c++0x pods and constructors

Jerry Coffin wrote:
> In article <WOOGm.1013$>,
> says...
>
> [ ... ]
>
>>> If you
>>> look at it closely, you'll see that the standard doesn't
>>> actually give any guarantees with regards to standard layout and
>>> other languages, for the reason stated above.
>>
>> 'Care to restate that reason?
>
> The bottom line is pretty simple: something like 'extern "C"' is
> really trying to give a guarantee about a C compiler, but the C++
> standard doesn't really have any control over C compilers. You can
> only accomplish something useful with 'extern "C"' by having a C
> compiler that's written to cooperate with your C++ compiler -- but
> the C++ standard can't really do anything about that, and for that
> matter the C standard really can't either.

Whatever happened with projects to bring forth a standard C++ ABI. Itanium
only?

>
>>> There may be some
>>> advanced programming techniques which depend on standard layout,
>>> but for the everyday user, the only really significant
>>> distinction is whether the class could be written in C or
>>> not
>>
>> You meant if a class could look like a struct to C, surely.
>
> I think what he's saying (in effect) is that the main time PODs
> matter or get used, is when you have a header that you can compile as
> either C or C++, and you want to have (at least some) assurance of
> compatibility between the two.

I would think that cross-platform interoperability is a larger concern. At
least with a C ("POD") struct, you stand a chance at it looking the same in
more than one machine. Not hardly so for classes (I mean with one using all
the C++ "fancy" things).

>
> [ ... ]
>
>> I'm still hoping that Mr. Coffin was right about "convenience
>> constructors" being OK. (Else I'll have to research and find out
>> why there cannot be such. I'll blindly accept the concrete "special
>> functions" as being special and reserved, but I really would want
>> to know why "convenience constructors" are a no-go, if indeed so).
>
> Yes -- to be a POD, the default ctor, copy ctor and dtor must all be
> trivial. A trivial ctor must be generated by the compiler -- any user
> defined ctor is non-trivial. Even if it's carefully written to do
> exactly what a compiler-generated ctor would have done, the fact that
> you wrote it still means it's non-trivial.

I understand all that and am accepting of it.

>
> In C++ 98/03, if you define any ctor, that prevents the compiler from
> generating a default ctor.
> If you want a default ctor, you need to
> define one, and by definition, when/if you do so, it won't be a
> trivial ctor. Likewise with the dtor, copy ctor and copy assignment
> operator.

I've probably encountered that, but I didn't "know" that. So are you
retracting your statement that "convenience constructors" are allowed?

>
> In C++ 0x, however, there's an "=default" syntax that allows you to
> tell the compiler to generate a default ctor, copy ctor, copy
> assignment operator, and/or dtor, even if you _have_ defined some
> other ctor. For example:
>
> class X {
> int data;
> public:
> X(int val) : data(val) {}
> X() = default;
> X(x const &) = default;
> X &operator=(X const &other) = default;
> ~X() = default;
> };

OK, things are looking rosie then for C++0x. A good enough reason to drop
the current lineup ASAP, IMO. Hopefully the C++0x goodies will start
trickling into compilers even before "ratification" or whatever they call
it.

>
> Now, we have a user-defined ctor that takes a value of type int that
> is used to initialize the data member -- but we also have explicitly
> defaulted the definitions of the other special member functions, so
> they remain "trivial" and the type is still a POD.

And that makes me a happy camper, cuz not allowing "convenience
constructors" is a pet peave of mine. I saw/see no reason why it has to be
without them, so now I know indeed there was no reason other than oversight.

>
> One other strange wrinkle: it's possible to create a non-trivial
> special member function using the '= default;' syntax. To be trivial,
> the function must (among other things) be inline, and the
> '=default;' must be on the _declaration_ of the function. If (for
> whatever strange reason) you choose to, you can do something like:
>
> class Y {
> // ...
> public:
> Y();
> };
>
> Y::Y() = default;
>
> You've now explicitly defaulted the default ctor, BUT the '=default'
> isn't on the initial declaration, and your definition is _not_ an
> inline function, so it's no longer trivial.

I would have assumed that the out-of-line Y::Y() would not allow "=default"!
The question becomes: Why does it?! Hehe, so Scott Meyers can right more
"Effective C++" books! (Great series by the way, but if it ever becomes
contrived... oh nevermind).

>
> [ ... ]
>
>> (Aside: Are overloaded operators fast compared to functions? I
>> don't know why that sticks in my mind. Yeah I know, I could test
>> it, but I think in the past I have and have found that. I may be
>> mistaken).
>
> An overloaded operator _is_ a function -- it just has a rather
> different name than most other functions. Overloaded operators are
> typically quite short functions, so there's a good chance that the
> compiler can generate inline code. Nonetheless, the fact that it's an
> overloaded operator does not (in itself, at least with any compiler
> I've ever seen or heard of) make any difference in whether the code
> will be generated inline. The code generation depends on the size and
> complexity of the function, not the name it's given.

