Discussion

Every function should be a coherent unit of work bearing a suggestive name (see Item 5 and the Discussion in Item 70). When a function instead tries to merge such small conceptual elements inside a long function body, it ends up doing too much.

Excessive straight-line function length and excessive block nesting depth (e.g., if, for, while, and try blocks) are twin culprits that make functions more difficult to understand and maintain, and often needlessly so.

Each level of nesting adds intellectual overhead when reading code because you need to maintain a mental stack (e.g., enter conditional, enter loop, enter TRy, enter conditional, …). Have you ever found a closing brace in someone's code and wondered which of the many fors, whiles, or ifs it matched? Prefer better functional decomposition to help avoid forcing readers to keep as much context in mind at a time.

Exercise common sense and reasonableness: Limit the length and depth of your functions. All of the following good advice also helps reduce length and nesting:

• Prefer cohesion: Give one function one responsibility (see Item 5).

• Don't repeat yourself: Prefer a named function over repeated similar code snippets.

• Prefer &&: Avoid nested consecutive ifs where an && condition will do.

• Don't try too hard: Prefer automatic cleanup via destructors over TRy blocks (see Item 13).

• Prefer algorithms: They're flatter than loops, and often better (see Item 84).

• Don't switch on type tags. Prefer polymorphic functions (see Item 90).