Replaceable

What’s the mark of successful code?

Many would assume it’s code that remains untouched for years. If the code hasn’t touched, it must mean that it works and works well, right?

Perhaps surprisingly, I consider code longevity to be a potential flag of systemic weakness rather than strength.

What’s a better measure in my mind?

How easy is it to remove or replace a given unit of code.

If code units are made “fragile” by making them easy to break and remove from the system, you end up with a system that’s easy to change. It can pivot quickly to changes in the market and business. The system as a whole becomes more resilient and adaptable.

By contrast, if a unit of code becomes “durable”, or nearly impossible to remove, now your entire system is at the mercy of that code.

Now, replace code with individuals, processes, or external dependencies in your organization.

How “fragile” are they? The more “fragile” they become, the more the system as a whole becomes resilient in the face of unexpected change.