Alright. Maybe long ago when that stuck in my mind I had experienced the
inline vs. online thing. But I get most of my information from books (and
lately online) and "operators are FAAAST!" sticks in my mind, so I think I
may have read it somewhere. It makes perfect sense to me that operators are
no different than functions except for the obvious syntax. Oh well, could
have been a brainfart.

dragan

James Kanze wrote:
> On Oct 31, 4:12 am, "dragan" <spambus...@prodigy.net> wrote:
>> James Kanze wrote:
>>> On Oct 29, 11:40 pm, "dragan" <spambus...@prodigy.net> wrote:
>
>> I think "aggregate" gets thrown around so much, but it should
>> probably be reserved more for implementer-level discussion
>> rather than user-level. It seems so minor relative to the
>> notion of POD (or layout compatibility! Errgh, so
>> frustrating!).
>
> Yes and no. For the user, aggregate initialization can be an
> advantage in certain cases, e.g. my examples of letting the
> compiler calculate array size. For the user, there are really
> three things which interesting:
>
> 1. Aggregate initialization: useful for letting the compiler
> calculate the size of an array, and in general for static
> data.
>
> 2. Static initialization, for avoiding order of initialization
> issues. This requires trivial constructors and constant
> expressions in the initializer; for compound types (struct's
> and arrays), the type must be an aggregate, and aggregate
> initialization must be used. (Otherwise, you must have a
> constructor somewhere, and the type ceases to be trivial.)
>
> 3. PODs or layout compatibility: mainly important with regards
> to communicating with other languages, especially C. (The
> system API is generally defined in terms of C these days.)

What about cross-platform interoperability? Write a struct here, read it
there?

>
>>>> I think POD may be the key thing for layout compatibility
>>>> with C and probably other languages. PODs no longer have to
>>>> be aggregates in C++0x: they can have constructors, just
>>>> not default or copy constructors, and no copy assignment
>>>> operator. (N2690).
>
>>> Layout compatibility is an awkward problem. C++ can mandate
>>> a certain number of things with regards to how the C++
>>> compiler lays out data, but it can't mandate anything with
>>> regards to how other languages layout data. In the end,
>>> it's a lot like the ``extern "C"'' fiasco: C++ requires a
>>> compiler to support it, stating that functions declared
>>> ``extern "C"'' must be callable from C (or something along
>>> those lines). Which is all nice and fine, but what does it
>>> mean if the platform doesn't have a C compiler? Or if it
>>> has several C compilers, with different calling conventions?
>
>> "extern C" fiasco? News to me that it was a fiasco (you must
>> be an implementor/insider, I bet)! I thought it was more like
>> "thank god we can still use DLLs in C++".
>
> Fiasco may be too strong a word, but formally, the standard
> guarantees much less than it seems to. (I certainly doesn't
> guarantee anything with regards to DLLs, for example.)

I does indirectly. "C-linkage" (is that the right terminology?) is all that
can be exported from DLLs ("sorry" to be so Windows-ish). I guess you
probably could get all that name-mangled stuff to come out of a DLL on a
single machine. You won't be selling that app to other people though, that's
for sure.

>All that
> it says (with regards to C) is ``Every implementation shall
> provide for linkage to functions written in the C programming
> language, "C", and linkage to C + + functions, "C++".'' Except
> that it doesn't specify how these "functions written in the C
> programming language" are to be compiled or linked; an
> implementation may require you to compile them using a special C
> compiler, which generates code incompatible with the system API,
> for example. And it doesn't address the issue of what to do if
> there is no C compiler for the system.

Are you being too hypothetical? I don't give it a second thought: I KNOW
that I'll always be able to call "extern C" functions in a DLL (after
LoadLibrary(), blah, blah.)

>
> At least some of the people involved with the standardization
> proceedure are aware of this weakness, although the committee
> doesn't seem to have wanted to address it. I think the general
> intent is more along the lines that IF there is at least one C
> implementation available on the platform, then the compiler must
> support linkage with one of them, and document which one, and
> what is necessary to make it work.

I seem to have missed "the weakness". I'm sure there is one if you say so.
Anyway, I feel like "extern C" and "layout" are separate. It's all good
information though.

>
> The probable reason the committee didn't address the problem is
> that it isn't one in practice.

YES! Thanks for letting me know I'm not "out of it" (a bit insecure maybe,
"out of it", no way!).

> Practically all platforms that
> support C++ have a standard C ABI,

I didn't know that. Well maybe I sorta did because I rely on it ("extern C",
"POD"). So there is a formality like the C++ ABI for Itanium for C?

> which is adhered to by all C
> compilers, and practically all C++ compilers come with a C
> compiler, and require no special steps to link C and C++. So
> the standard may not say exactly what was wanted, but in
> practice, everything works as was desired.

Interesting. Big kudos for C. But it is much easier in C to make a std ABI
than in C++. C++ should have specified one from the beginning, but too late
for that now. Live and learn.

>
> Until the day someone decides that C is dead enough that they
> don't need a C compiler for their platform.

C/Std ABI: 1 point. C++/No Std ABI: -1 point. C++ is keeping C alive!

>
> [...]
>>> If you look at it closely, you'll see that the standard
>>> doesn't actually give any guarantees with regards to
>>> standard layout and other languages, for the reason stated
>>> above.
>
>> 'Care to restate that reason?
>
> The C++ standard can't impose anything on other languages, only
> on C++.

k.

>
>>> There may be some advanced programming techniques which
>>> depend on standard layout, but for the everyday user, the
>>> only really significant distinction is whether the class
>>> could be written in C or not
>
>> You meant if a class could look like a struct to C, surely.
>
> More or less, yes. With the addition of non-virtual member
> functions, but that's about it.

k.

>
>>> ---if it could, it will be accessible from C, and probably
>>> from most other languages as well (on typical small and
>>> medium general purpose computers
>
>> That covers a lot (the most of it?) of ground, and propably
>> shouldn't be flattened.
>
> Typical small and medium general purpose computers represent but
> a small percentage of all computers.

