I personally like to measure everything. I find that when I measure something it tends to improve.

Programming, however, is not an easily measurable activity.

A sales person can easily be measured by the amount of merchandise they sold. Similarly, a potter can be measured by the amount of pots they produced etc.

But in programming, often less is more. Writing a function using 25 lines of code is typically better than a function that does the equivalent using 250 LOC. Reusing an existing functionality to fulfill a new feature is far better than writing it from scratch. Etc.

So my question is, did anyone figure out a good way to measure a developer's productivity?