Working With Legacy Code

Working with legacy code can pose many challenges but also many interesting opportunities to learn. In this post I’d like to go over a few key points to help navigate a legacy codebase.

Dividing Your Time

If you are actively adding new features to the codebase then it is essential that you carve out time to perform tasks to maintain the code. Everyone wants new things but if you’re just adding code on top without doing your due diligence, this can cause larger problems in the future when you finally address long standing issues. If you have the bandwidth, putting in the time now to get your codebase where it needs to be can help to reduce the complexity and effort needed to inevitably do it later. Breaking the code into sections and setting goals as you go can make the process much smoother.

Testing

When making changes to a legacy codebase, testing is essential. In many cases tests can be broken or just completely non-existent. To ensure that the refactoring or additions you are making to the code are safe you need to have tests in place. Without tests you’re going in somewhat blindly and just hoping things work out. It’s much better to save yourself the time by creating test coverage as you work through the codebase so that you can avoid a lot of troubleshooting later when making changes.

Dead Code

Removal of large areas of dead code can be very helpful for when you’re ready to do a significant upgrade of the code/environment. If you can spend some time analyzing and identifying unnecessary pieces of code you can assist in reducing confusion later on when trying to make changes. This is also helpful to possible future devs that will be attempting to understand the working code and reduce the amount of time wasted on dead code. There can also be cases where you may think you need to upgrade or replace a dependency only to find out that the only code that references it is dead.

Documentation

The importance of documentation is already widely recognized as an essential practice in programming. Though not only is documenting your own code helpful but also those that came before you. Old code can sometimes make adding features and fixing bugs much more complicated than they otherwise would be. In many cases those original developers are no longer actively working in the codebase and notes/comments might be sparse. Many devs know the feeling of banging your head against the wall on an issue so it would be great if we’re able to prevent that headache for the next person in our position. This can also be very beneficial in a not so altruistic situation where we just want to help ourselves avoid diving into some obscure issues for a few hours that we already solved in the past. Comments can be great but adding knowledge to some sort of central repository could be even better and get you to a solution much faster.

Conclusion

Working with a large legacy codebase can be very daunting, but if we take the time to do some things other than just writing code we can create an easier environment to work in. The key takeaway for me is to do what you can now to save yourself time and confusion later. Trying to navigate a complex issue on top of a very messy codebase can be pretty frustrating. The more we can ensure we have a nice environment to develop in, the easier we’ll be able to iterate on it and make much more rapid progress in the future.