Unfixable Code

Over the years I’ve come to believe something that I’m not sure others will agree with. I would like to hear your point of view on it.

I posit that some code can become literally unfixable. Programmers can paint themselves into a corner with the code and it becomes impossible to get out again.

humpty

The scenario arises when a specific set of conditions exists:

  • the code is difficult to work with for some reason — inherent complexity, badly written code, whatever
  • the code is not tested and is not written to be testable
  • bugs are high-stakes, so changes are extremely risky
  • the code needs to be changed for some reason (it’s buggy or doesn’t fulfill its requirements)

This situation is a deadlock. I can’t leave the code as it is, because it has bugs that are causing problems that need to be fixed. I can’t change the code, or I’ll cause bugs that may be truly serious in a variety of ways. I can’t test the code, because it’s untestable the way it’s written. I can’t refactor it to be testable for the same reasons I can’t just change it in the first place.

I have encountered such code many times in my career. I’ve also met people who say they can fix any code with enough work. I haven’t seen that happen. The only solution I’ve seen is a complete replacement, rewriting from scratch.

What do you think?

PS: I remember seeing claims that if more than a small amount (10% or so, as I recall?) of a program’s code needs to be modified, a rewrite from scratch will be a better outcome in less time. If you can find any sources for that claim, please leave them in the comments.


About The Author

Baron is the founder and CEO of VividCortex. He is the author of High Performance MySQL and many open-source tools for performance analysis, monitoring, and system administration. Baron contributes to various database communities such as Oracle, PostgreSQL, Redis and MongoDB.


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