Is it acceptable to use exceptions instead of verbose null-checks?

Question

I recenly encountered this problem in a project: There\'s a chain of nested objects, e.g.: class A contains an instance variable of class B, which in turns has an instance v

Answer 1

Well, it depends on exactly what you're doing in the catch. In the above case, it appears that you want to call doSomething() if it's available, but if it isn't you don't care. In this case I would say that trapping the specific exception you're after is just as acceptable as a verbose check to ensure you won't throw one to begin with. There are many "null-safe" methods and extensions that use try-catch in a very similar manner to what you propose; "ValueOrDefault"-type methods are very powerful wrappers for exactly what's been done with the try-catch, for exactly the reason try-catch was used.

Try/catch is, by definition, a program flow control statement. Therefore, it is expected to be used to "control ordinary program flow"; I think the distinction you are trying to make is that it should not be used to control the "happy path" of normal error-free logic flow. Even then I might disagree; there are methods in the .NET Framework and in third-party libraries that either return the desired result or throw an exception. An "exception" is not an "error" until you cannot continue because of it; if there's something else you can try or some default case the situation can boil down to, it can be considered "normal" to receive an exception. So, catch-handle-continue is a perfectly valid use of try-catch, and many uses of exception throwing in the Framework expect you to handle them robustly.

What you want to avoid is using try/catch as a "goto", by throwing exceptions that aren't really exceptions in order to "jump" to the catch statement once some condition is satisfied. This is definitely a hack, and thus bad programming.