And I know that too. I think in terms of the desktop/server space mostly as
those are the applications I am building. I wasn't thinking "what pie piece
of all computers", but rather "the desktop/server space is billions and
billions of dollars of space" (with apologies to Carl Sagan).

> I'd guess off hand that
> something like 90% of all computers are embedded systems. At
> the other end, and this is the place where I suspect most of the
> problems come, are the mainframes. IBM System z doesn't define
> everything in terms of C, at least under the traditional OS's.
> (You can also get it with Linux.) Cobol is still the
> predominant language there.

I would wager that a poll (eww.. not one of THOSE!) would show that most
readers of this ng are in the client-server (includes all things web etc.
too) space. That is, working on software that interacts with humans (rather
than controlling anti-lock brakes, etc). (Or I am a fish out of water?).

>
>>> ---I wouldn't count on it on mainframes, nor for that matter
>>> on embedded systems); otherwise, it won't be. (You may, of
>>> course, add non-virtual member functions, including
>>> conversion operators, but not constructors, destructors or
>>> assignment operators, without causing problems.)
>
>> I'm still hoping that Mr. Coffin was right about "convenience
>> constructors" being OK. (Else I'll have to research and find
>> out why there cannot be such. I'll blindly accept the
>> concrete "special functions" as being special and reserved,
>> but I really would want to know why "convenience constructors"
>> are a no-go, if indeed so).
>
> You can't add "convenience constructors" today, and I'm sure
> that Jerry didn't say that.

YOU said "today". The thread is all about C++0x. Indeed he did say that, but
not with your "today" qualifier. I'm 99.9% sure that he is correct too.

> The next version of the standard
> will allow it, I think, but only if you explicitly say you want
> the "trivial" default constructor.

That's what he restated, but the thread was about C++0x, so you are sort of
"preaching to the choir".

> And while initialization
> syntax has been somewhat unified, I still don't think you can
> get all of the features of aggregate initialization (especially
> static initialization) if you provide any constructor; at most,
> you'll be guaranteed a C compatible layout (but that's typically
> the case today, with most compilers).

I assume that too today: that I can write "convenience constructors" and not
have a worry. I just don't do it because it's not official.

>
>>> The other thing that is often important is whether the class
>>> is an aggregate which supports static initialization. But
>>> in practice, the two overlap; there are very few cases where
>>> you can use static aggregate initialization but couldn't
>>> write the class in C. (The presence of a pointer to member
>>> in the class would be an example of one.)
>
>> I should have stopped responding to your post probably after I
>> asked whether you meant the current standard or the yet-to-be
>> (draft) C++. All of a sudden, I feel like I know NOTHING!
>> Errrgh!! I think my house may explode if I start up Visual C++
>> and _I_ use it! I saw no red sticker on the box.. I got it for
>> free as a download!
>
> Unless I explicitly state otherwise, I'm talking about the
> current standard.

Well, and again, the thread is specifically about C++0x. Did you miss that
key aspect?

> There are no implementations of the next
> standard (can't be, since it doesn't exist yet), and the way
> things are going, I'm beginning to wonder if there will be any
> in my lifetime.

Now THAT is an interesting tangent. I was thinking that C++0x features (at
least a few stocking-stuffers) would be in my favorite compiler for Xmas!

>
> With regards to Visual C++, it's a concrete implementation;
> concrete implementations always give you a lot more guarantees
> than the standard gives.

What do you mean by "concrete implementation"? Did you just mean one
specific implementation? As opposed to worrying about all compilers or the
majority or average of them across all platforms and domains? I just have
some Windows apps to write.

>
> As long as you're not concerned with portability, you can use
> all of the guarantees the implementation gives. Once you're
> concerned about portability, especially about potential
> portability to systems you don't know yet, it becomes trickier.

I understand that. Hopefully that "portable everywhere" hype doesn't keep
"good people down". Which brings up another interesting (to me) tangent:
that C++ doesn't compete with other languages as much as it is in
competition with platform-specific/domain-specific solutions.

>
>>>>>> How about conversion operators?
>
>>>>> You can have conversion operators in an aggregate
>>>>> (according to the definition), if other conditions are
>>>>> met.
>
>>>> I assume in a POD also.
>
>>> A conversion operator is just an ordinary member function.
>
>> A positive note for the post to end on! At least something is
>> concrete! (Until someone says a POD can't have member
>> functions!)
>
>> (Aside: Are overloaded operators fast compared to functions? I
>> don't know why that sticks in my mind. Yeah I know, I could
>> test it, but I think in the past I have and have found that. I
>> may be mistaken).
>
> An overloaded operator is just an ordinary function with a funny
> name. The only time they might impact performance is when they
> are used instead of a built-in operator.

I believe it.

dragan

James Kanze wrote:
> On Oct 31, 4:19 am, "dragan" <spambus...@prodigy.net> wrote:
>> James Kanze wrote:
> [...]
>>>> I downloaded N2960. I like to think in terms of the things
>>>> a POD can or cannot have rather than the lingo like:
>>>> trivially copyable, trivial class, standard layout, and on
>>>> and on. In another post I wrote my understanding of what is
>>>> and isn't allowed.
>
>>> The problem is that you can't express the requirements in
>>> terms of can or cannot have.
>
>> Why is that? Is it so absolutely, or just because we are
>> talking about C++?
>
> It's because the actual requirements contain several "must
> have", not can have or cannot have.

