On Wednesday, May 30, 2012 11:32:00 Don Clugston wrote: > On 30/05/12 10:40, Jonathan M Davis wrote: > > On Wednesday, May 30, 2012 10:26:36 deadalnix wrote: > >> The fact that error don't trigger scope and everything is nonsensial. > > > > If an Error is truly unrecoverable (as they're generally supposed to be), > > then what does it matter? Something fatal occured in your program, so it > > terminates. Because it's an Error, you can get a stack trace and report > > something before the program actually terminates, but continuing > > execution after an Error is considered to be truly _bad_ idea, so in > > general, why does it matter whether scope statements, finally blocks, or > > destructors get executed? It's only rarer cases where you're trying to do > > something like create a unit test framework on top of assert that you > > would need to catch an Error, and that's questionable enough as it is. In > > normal program execution, an error is fatal, so cleanup is irrelevant and > > even potentially dangerous, because your program is already in an invalid > > state. > > That's true for things like segfaults, but in the case of an > AssertError, there's no reason to believe that cleanup would cause any > damage. > In fact, generally, the point of an AssertError is to prevent the > program from entering an invalid state.
An assertion failure really isn't all that different from a segfault. By definition, if an assertion fails, the program is an invalid state, because the whole point of the assertion is to guarantee something about the program's state. Now, if a segfault occurs (particularly if it's caused by something other than a null pointer), the program is likely to be in a _worse_ state, but it's in an invalid state in either case. In neither case does it make any sense to try and recover, and in both cases, there's a definite risk in executing any further code - including cleanup code. Yes, the segfault is probably worse but not necessarily all that much worse. A logic error can be just as insidious to the state of a program as memory corruption, depending on what it is. > And it's very valuable to log it properly. Yes, which is why it's better to have an Error thrown rather than a halt instruction be executed. But that doesn't mean that any attempt at cleanup is any more valid. - Jonathan M Davis
