for the week, [
*MONDAY | TUESDAY | WEDNESDAY | ...* ]. Default = Monday.
set_start_day_of_month / get_start_day_of_month
For monthly ranges, defines the starting day to be used for the month.
Only supported values are 1-28, as months with less than 31 days may
yield results unexpected by the end user. Default = 1.
set_start_month_of_year / get_start_month_of_year
For yearly ranges, defiens the starting month to be used. The starting
day is fixed at 1. Default = 1 (January)..
set_today_date / get_today_date
By default, the current date is used. This can be overridden, for
development/test purposes. Format must be YYYY-MM-DD.
set_sliding_window / get_sliding_window
Applicable if span > 1. Determines whether successive intervals move an
entire span, or just a single amount of type. For instance, if type =
MONTH and span = 5, should each successive value of *intervals* advance
one month at a time, or five months at a time. Default = 0 ("five months
at a time").
set_direction / get_direction
The direction which successive intervals progresses. This allows for
positive values of *interval*, whether looking into the past, or into
the future. To get date ranges which are further into the past,
recommend setting direction to "-". If date ranges in the future are
required, recommend setting direction to "+". Default = "-". Refer to
the Illustrations section for examples.
get_error
Retrieve any errors detected by the object.
clear_error
Reset the error stack
EXAMPLES
Date is 2015-10-10, type = 'MONTH', direction = '-', span = 1. Such a
setup would be used for running monthly reports.
Intervals = 0 would be the current month:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH');
my ($start, $end, $last) = $dr->get_dates(intervals => 0);
(2015-10-01, 2015-11-01, 2015-10-31)
Intervals = 4 would be four months prior to this:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH');
my ($start, $end, $last) = $dr->get_dates(intervals => 4);
(2015-06-01, 2015-07-01, 2015-06-30)
If "intervals" is a negative number, ranges would be in the future
(improbable, but supported):
my $dr = Date::Calc::Endpoints->new(type => 'MONTH');
my ($start, $end, $last) = $dr->get_dates(intervals => -1);
(2015-11-01, 2015-12-01, 2015-11-30)
Date is 2015-10-10, type = 'MONTH', direction = '-', span = 5. Sliding
window now becomes relevant.
Intervals = 1 should still be the most recent, completed period. If
sliding_window = 0:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH', span => 5);
my ($start, $end, $last) = $dr->get_dates(intervals => 1);
(2015-05-01, 2015-10-01, 2015-09-30)
Intervals = 0 will be the next period, starting with the current month:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH', span => 5);
my ($start, $end, $last) = $dr->get_dates(intervals => 0);
(2015-10-01, 2016-03-01, 2016-02-29)
Now, if sliding window is enabled, intervals = 1 should still be the
most recent, completed period:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH', span => 5, sliding_window => 1);
my ($start, $end, $last) = $dr->get_dates(intervals => 1);
(2015-05-01, 2015-10-01, 2015-09-30)
This time, intervals = 0 will end with the current month:
my $dr = Date::Calc::Endpoints->new(type => 'MONTH', span => 5, sliding_window => 1);
my ($start, $end, $last) = $dr->get_dates(intervals => 0);
(2015-06-01, 2015-11-01, 2015-10-31)
All parameters can be set at instantiation, set distinctly, or passed in
with get_dates.
my $dr = Date::Calc::Endpoints->new(type => 'MONTH', intervals => 1);
my ($start, $end, $last) = $dr->get_dates();
(2015-09-01, 2015-10-01, 2015-09-30)
$dr->set_intervals(2);
my ($start, $end, $last) = $dr->get_dates();
(2015-08-01, 2015-09-01, 2015-08-31)
my ($start, $end, $last) = $dr->get_dates(intervals => 3);
(2015-07-01, 2015-08-01, 2015-07-31)
DIAGNOSTICS
Any errors detected may be retrieved via *$dr->get_errors*. Errors are
accumulated as they are encountered. They are cleared only when
*$dr-*clear_errors> is invoked.
DEPENDENCIES
Class::Accessor
Date::Calc
AUTHOR
T. Olenchuk
LICENSE / COPYRIGHT / DISCLAIMER
This is free software, you may use it and distribute it under the same
terms as Perl itself. There is no warranty of any kind, either expressed
or implied.
LIMITATIONS
* The only allowed format for returned dates is 'YYYY-MM-DD'.
* "Start day-of-month" is only valid only for values 1-28. This was to
avoid trying to use last-day-of-month, which becomes problematic for
days with less than 31 days. Arguments could be made that, "one
month after the last day of January" is Feb 28, or March 3, or even
March 4 on a leap year.
* Any date calculations not supported by Date::Calc are not supported
here, such as "3000 years ago".