While very abstract this subthread portion seems, you seem to be saying:
"yes, you're right, so you're wrong". Let me clarify: I said I can think in
simple terms but not or can't in C++ because C++ has to be like a
president/politician walking the fence trying to be all things to all people
and I live in Greenbough Alabama and just need a new ping pong paddle. In
short, I'd MUCH rather have a language tool that I could compare against my
checkoffs (can/cannot haves) rather than have to spend oodles of time
deciphering terms like "trivial constructor" and the complex interplay
between all the other 1250 pages of the standard. I was just explaining what
I said, but suddenly, I feel catharted!

>
>>> At least partially, you have to express them in terms of
>>> "must have": a POD must have a trivial default constructor,
>>> for example (which is not the same thing as not having a
>>> non-trivial default constructor---you have three
>>> possibilities: no default constructor, trivial default
>>> constructor and non-trivial default constructor).
>
>> But by "requirements", you mean "required by an
>> implementation", yes?
>
> No. I mean the requirements on a class for it to be a POD.

k. I'm not sure from where in your other post I quoted "requirements".

dragan

James Kanze wrote:
> On Oct 31, 4:25 am, "dragan" <spambus...@prodigy.net> wrote:
>> James Kanze wrote:
>>> On Oct 29, 4:23 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
>>>> In article <VV%Fm.41268$EU5.38...@newsfe05.iad>,
>>>> spambus...@prodigy.net says...
>
> [...]
>>> Attention: the requirement isn't that the class not have a
>>> non-trivial X; it is that it have a trivial X. Thus, for
>>> example:
>
>>> struct S { S( int ); int i; };
>
>>> doesn't have a non-trivial default constructor, but it
>>> doesn't have a trivial one either, and thus, is not a POD.
>
>> Is it still layout-compatible with C though?
>
> In practice, with most compilers, yes.

I've been way to meek about using the guarantees given by my chosen
compiler. More and more, I find myself at MSDN as my source for C++
information. What I find there is guaranteed to work because that's the
compiler I'm using. C++ isn't losing ground, it's lost the war? Has most
value in the Smithsonian?

>
> The current standard doesn't talk about "layout-compatible",

The current standard is off-topic in this thread.

> and
> no C++ standard can impose anything on the C compiler. I didn't
> see anything in N2914 (the latest draft that I happen to have
> handy) that guaranteed that a "standard-layout" class is in
> anyway compatible with C.

Hmm. I thought that was at least part of the point behind "standard layout".
But, from a purely terminological point of view, it would seem to be ripe
for bandaiding the lack of standard C++ ABI. A stepping stone for the
original oversight.

>
> On the other hand, the whole concept of "layout-compatible"
> seems to have been lifted from the C standard, and from a QoI
> point of view, I would expect that anything with
> "standard-layout" be compatible with C if the system defines a
> standard C ABI (as most do).

Any guarantee is better than no guarantee. Even Master C++er Bjarne
Stroupstrup acknowledged this point-of-quality (though somewhat
condescendingly) in a presentation he gave (available on UTube).

>
>> (I'm not sure of the usefullness of "POD" anymore).
>
> Per se, they don't have much use.

I'd say (assertively) that they do, but I'm still struggling with the
definition of such a thing.

> They do restrict the
> implementation in some ways, however, that typically allows them
> to be used in mixed language headers (headers which are used by
> both C and C++).
>
>>> IIUC, in the next version of the standard, you will be able
>>> to write:
>
>>> struct S { S( int ); S() = default; int i; };
>
>>> and it will have the required trivial default constructor.
>
>> And what will the compiler do with such a trivial default
>> constructor?
>
> Nothing. Otherwise, the constructor wouldn't be trivial.
>
>> Why does it need to enslave that thing?
>
> I'm not sure what you're trying to ask there, but if it is "why
> do we need a special syntax for this?", it's because the current
> standard says that if a class has any constructor, the compiler
> won't provide a default constructor implicitly, and a lot of
> code counts on this.

I was just wondering why the compiler needed control of that special
function. What book did I not buy or decide not to buy because I don't think
that as an application programmer I need to worry about stuff that my
employer calls "get up to speed on your technical skills on your own time so
you can bring direct/real value to the company via purposeful software
applications"?

dragan

On Nov 6, 11:21 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
> In article <1c83cc8c-9e7a-457a-bf85-
> cfd3c93ad...@b15g2000yqd.googlegroups.com>, james.ka...@gmail.com
> says...

> [ ... ]
> > It's not quite that bad; you don't need active cooperation
> > with the C compiler. You do need a C compiler, however, and
> > you need to know what it does and generates in order to make
> > ``extern "C"'' work in C++.

> I was thinking primarily of the fact that anytime the C
> compiler changes anything about its ABI, the C++ compiler
> needs to know about it and take steps to compensate.
> Fortunately, at least in most cases the ABI is fairly stable,
> so this doesn't arise a lot in practice.

Or that there are two different C compilers on the system, and
they use different ABI's. Here, too, the case should be fairly
rare, due to the fact that most OS's today define their
interface in terms of C.

> [ ... ]
> > One interesting idea that I've never seen done would be to
> > conditionally add convenience functions in the header, something
> > like:

> > struct Toto
> > {
> > // ...
> > #ifdef __cplusplus
> > void someFunction() ;
> > #endif
> > };

> > In practice, I'm sure that this will work, but formally...

> In practice, it's likely to work at least as long as none of
> the functions is virtual. A virtual function would stand a
> good chance of causing breakage though...

