/ 
Date-Calc-Endpoints-1.03
River stage zero No dependents
/ Date::Calc::Endpoints

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

1.03

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".