Comment by MaxBarraclough

Carmack's writing on the proper length of functions (although he expresses it in terms of when to inline a function): https://news.ycombinator.com/item?id=8374345

A choice quote from Carmack:

> The function that is least likely to cause a problem is one that doesn't exist, which is the benefit of inlining it. If a function is only called in a single place, the decision is fairly simple.

> In almost all cases, code duplication is a greater evil than whatever second order problems arise from functions being called in different circumstances, so I would rarely advocate duplicating code to avoid a function, but in a lot of cases you can still avoid the function by flagging an operation to be performed at the properly controlled time. For instance, having one check in the player think code for health <= 0 && !killed is almost certain to spawn less bugs than having KillPlayer() called in 20 different places.