cloc (Count Lines Of Code) counts, and computes differences of, comment lines, blank lines, and physical lines of source code in many programming languages.
cloc is now being developed at https://github.com/AlDanial/cloc
A Ruby file parser/interpreter/preprocessor that comments lines of code based on conditions at the time the file is required. Very handy to implement debugging logs and code that has to be commented (not just dynamically switched off).