These are mine:
- Keep things simple.
- Layering/encapsulation and good API design are the keys to good programming.
- Too much abstraction is as bad as too little.
- Minimize code dependencies and specially temporal dependencies: I specially hate the case when you have an object that requires its methods to be called in a particular order and that is manipulated from different layers. Impossible to follow code!
- If you have to write some complicated piece of code, try to hide it behind and easy to use API.
- Code flow must be easy to follow.
- Perl is a powerful and expressive language, don't be afraid to use it to its maximum.
- Avoid code duplication. Don't copy&paste. Boilerplate is OK to a certain degree.
- Make your subs/methods meaningful.
- Try to avoid helper subs/methods with long lists of arguments.
- Don't use an object when a simple hash or array will do.
- Speed matters, scalability matters, memory usage matters, IO matters. Keep that in your mind while programming.
- When breaking some of the previous rules, document it.
- Check the validity of your input (specially when dealing with external input), refuse anything you don't know how to handle: Note that this does not go against the robutness principle, they are orthogonal concepts.
- Write regular expressions as strict as possible.
- Check for errors extensively. Don't ignore them.
- Include internal consistence checks.
- Add lots of debugging code so that you may be able to debug problems reported by others even when you are not able to reproduce them.
- Depending on an external module needs a good justification.
- use strict, use warnings, selectively disable them when required.
- No TDD, it gets on the way of my iterative design/programming thinking process (but if it works for you I am OK with it).
- Otherwise, testing is a very good thing.
- Be consistent in your coding style.
- And use a good editor that takes care of it for you: actually I don't care too much about cosmetics, as far as blocks are indented it is OK for me.
- Finally, paraphrasing the great Salvor Hardin, "Never let your sense of best practices prevent you from doing what is right!"