Re:You’re better off using Exceptions
by AstralStorm on Tuesday February 04, 2020 @11:52AM
(#22237813)
Why are they a poor choice for the latter?
They have a type, make it say MissingUserException and the special place can handle it in a special way. Ensure it is a subclass of some general exception type you also handle elsewhere and you're good.
Often people throw generic exceptions instead of using the type system.
Re:You’re better off using Exceptions
by dllthomas on Tuesday February 04, 2020 @07:50PM
(#22242934)
In the latter case you will often want to pass "data or the fact the data was missing" along to other functions. With a result value (of whatever form) that's trivial. With exceptions, it's certainly plenty doable but it's messy.
Sure, it depends on the situation. In the case you outline, there could also be room for an auxiliary function like
fetch_alternatives({ preferred_resouce, second_best_resource , third_best_resource}) that would fetch them in until one can actually be obtained and throw an exception if all of them fail. Not that I am married to exceptions or anything. One should just use what is best in the situation that one is in. Actually, I think articles that claim that one language construct is better than some other language construct are quite silly. It mostly depends on the situation. Though, there also may be language constructs that are best left off deprecated, depending the language that you are using.
Some things are essential to the page we are rendering, and if they are missing we should 404.
Some things are ancillary, and if they are missing we should render a stub in their place. E.g., saying that a comment is from "deleted user".
Exceptions are a good fit for the former, where we want to unify every failure. They are a poor choice for the other case, where we want to treat each failure special.
Which case a given fetch represents is a choice that should be driven by the fetcher.