Re: Exception Misconceptions: Exceptions are for unrecoverable
errors.
In article <51cd1818-1da8-4461-899b-c4912dd1add8@b32g2000yqd.googlegroups.com>, James Kanze <james.kanze@gmail.com> wrote:
On Dec 23, 12:45 pm, ta...@mongo.net (tanix) wrote:
In article <hgskgk$kc...@news.albasani.net>, Vladimir Jovic
<vladasp...@gmail.com> wrote:
James Kanze wrote:
On Dec 22, 4:55 pm, Kaz Kylheku <kkylh...@gmail.com> wrote:
On 2009-12-22, Vladimir Jovic <vladasp...@gmail.com> wrote:
Stefan Ram wrote:
[snip]
More elegantly? Actually, for correct and secure C++
code, all functions need to be written to be =BBexception
safe=AB, but only a minority of C++ programmers does so or
even is aware of it.
Why?
The above is false. Exception-safe code is needed to write
code that avoids resource leaks in the face of an exception.
It's need to write code that is correct in the face of an
exception. What "correct" means depends on the application
specifications. (On the other hand, what he wrote is false
in so far that if the function calls no other function, or
only calls functions guaranteed not to throw, it doesn't
have to be exception safe.)
Ok, I forgot about that. Thank you.
But how many people are adding what exception can a method
throw in it's declaration? (forgot how it is called. Is it
exception declaration?) All normal coding styles are telling
that is causing more trouble then it helps.
First, many people do use "throw()" when a function cannot
throw. But that's beside the point: when you're writing code,
you do have to know whether the function can throw or not;
whether this information is provided by a language construct or
the documentation is really irrelevant.
Well, I use throw() as a matter of practice.
In YOUR language, it becomes a part of "program logic".
In MY language, it becomes a part of your defense system
against ANY kinds of most unpleasant errors.
Even if I open a file that does not throw, and I detect
an error opening it, I may throw() myself. Because I know
the higher levels have a catch that catches ANY kind of funk,
and it KNOWS what is the logical meaining of ANY ot those
throws in bulk is.
On lower level, I may not even be able to formulate a logical
error. Because I do not even know who the hell is doing what
while they are calling me to deal with this file.
So, what is the point of me reporting: "error: could not open file"?
Not much. Because you could not open it doing what?
You might be opening tens of files, and some of them may
be functionalli similar. But what is the CONTEXT?
You see?
So, this IS the case where your throws and exception mechanism
becomes a direct part of your program logic, and I mean HIGHER
level logic than simply ifs and buts of some routine.
For instance:
{
char *p = new char[256];
f();
}
If f throws an exception, this statement block is
abandoned, and the allocated memory is leaked.
Or not. If the application is using garbage collection,
it's not leaked. If the application immediately terminates
(and is in a hosted environment), it's not leaked.
Not many people are using GC :P
I recall seeing some articles on gc issue in C++ a while back
on this very group. Do not remember what it was.
But what can I say out of my own experience with Java is this:
A well written GC is such a help, that I can not even see the
argument of not implementing it to this day.
I agree,
Cool. So GET TO WORK, you high tower priests!
:--}
but you can't loose sight of the fact that Java and C++
are two different languages.
So what?
Garbage collection is nice in C++:
it definitely makes it easier to write correct code in a lot of
cases, and it is essential for safety (no dangling pointers) in
others.
Cool, so wire it into language on a level of a spec
and STANDARD functionality.
But it isn't nearly as essential in C++ as in Java,
Wut?
because C++ supports value semantics. Which mean that you don't
use nearly as many dynamically allocated objects, and most of
the ones you do use have deterministic lifetimes anyway. (Of
course, the safety issue still stands.)
Well, to tell you the truth, I do like java in this respect
better.
There is no such things as -> in java.
Everything is bla.bla.blah.
So, if you need to extend your code, you don't have to worrry
about replacing the -> notation to . notation in some instances,
which may take hours for you if you change your objects and
create some super objects than include those, etc.
Secondly, I don't have to worry about "value semantics".
