Errors

throw, try, catch, finally — raising an error, catching it, and moving on.

Section 5.2 promised it: “throw ends a method as well as return does — that keyword will come in its own time.” And 6.1 had you meet a run-time error defenceless: the program fell, full stop.

Its time has come. This section teaches how to throw an error, catch it, and keep the program going — your own errors first, then the language’s.

In this section

• 8.1Throwing and catching

  throw raises an instance of an archetype; catch takes it by its exact type.

• 8.2The language's errors, and finally

  Catching what the language throws — and guaranteeing a cleanup, whatever happens.