Lately I have been using the DateTime module for handling dates. While it cuts down on some of the laborious aspects of dealing with time intervals and date formatting there are some methods that can be confusing.
1) delta always returns positive. I have been advised to use delta to get the differences between days, however it always returns a positive number. I imagine there is a good reason for this and it would be great if someone could tell me why it is useful when you have alternatives such as subtract().
2) now() always comes back in UTC Unless you read the docs it is easy to assume that you are going to get now() in your own time zone.
Given that daylight savings time observed in different ways in different countries, converting time-zones is confusing. The correct way to subtract dates with datetime according to the docs: Always do your date math in UTC. Then you can convert the dates to whatever timezone is appropriate when its time to display the results.
It looks to me like DateTime makes time manipulation simple enough without glossing over important details. Given it is tricky when the default is utc but one can easily come to an understanding of the module's behavior if they test appropriately.
For Docs Go to the CPAN