NAME DateTimeX::Immutable - An immutable subclass of DateTime VERSION version 0.34 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. TODO: Talk about why this is a good idea, how it is implemented, and how this differs from alternate approaches. See DateTime for the rest of the documentation. SEE ALSO DateTime, DateTime::Moonpig, Time::Moment AUTHOR Mark Grimes, COPYRIGHT AND LICENSE This software is copyright (c) 2014 by Mark Grimes, . This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.