Writing Debuggable Code

Writing Debuggable Code

• Every function that has a return value, should be inspected.
• Debug trace logs at entry and exit of function to dump input/outputs.
• Debug trace at system call, library calls to dump the return values.

• Logs at important stages to identify flow of code. It should be possible to get some sense of where the problem is just from the logs, without need for recompile.

• Protect code from invalid data at entry points like cmdline args, UI, system call, DB, network, file, etc.
• Catch exceptions, fail with big splash, highlight the error, print error condition as specifically as possible.
• Validate output of library calls, return values, and other artifcats.
• Have consistent method of handling, expected errors and exception errors.
• Protect code from other people’s mistakes, from your own mistakes. Use assertions in place.

• Instead of too many checks, use type safety, scope localization methods to avoid errors.

http://swreflections.blogspot.in/2012/03/defensive-programming-being-just-enough.html