Item 2. Enable new Perl features when you need them

Starting with Perl 5.10, you must explicitly enable new features. This ensures that the latest release of Perl can be backward compatible while at the same time letting people start new work using all of the latest nifty features.

For instance, Perl 5.10 adds a say built-in that is just like print except that it adds the trailing newline for you. Not only is your string a couple of characters shorter, but you don’t have to double-quote the string just for the newline: