Exceptions
Exceptions are meant to be… ehm… exceptional. Exceptions are thrown when the code could not be executed further. They are meant to be thrown right at the point where something went wrong and passed up the stack till the program termination. Programmer should only provide “ensure” (in Ruby; or “finally” in Java) block to clean up. Programmer should never use “catch”/“rescue” block. Never.
There’s one little thing, however.
Sometimes you run your program and get silly exceptions like “connection lost” or “division by zero”. You become unhappy about it and you decide to implement an interface to deal with such errors. For example, when connection is lost you could show a message or do something smart (depends on the purpose of your program, of course).
But please remember: never ever catch exceptions you don’t know about (no “rescue nil” or “rescue => e”!). You should be very picky at what you are catching. Uncaught exception simply pops up in a system message or a log entry, so you can learn it. But silently caught exception might hide some nasty error from your eyes. And you wouldn’t be able to see in a stack trace what had happened few milliseconds before.