[COFF] [TUHS] Re: Conditions, AKA exceptions. (Was: I can't drive 55: "GOTO considered harmful" 55th anniversary)

[Steffen Nurpmeso]

Larry Stewart wrote in
 <498576F7-6881-4176-B187-F4ACB0A42F76 at serissa.com>:
 |TLDR exceptions don't make it better, they make it different.
 ...
 |On the whole, I came away with a great deal of grudging respect for \
 |ERRNO as striking a great balance between ease of use and specificity.

From my user space point of view i never understood why there is
no dedicated hardware register / (plus) error indicating flag that
callers could cheaply and easily test.  (Maybe there is on some
processor platforms, beside a one such where errno then can be
placed in some per-thread structure stored there.  Still this
requires another dedicated return value.)

I ran away from the exceptions i got used to with JAVA to
-fno-rtti -fno-exceptions when i looked at the object output of
g++ 2.95.?, and saw in the support code they use heap memory for
this etc.

 |I also evolved Larry's Theory of Exceptions, which is that it is the \
 |programmer's job to sort exceptional conditions into actionable categori\
 |es: (1) resolvable by the user (bad arguments) (2) Temporary (out of \
 |network sockets or whatever) (3) resolvable by the sysadmin (config) \
 |(4) real bug, resolvable by the author.
  ...

Really interesting point, like SMTP and other protocols which
classify errors in categories.
Errors are one of my waving-helplessly topics, where you simply
have to let things go and where "perfection" just cannot be
achieved in real-life (or add .. as time passes by).
Often you just do not find the correct answer, with errno the name
sometimes fits, but the decade-old description does not really,
and very fast you end up with overloading (eg come to a second
ENODATA because ESRCH is something different, or reuse EILSEQ for
bogus input even though the function already used to use EILSEQ
for non-convertible output).

--steffen
|
|Der Kragenbaer,                The moon bear,
|der holt sich munter           he cheerfully and one by one
|einen nach dem anderen runter  wa.ks himself off
|(By Robert Gernhardt)