It would almost certainly break something.

> [ ... ]
> > Just curious, but what effect does this have on static
> > initialization using the agglomerate syntax. Can I still
> > write something like:

> > static X const table[] = { 1, 2, 3 };

> > and be guaranteed that the initialization precedes all code
> > that I've written (including code in constructors of static
> > objects)?

> I haven't studied that in a lot of detail yet, but it looks
> like there's a fair bit of new material to study.

Yes. And for various reasons, I've not been able to study much
in the last year or so,

--
James Kanze

James Kanze

On Nov 7, 6:18 am, "dragan" <spambus...@prodigy.net> wrote:
> James Kanze wrote:
> > On Oct 31, 4:12 am, "dragan" <spambus...@prodigy.net> wrote:
> >> James Kanze wrote:
> >>> On Oct 29, 11:40 pm, "dragan" <spambus...@prodigy.net> wrote:

[...]
> What about cross-platform interoperability? Write a struct
> here, read it there?

That generally doesn't work, regardless. After all, it doesn't
work for int; how could it work for a struct which contains an
int?

[...]
> >> "extern C" fiasco? News to me that it was a fiasco (you
> >> must be an implementor/insider, I bet)! I thought it was
> >> more like "thank god we can still use DLLs in C++".

> > Fiasco may be too strong a word, but formally, the standard
> > guarantees much less than it seems to. (I certainly doesn't
> > guarantee anything with regards to DLLs, for example.)

> I does indirectly. "C-linkage" (is that the right
> terminology?) is all that can be exported from DLLs ("sorry"
> to be so Windows-ish).

That's not true. I've used DLL's without any C linkage on at
least three platforms: Solaris, Linux and Windows.

> I guess you probably could get all that name-mangled stuff to
> come out of a DLL on a single machine. You won't be selling
> that app to other people though, that's for sure.

The only time name mangling is relevant is when the user
explicitly loads a DLL and requests the function name (dlsym
under Unix). In such cases, the usual solution is to have a
single factory function as entry point, and declare that (and
only that) as extern "C".

Of course, you can only load DLL's which are binary compatible.
Which means a lot of different things, on different platforms.

> > All that it says (with regards to C) is ``Every
> > implementation shall provide for linkage to functions
> > written in the C programming language, "C", and linkage to C
> > + + functions, "C++".'' Except that it doesn't specify how
> > these "functions written in the C programming language" are
> > to be compiled or linked; an implementation may require you
> > to compile them using a special C compiler, which generates
> > code incompatible with the system API, for example. And it
> > doesn't address the issue of what to do if there is no C
> > compiler for the system.

> Are you being too hypothetical? I don't give it a second
> thought: I KNOW that I'll always be able to call "extern C"
> functions in a DLL (after LoadLibrary(), blah, blah.)

If you're talking about the standard, you have to consider all
possible cases. I explicitly stated elsewhere that this isn't a
problem in practice.

Of course, if you're calling LoadLibrary, then you're 100%
Windows anyway, so you can count on the guarantees Microsoft
gives as well as those in the standard.

> > At least some of the people involved with the
> > standardization proceedure are aware of this weakness,
> > although the committee doesn't seem to have wanted to
> > address it. I think the general intent is more along the
> > lines that IF there is at least one C implementation
> > available on the platform, then the compiler must support
> > linkage with one of them, and document which one, and what
> > is necessary to make it work.

> I seem to have missed "the weakness". I'm sure there is one if
> you say so. Anyway, I feel like "extern C" and "layout" are
> separate. It's all good information though.

The weakness is that for a C++ compiler to compile something
which can be called from C, it needs a C compiler and some
collaboration on the part of the C compiler. And the C++
standard has no influence over C compilers.

And extern "C" and layout are pretty orthogonal; depending on
what you're doing, you might need both extern "C" and some sort
of layout compatibility, however.

> > The probable reason the committee didn't address the problem
> > is that it isn't one in practice.

> YES! Thanks for letting me know I'm not "out of it" (a bit
> insecure maybe, "out of it", no way!).

> > Practically all platforms that support C++ have a standard C
> > ABI,

> I didn't know that. Well maybe I sorta did because I rely on
> it ("extern C", "POD"). So there is a formality like the C++
> ABI for Itanium for C?

It depends on the platform, but for at least Posix and Windows,
there has to be, since the system ABI is defined in terms of C.
In practice, given the simplicity of C, most of the layout
issues depend directly on the hardware---I don't need to read
the compiler specifications for an IBM mainframe, for example,
to know the layout, since a compiler isn't going to introduce
unnecessary padding (it can, but it won't), and the hardware
determines where the padding, etc., is necessary.

C++ is more complicated, since you have to consider things like
how vtables are layed out. And for both C and C++, the calling
conventions can vary. I don't know the situation on modern
mainframes, but a long time ago, I know that different C
compilers for the Siemens BS2000 used different calling
conventions.

> > which is adhered to by all C compilers, and practically all
> > C++ compilers come with a C compiler, and require no special
> > steps to link C and C++. So the standard may not say
> > exactly what was wanted, but in practice, everything works
> > as was desired.

> Interesting. Big kudos for C. But it is much easier in C to
> make a std ABI than in C++. C++ should have specified one from
> the beginning, but too late for that now. Live and learn.

The language specification cannot specify a standard ABI. That
has to be hardware specific. Historically, C++ became
significant after most hardware architectures had been
specified, and there were several different C++ compilers around
before C++ became important enough. The Itanium is the rare
exception of an architecture which was defined after C++ was
important, but before any compilers existed for it.

