I've been using it for years. This posting is not meant to be a comprehensive list of all the basic necessities. It is merely the most important things I learned since joining PM.

Every time I see production code without those two words up the top, I die a little inside. We've been transitioning servers at work this week and today when writing a new script I found a mailer module that wasn't working as expected. The reason:

my $Package = caller();
my $MailServer = eval "\$".$Package."::Settings{'MailServer'}";
[download]

All the existing modules had %Settings declared as a global so it worked. Eurgh.