NAME

DateTimeX::Immutable - An immutable subclass of DateTime

VERSION

version 0.36

SYNOPSIS

    use DateTimeX::Immutable;
    my $now = DateTimeX::Immutable->now;  # 2012-12-12T11:15:10
    my $day = $now->with_hour( 0 )->with_minute( 0 )->with_second( 0 );
    say $now;           # 2012-12-12T11:15:10
    say $day;           # 2012-12-12T00:00:00
    $now->set_day( 1 ); # throws an exception

or with aliased:

    use aliased 'DateTimeX::Immutable' => 'DateTime';
    my $now = DateTime->now;  # 2012-12-12T11:15:10
    my $day = $now->with_hour( 0 )->with_minute( 0 )->with_second( 0 );
    say $now;           # 2012-12-12T11:15:10
    say $day;           # 2012-12-12T00:00:00
    $now->set_day( 1 ); # throws an exception

DESCRIPTION

This is subclass of DateTime which throws an exception when methods that modify the object are called. Those methods are replaced with new methods that leave the original object untouched, and return a new DateTimeX::Immutable object with the expected changes.

The following methods now thrown an exception:

    $dt->add_duration()
    $dt->subtract_duration()
    $dt->add()
    $dt->subtract()
    $dt->set()
    $dt->set_year()
    $dt->set_month()
    $dt->set_day()
    $dt->set_hour()
    $dt->set_minute()
    $dt->set_second()
    $dt->set_nanosecond()
    $dt->truncate()

and are replaced by these methods which return the changed value:

    $dt->plus_duration()
    $dt->minus_duration()
    $dt->plus()
    $dt->minus()
    $dt->with_component()
    $dt->with_year()
    $dt->with_month()
    $dt->with_day()
    $dt->with_hour()
    $dt->with_minute()
    $dt->with_second()
    $dt->with_nanosecond()
    $dt->trunc()

At the moment, set_time_zone, set_locale, and set_formatter continue to act as mutators. DateTime uses these internally and changing them creates unexpected behavior. These methods also do not really change the time value.

See DateTime for the rest of the documentation.

WHY

Reasons why this module eixsts:

Mutability is bad!

DateTime::Moonpig: Great idea but changes too much. We still want to be to truncate, set_*, etc, we just want the result returned. Changing the math goes beyond the scope of our needs. No integration with DBIC.

Time::Moment: Excellent, but for code that already uses DateTime we want to continue. Also, Time::Moment's plugin for DBIC doesn't support native db date formats.

(TODO: Expand on explanation for this module's existence.)

SEE ALSO

DateTime, DateTime::Moonpig, Time::Moment

AUTHOR

Mark Grimes, <mgrimes@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2015 by Mark Grimes, <mgrimes@cpan.org>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.