Re: Necessity of multi-level error propogation
On Mar 18, 6:06 am, "Tony" <t...@my.net> wrote:
"James Kanze" <james.ka...@gmail.com> wrote in message
news:5ce344b4-c4e9-4bb9-9564-32106115936a@q9g2000yqc.googlegroups.com..=
..
On Mar 14, 12:18 pm, "Tony" <t...@my.net> wrote:
"James Kanze" <james.ka...@gmail.com> wrote in message
news:b1c57e08-6c26-4bb0-b1a4-1e9326cfd03d@h20g2000yqn.googlegroups.com=
....
On Mar 14, 7:19 am, "Tony" <t...@my.net> wrote:
"James Kanze" <james.ka...@gmail.com> wrote in message
news:b96ff18b-4fcd-4434-a9bf-
" -- In constructors, where the alternative is often using zomb=
ie
states or some such. If the constructor throws, the object
isn't there, so you don't have to worry about it. Even if
constructors had return codes (and you can easily simulate
them, if you want, using out parameters), exceptions would
be preferable, because they don't leave an incomplete objec=
t
laying around."
That may be the side effect of architecting with the RAII
pattern. If instead one chooses to define construction as
initialization rather than resource acquisition (at least in
cases where errors can occur), then the above may not be a
justification for exceptions.
"It has nothing to do with RAII."
Sure it does. If you use that pattern, especially if it's the
only one in your toolbox, then your constructors or something
called in those constructors is probably going to have the
possibility of raising an exception.
"Apparently, you don't understand RAII."
Prove that. (I'll play, I'm open to learning what I don't
know).
You prove it later in your post.
" Despite the name, it has
nothing to do with constructors"
I don't believe that.
Then you disagree with the inventor of the concept, and the
generally accepted meaning.
I don't care what it got contrived to (or in your parlance,
"evolved to"?). Teach me RAII JK and what I apparently don't
know about it. I'm of course warring against it, so be able.
In sum, you've decided to reject a concept out of hand, without
even knowing what it is.
"---std::auto_ptr, for example, is a prime example a RAII, and
none of its constructors can fail."
And your point was with that what? (??).
That RAII has nothing to do with constructors.
"If you can't construct an object (for whatever reasons), that
object shouldn't exist."
"construction" is a subjective term. As I said above, your
need for exceptions to handle errors from constructors depends
on if you define "construction" to be "resource acquisition"
(large potential to raise error) or "data member
initialization" (small/no potential to raise error).
"Construction is initializing the object so that it can be used.
There's nothing "subjective" about it."
Yes there is. You are attempting to subordinate the term
'initialization', or overloading it. I'm "simple minded" (curb
all the jokes!), initialization is AKIN to zeroing integers.
It can be. It can also be other things.
" If a constructor returns
without throwing an exception, you have an instance of the
object."
"Exceptions"? What are those? Are you trying to impose upon me
a paradigm that elevates exceptions to high status? I can't
construct an object without ... a mark on my forehead?! :P
No. I'm trying to explain basic C++ to you, since you
apparently don't know it either.
"Throwing an exception from the constructor is the simplest way
to achieve that."
Avoiding the scenario seems much simpler.
Except that you can't. If you had any experience with
non-trivial applications, you'd know that.
[...]
" Exceptions aren't more "general" or more "capable"
than other methods of reporting errors, per se. "
Oh, indeed they are marketed as such. Somewhere there is a
"suggestion" that C++ exceptions are a/THE general way to
handle erros.
Not by me. I'm rather one who argues against overuse of
exceptions. I don't like the way they break control flow. But
sometimes the alternatives are worse.
" They are
different; in some cases, those differences represent an
advantage, and in others, a disadvantage."
C'mon now JK, you don't do large scale or permeating EH other
than via C++ exceptions. Admit it.
Could you translate that into English, please. And check out
some of my postings here: exceptions are for a very limited set
of circumstances. But when those circumstances are present,
they are better (or at least less bad) than the alternatives.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
Beratung in objektorientierter Datenverarbeitung
9 place S=E9mard, 78210 St.-Cyr-l'=C9cole, France, +33 (0)1 30 23 00 34