I could care less if it exists. I don't have to add THIS
level of ganularity, which only creates more complications
at the end.
Just look at some "improvements" in C++, like references?
What the funk are those?
Nobody can even agree on how some compilers interpret it.
You can not assume ANY semantics if you use references.
I did not watch the C++ development for years now.
But I just have an intuitive feeling that what you guys
are doing is everything you can to kill the language.
The amount of complexities you introduce and the amount
of visible, tangible benefits they produce as a bottom
line is just WAY too lil bang for a buck.
Jeeez. I bet they are going to jump at me in bulk now!
:--}
I think language is moving in a totally dead end direction.
Again, look at the experience of Java.
Do you think, in your clear mind that it was just a waste?
That the whole Java thing is nothing more than a bad joke?
I'd think REALLY hard before answering this question.
And what do YOU guys do?
Well, just IGNORE it all, like it is some "terrorist" camp,
like some "evil" Saddam.
Instead of learning from it and appreciating that grand
piece of work called Java.
What do you learn from Php or Python, or even stinky
Javascript, as screwed up as it it?
ANYTHING?
Well, you, hight tower priests, could care less those
languages exist, because to you, "purists", those are
not really languages. Those are just toys for infantiles.
Meanwhile, more and more of the most significant development
is being implemented every single day using the Php, Python,
Ruby, Javascript, SQL or even that HTML, NONE of which has
the kind of portability problems C++ has.
Do you see ANYTHING?
Or you are blind, sitting in that fortress of yours,
in that high tower of yours, hoarding the "secrets"
of the "craft"?
I just bet you, the significance of C++ is going to be diminished
to the point, where it will become an atrophied organ in the
body of modern world, and information processing specifically.
And information processing is probably the most critical
aspects of the entire mankind's development and survival.
Because things need to happen URGENTLY now and at a rate
never seen before in the entire history of mankind.
By the time those monsters, aka politicians, keep hoarding
some of their "private interests" and making some deal
as far as environmental situations goes, that are simply
insane, we need the information machine to work as smoothly
and as efficiently as we can manage.
And that is YOUR OBLIGATION. It is not longer a luxury,
or some game you play when you have nothing better to do.
So, the VAST majority of programming nowadays better be
directed towards information processing.
TOTAL portability is a MUST from now on.
I do not want to hear the type of arguments I keep hearing.
Not that it matters to me personally more than a dead
mosquito fart.
I want to see C++, if it EVER has a chance, to run
on ANY platform and I want to see a GUI wired into the
language. Sure, you don't have an equivalent of JVM,
so you can not rely on things it provides you.
Well, but WHO prevents you from having something of
that kind or even going as far as starting out with
using the existing JVM? After all, how was C++
initially implemented?
Ask Strousrup.
And I did, and he lied.
At Ruben Engineering, Cambridge, Mass. USA.
Because I asked him this:
"why did you implement C++ as a preprocessor to C?"
And he said:
Nope. It is NOT a preprocessor.
And it is a lie.
Because it was literally a fancy preporocessor.
Because after the 1st phase of "compilation",
it simply ran the C compiler.
Ask him.
And what about those "objects" and how the first versions
of C++ were linked?
Well, the stuff was PATCHED in your executable,
just to make C++ behavior out of standard C exectutables.
So...
Why don't you hack something up that can help to save
this dinasaur called C++?
Ok, enough for now.
Cya.
I bet you can not even imagine how much times was wasted to
date by the programmers to deal with this totally stoopid
issues related to memory deallocation. Probably at least 30%
of total time spend on developing the C++ code.
Generally less than 10% of the time. But given the cost of
competent engineers, even 10% is worth it.
C++ would probably be benefited tremendously if it adopted
some of the central Java concept, such as GC, threads and GUI.
Except that would require an equivalent of a virtual machine
underneath.
Not at all. I've used garbage collection in C++, and I've used
C++ in multithreaded programs. And a lot of people have written
GUI's in C++. All without a virtual machine.
All would be nice additions, IMHO, although for various
reasons, I don't think a standard GUI would be possible today.
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