For this week’s entry, I’m taking a look at a module I first learned about in December 2009 while reading RJBS‘s Advent Calendar for that year: Sub::Exporter. I highly recommend his yearly calendar, as it is a great way to learn about new and interesting modules and features. Of course, it helps to actually use the things you find interesting: while I learned about this module over a year and a half ago, I’d completely forgotten about it until someone mentioned it during one of the talks as OSCON last week. Then I came across it in my notes on modules to consider for this series, and decided I’d best write about it soon, lest I forget it again!
Rather than going into an exhaustive explanation of what this module is, I invite you to take a quick look at the original advent calendar posting. Go ahead, I’ll wait. Done? Great!
Now, if you didn’t just check that out, or if you thought it was too long and just skimmed over it, here’s the short version: Sub::Exporter is a super-version of the core Exporter module. It allows other modules and scripts to import the routines you’ve chosen to export. But unlike Exporter, it gives both you and the user of your module a great range of flexibility in options and configuration of the routines that are exported/imported.
So, it can do everything that Exporter does, but it can also do a whole lot more. To me, the most useful feature of Sub::Exporter is the ability to rename an imported function when you import it. I have, in the past, had to opt to not import a given subroutine in order to avoid name-clashes between different modules. I would have to choose which one “wins”, and then use the full package name to call the other package’s routine. With Sub::Exporter, this is not only a fixable problem, it’s also the simplest of the examples of Sub::Exporter use.
The module is well-documented, coming not only with a basic manual page but also a tutorial page and a cookbook page. If only more modules did this! (I say that, but none of my modules do that, so I have no room to cast aspersions.) It is also fairly lightweight in both its own code and its dependencies (unlike last week’s PMM, which I later learned requires that you have Moose installed, even though it doesn’t use Moose directly).
I won’t necessarily replace all my usage of Exporter with Sub::Exporter— I think that some names are sufficiently unique as to avoid potential clashes— but I will certainly be using it in the future.