> > Until the day someone decides that C is dead enough that
> > they don't need a C compiler for their platform.

> C/Std ABI: 1 point. C++/No Std ABI: -1 point. C++ is keeping C
> alive!

History is keeping C alive.

> > [...]
> > Unless I explicitly state otherwise, I'm talking about the
> > current standard.

> Well, and again, the thread is specifically about C++0x. Did
> you miss that key aspect?

Yes. Generally speaking, this newsgroup is about programming in
C++; there is a separate group, comp.std.c++ for discussions of
the standard. And while the separation isn't absolute, you
can't program in C++0x today, so most discussion of it probably
would be more appropriate in csc++.

> > There are no implementations of the next standard (can't be,
> > since it doesn't exist yet), and the way things are going,
> > I'm beginning to wonder if there will be any in my lifetime.

> Now THAT is an interesting tangent. I was thinking that C++0x
> features (at least a few stocking-stuffers) would be in my
> favorite compiler for Xmas!

That is, of course, completely impossible, since the standard
still hasn't been approved, and in fact, we still don't know
exactly what will be in it. Generally, it takes a few years
after the finalization of a standard for implementations to
catch up; for that matter, most compilers today don't implement
all of C++03.

> > With regards to Visual C++, it's a concrete implementation;
> > concrete implementations always give you a lot more
> > guarantees than the standard gives.

> What do you mean by "concrete implementation"?

That it's real. It exists. It's not just an abstract
specification.

> Did you just mean one specific implementation?

Yes. (I suppose that technically, it's several implementations,
since you can control some of the aspects, like the signedness
of a plain char, from the command line.)

> As opposed to worrying about all compilers or the majority or
> average of them across all platforms and domains? I just have
> some Windows apps to write.

If all you're targetting is Windows, then all you need to know
is Visual C++.

--
James Kanze

James Kanze

On Nov 7, 6:53 am, "dragan" <spambus...@prodigy.net> wrote:
> James Kanze wrote:
> > On Oct 31, 4:25 am, "dragan" <spambus...@prodigy.net> wrote:
> >> James Kanze wrote:
> >>> On Oct 29, 4:23 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
> >>>> In article <VV%Fm.41268$EU5.38...@newsfe05.iad>,
> >>>> spambus...@prodigy.net says...

> > [...]
> >>> Attention: the requirement isn't that the class not have a
> >>> non-trivial X; it is that it have a trivial X. Thus, for
> >>> example:

> >>> struct S { S( int ); int i; };

> >>> doesn't have a non-trivial default constructor, but it
> >>> doesn't have a trivial one either, and thus, is not a POD.

> >> Is it still layout-compatible with C though?

> > In practice, with most compilers, yes.

> I've been way to meek about using the guarantees given by my
> chosen compiler. More and more, I find myself at MSDN as my
> source for C++ information. What I find there is guaranteed to
> work because that's the compiler I'm using. C++ isn't losing
> ground, it's lost the war? Has most value in the Smithsonian?

I don't follow you. One of the reasons (not the only one) C++
continues to be important is because it leaves significant
liberty to the implementation. It can be implemented on just
about every platform.

> > The current standard doesn't talk about "layout-compatible",

> The current standard is off-topic in this thread.

Some abstract future standard is arguably off-topic in this
newsgroup. At least, there's a more appropriate news group for
it: comp.std.c++.

> > and no C++ standard can impose anything on the C compiler.
> > I didn't see anything in N2914 (the latest draft that I
> > happen to have handy) that guaranteed that a
> > "standard-layout" class is in anyway compatible with C.

> Hmm. I thought that was at least part of the point behind
> "standard layout".

Sort of. I suspect that the intent behind "standard-layout"
does have to do with C compatibility. But the standard can't
impose that, because compatibility is a two way street, and the
C++ standard cannot impose anything on C. In practice, I think
the intent is clear, and if an implementation provides both a C
and a C++ compiler (the usual case when C++ is present), then I
would expect, from a QoI point of view, that a standard-layout
class be compatible with C, provided that it only uses elements
of C (i.e. no pointers to members).

> But, from a purely terminological point of view, it would seem
> to be ripe for bandaiding the lack of standard C++ ABI. A
> stepping stone for the original oversight.

It would be nice if some architectures did define a standard C++
ABI. But it's up to the architectures; the C++ standard can't
do it.

> > On the other hand, the whole concept of "layout-compatible"
> > seems to have been lifted from the C standard, and from a
> > QoI point of view, I would expect that anything with
> > "standard-layout" be compatible with C if the system defines
> > a standard C ABI (as most do).

> Any guarantee is better than no guarantee. Even Master C++er
> Bjarne Stroupstrup acknowledged this point-of-quality (though
> somewhat condescendingly) in a presentation he gave (available
> on UTube).

A standard can't guarantee a usable implementation. It's never
more than part of what you count on.

> >> (I'm not sure of the usefullness of "POD" anymore).

> > Per se, they don't have much use.

> I'd say (assertively) that they do, but I'm still struggling
> with the definition of such a thing.

Per se, limited strictly to the guaranteed in the standard, they
don't. What they do is...

> > They do restrict the implementation in some ways, however,
> > that typically allows them to be used in mixed language
> > headers (headers which are used by both C and C++).

So in practice, they end up having a utility beyond that
specified in the standard.

