• 9 Posts
  • 106 Comments
Joined 3 months ago
cake
Cake day: June 2nd, 2024

help-circle




















  • Exceptions are just bad. They are a separate, hidden control flow that you constantly need to be wary of. The name itself is a misnomer in my opinion, because they’re rarely exceptional: errors are not just common, but an integral part of software development

    They may be a part of software development, but they should not be common during the normal execution of software. I once read the hint, “if your app doesn’t run with all exception handlers removed, you are using exceptions in non-exceptional cases”.

    Throwing an exception is a way to tell your calling function that you encountered a program state in which you do not know how to proceed safely. If your functions regularly throw errors at you, you didn’t follow their contract and (for instance) didn’t sanitize the data appropriately.

    Errors as values are much clearer, because they explicitly show that a function may return an error and that it should be handled.

    I disagree here. You can always ignore an error return value and pretend that the “actual” value you got is correct. Ignoring an exception, on the other hand, requires the effort to first catch it and then write an empty error handler. Also (taking go as an inspiration), I (personally) find this very hard to read:

    res, error = try_something()
    if error {
      handle_the_error(error)
      return_own_error()
    }
    res2, error2 = try_something_else(res)
    if error2 {
      handle_other_error(error2)
      return_own_error()
    }
    res3, error3 = try_yet_something_else(res2)
    if error3 {
      handle_the_third_error(error3)
      return_own_error()
    }
    return res3
    

    This code mingles two separate things: The “normal” flow of the program, which is supposed to facilitate a business case, and error handling.

    In this example, on the other hand, you can easily figure out the flow of data and how it relates to the function’s purpose and ignore possible errors. Or you can concentrate on the error handling, if you so choose. But you don’t have to do both simultaneously:

    try {
      res = try_something()
      res2 = try_something_else(res)
      res3 = try_yet_something_else(res2)
      return res3
    } catch (e) {
      // check which error it is and handle it appropriately
      throw_own_exception()
    }