Exception/Error division in D

[Kapps]

On Wednesday, 30 May 2012 at 22:22:01 UTC, Jonathan M Davis wrote:
> On Thursday, May 31, 2012 00:01:16 deadalnix wrote:
>> Most segfault are null deference or unintizialized pointer 
>> deference.
>> Both are recoverable.
>
> If you dereferenced a null pointer, it's a bug in your code. 
> Your code is
> assuming that the pointer was non-null, which was obviously 
> incorrect, because
> it was null. That's _not_ recoverable in the general case. Your 
> code was
> obviously written with the assumption that the pointer was 
> non-null, so your
> code is wrong, and so continuing to execute it makes no sense, 
> because it's in
> an invalid state and could do who-knows-what. If there's any 
> possibility of a
> pointer being null, the correct thing to do is to check it 
> before
> dereferencing it. If you don't, it's bug.
>
> Now, it's perfectly possible to design code which never checks 
> for null
> pointers and if a null pointer is dereferenced throws an 
> Exception and
> attempts to recover from it (assuming that it's possible to 
> detect the
> dereference and throw at that point, which AFAIK is impossible 
> with segfaults
> - maybe it could be done on Windows with its Access Violations, 
> but segfaults
> trigger a signal handler, and you're screwed at that point). 
> But writing code
> which just assumes that pointers are non-null and will throw if 
> they are null
> is incredibly sloppy. It means that you're treating pointers 
> like you'd treat
> user input rather than as part of your code.
>
> - Jonathan M Davis

All code has bugs in it. It's nice being notified about it and 
all, but if you release a server application, and it crashes 
every single time it encounters any bug... well, your customers 
will not have a fun time.