[...]
> > I'm not sure what you're trying to ask there, but if it is "why
> > do we need a special syntax for this?", it's because the current
> > standard says that if a class has any constructor, the compiler
> > won't provide a default constructor implicitly, and a lot of
> > code counts on this.

> I was just wondering why the compiler needed control of that
> special function.

I'm not too sure what you mean by "control of that special
function". In C, it's possible to write something like:

struct S { int a; int b; };
S s;

and it was desired that this be possible in C++ as well, for
reasons of C compatibility, if nothing else. This means that
the compiler must implicitly declare and define a default
constructor, if the user doesn't. It was also felt that if the
user did define a constructor, it should be impossible to bypass
it. This gives you the rules of the present standard.

--
James Kanze

James Kanze

James Kanze wrote:
> On Nov 7, 6:53 am, "dragan" <spambus...@prodigy.net> wrote:
>> James Kanze wrote:
>>> On Oct 31, 4:25 am, "dragan" <spambus...@prodigy.net> wrote:
>>>> James Kanze wrote:
>>>>> On Oct 29, 4:23 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
>>>>>> In article <VV%Fm.41268$EU5.38...@newsfe05.iad>,
>>>>>> spambus...@prodigy.net says...
>
>>> [...]
>>>>> Attention: the requirement isn't that the class not have a
>>>>> non-trivial X; it is that it have a trivial X. Thus, for
>>>>> example:
>
>>>>> struct S { S( int ); int i; };
>
>>>>> doesn't have a non-trivial default constructor, but it
>>>>> doesn't have a trivial one either, and thus, is not a POD.
>
>>>> Is it still layout-compatible with C though?
>
>>> In practice, with most compilers, yes.
>
>> I've been way to meek about using the guarantees given by my
>> chosen compiler. More and more, I find myself at MSDN as my
>> source for C++ information. What I find there is guaranteed to
>> work because that's the compiler I'm using. C++ isn't losing
>> ground, it's lost the war? Has most value in the Smithsonian?
>
> I don't follow you. One of the reasons (not the only one) C++
> continues to be important is because it leaves significant
> liberty to the implementation. It can be implemented on just
> about every platform.

That is not important.

>
>>> The current standard doesn't talk about "layout-compatible",
>
>> The current standard is off-topic in this thread.
>
> Some abstract future standard is arguably off-topic in this
> newsgroup. At least, there's a more appropriate news group for
> it: comp.std.c++.

That's your OPINION. (Or your attempt at imposition).

>
>>> and no C++ standard can impose anything on the C compiler.
>>> I didn't see anything in N2914 (the latest draft that I
>>> happen to have handy) that guaranteed that a
>>> "standard-layout" class is in anyway compatible with C.
>
>> Hmm. I thought that was at least part of the point behind
>> "standard layout".
>
> Sort of. I suspect that the intent behind "standard-layout"
> does have to do with C compatibility. But the standard can't
> impose that, because compatibility is a two way street, and the
> C++ standard cannot impose anything on C. In practice, I think
> the intent is clear, and if an implementation provides both a C
> and a C++ compiler (the usual case when C++ is present), then I
> would expect, from a QoI point of view, that a standard-layout
> class be compatible with C, provided that it only uses elements
> of C (i.e. no pointers to members).

You said: C++ is dead.

>
>> But, from a purely terminological point of view, it would seem
>> to be ripe for bandaiding the lack of standard C++ ABI. A
>> stepping stone for the original oversight.
>
> It would be nice if some architectures did define a standard C++
> ABI. But it's up to the architectures; the C++ standard can't
> do it.

Hello. Bottleneck imposing itself .

>
>>> On the other hand, the whole concept of "layout-compatible"
>>> seems to have been lifted from the C standard, and from a
>>> QoI point of view, I would expect that anything with
>>> "standard-layout" be compatible with C if the system defines
>>> a standard C ABI (as most do).
>
>> Any guarantee is better than no guarantee. Even Master C++er
>> Bjarne Stroupstrup acknowledged this point-of-quality (though
>> somewhat condescendingly) in a presentation he gave (available
>> on UTube).
>
> A standard can't guarantee a usable implementation. It's never
> more than part of what you count on.

"If you're stupid, you vote".

>
>>>> (I'm not sure of the usefullness of "POD" anymore).
>
>>> Per se, they don't have much use.
>
>> I'd say (assertively) that they do, but I'm still struggling
>> with the definition of such a thing.
>
> Per se, limited strictly to the guaranteed in the standard, they
> don't. What they do is...

What do they do? Hmm?

>
>>> They do restrict the implementation in some ways, however,
>>> that typically allows them to be used in mixed language
>>> headers (headers which are used by both C and C++).
>
> So in practice, they end up having a utility beyond that
> specified in the standard.
>
> [...]
>>> I'm not sure what you're trying to ask there, but if it is "why
>>> do we need a special syntax for this?", it's because the current
>>> standard says that if a class has any constructor, the compiler
>>> won't provide a default constructor implicitly, and a lot of
>>> code counts on this.
>
>> I was just wondering why the compiler needed control of that
>> special function.
>
> I'm not too sure what you mean by "control of that special
> function". In C, it's possible to write something like:
>
> struct S { int a; int b; };
> S s;
>
> and it was desired that this be possible in C++ as well, for
> reasons of C compatibility, if nothing else. This means that
> the compiler must implicitly declare and define a default
> constructor, if the user doesn't. It was also felt that if the
> user did define a constructor, it should be impossible to bypass
> it. This gives you the rules of the present standard.

