I've been working on some slightly complicated code with a myriad of bad design decisions over the course of a decade, and a total absence of test suite. I knew I needed some code reusability in my tests but I had no idea of exactly how much without making a quick start. Meanwhile my brain was filled with ancient code from which I was expurgating zombies, and had issues understanding multi-vendor interactions, so I wanted some bare minimum reusability to make engineering failure conditions easier.

(Moved from reddit.com/r/perl now that blogs.perl.org seems to be behaving itself).

Over the past year or so I've had to deal with PPI for parsing and rewriting perl code a handful of times. Refactoring scripts are generally one-shot single purpose. Like any data mangling activity refactoring scripts can get messy because they're generally disposable, so architecture tends to be an afterthought at best. You can kind of tell this if you go and read Perl::Critic policies. They're plagued by boilerplate and repetitive code, and that's for code that is extensively reused. The problem multiplies in the case where you're writing throwaway code against PPI. In this post I'm going to show off PPIx::Refactor, which is a minimal interface to contain a small but annoying part of the mess.