I don't believe you. I live in Romania and know your weak presentations.

dragan

On Nov 9, 8:21 am, "dragan" <spambus...@prodigy.net> wrote:
> James Kanze wrote:
> > On Nov 7, 6:53 am, "dragan" <spambus...@prodigy.net> wrote:
> >> James Kanze wrote:
> >>> On Oct 31, 4:25 am, "dragan" <spambus...@prodigy.net> wrote:
> >>>> James Kanze wrote:
> >>>>> On Oct 29, 4:23 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
> >>>>>> In article <VV%Fm.41268$EU5.38...@newsfe05.iad>,
> >>>>>> spambus...@prodigy.net says...

> >>> [...]
> > I don't follow you. One of the reasons (not the only one)
> > C++ continues to be important is because it leaves
> > significant liberty to the implementation. It can be
> > implemented on just about every platform.

> That is not important.

The fact that C++ can be implemented on just about every
platform is important to the majority of the committee. Some
people don't care about anything but Windows, but they're far
from a majority.

> >>> The current standard doesn't talk about "layout-compatible",

> >> The current standard is off-topic in this thread.

> > Some abstract future standard is arguably off-topic in this
> > newsgroup. At least, there's a more appropriate news group
> > for it: comp.std.c++.

> That's your OPINION. (Or your attempt at imposition).

It's not an absolute, and some discussion of the future standard
is certainly acceptable (since the future standard also concerns
C++). But in general, people who want to discuss purely
standard issues (and anything to do with the future standard is
purely a standard issue, since it is pretty much irrelevant to
programming today) do so in the group which is specialized for
it: comp.std.c++.

> >>> and no C++ standard can impose anything on the C compiler.
> >>> I didn't see anything in N2914 (the latest draft that I
> >>> happen to have handy) that guaranteed that a
> >>> "standard-layout" class is in anyway compatible with C.

> >> Hmm. I thought that was at least part of the point behind
> >> "standard layout".

> > Sort of. I suspect that the intent behind "standard-layout"
> > does have to do with C compatibility. But the standard
> > can't impose that, because compatibility is a two way
> > street, and the C++ standard cannot impose anything on C.
> > In practice, I think the intent is clear, and if an
> > implementation provides both a C and a C++ compiler (the
> > usual case when C++ is present), then I would expect, from a
> > QoI point of view, that a standard-layout class be
> > compatible with C, provided that it only uses elements of C
> > (i.e. no pointers to members).

> You said: C++ is dead.

When did I ever say that? Just the contrary, C++ is a lot more
alive than many people want.

> >> But, from a purely terminological point of view, it would
> >> seem to be ripe for bandaiding the lack of standard C++
> >> ABI. A stepping stone for the original oversight.

> > It would be nice if some architectures did define a standard C++
> > ABI. But it's up to the architectures; the C++ standard can't
> > do it.

> Hello. Bottleneck imposing itself .

In what sense? It's just common sense: a standard designed to
be implemented on many different platforms can't impose anything
which has to be specific to a given platform.

> >>> On the other hand, the whole concept of
> >>> "layout-compatible" seems to have been lifted from the C
> >>> standard, and from a QoI point of view, I would expect
> >>> that anything with "standard-layout" be compatible with C
> >>> if the system defines a standard C ABI (as most do).

> >> Any guarantee is better than no guarantee. Even Master
> >> C++er Bjarne Stroupstrup acknowledged this point-of-quality
> >> (though somewhat condescendingly) in a presentation he gave
> >> (available on UTube).

> > A standard can't guarantee a usable implementation. It's
> > never more than part of what you count on.

> "If you're stupid, you vote".

You're not making sense.

> >>>> (I'm not sure of the usefullness of "POD" anymore).

> >>> Per se, they don't have much use.

> >> I'd say (assertively) that they do, but I'm still struggling
> >> with the definition of such a thing.

> > Per se, limited strictly to the guaranteed in the standard, they
> > don't. What they do is...

> What do they do? Hmm?

What I explained immediately following the "Per se, they don't
have much use." Which still immediately follows.

> >>> They do restrict the implementation in some ways, however,
> >>> that typically allows them to be used in mixed language
> >>> headers (headers which are used by both C and C++).

> > So in practice, they end up having a utility beyond that
> > specified in the standard.

> > [...]
> >>> I'm not sure what you're trying to ask there, but if it is
> >>> "why do we need a special syntax for this?", it's because
> >>> the current standard says that if a class has any
> >>> constructor, the compiler won't provide a default
> >>> constructor implicitly, and a lot of code counts on this.

> >> I was just wondering why the compiler needed control of that
> >> special function.

> > I'm not too sure what you mean by "control of that special
> > function". In C, it's possible to write something like:

> > struct S { int a; int b; };
> > S s;

> > and it was desired that this be possible in C++ as well, for
> > reasons of C compatibility, if nothing else. This means
> > that the compiler must implicitly declare and define a
> > default constructor, if the user doesn't. It was also felt
> > that if the user did define a constructor, it should be
> > impossible to bypass it. This gives you the rules of the
> > present standard.

> I don't believe you.

So read Stroustrup's D&E. Those are exactly the reasons
(somewhat summarized) he gives.

> I live in Romania and know your weak presentations.

What does living in Romania have to do with anything? Except
maybe that English isn't your first language, so you
misunderstand some of the finer points, or misexpress what you
are trying to say---but overall, your English seems quite good?
And I don't know what you mean by "weak presentations", either.
I'm just presenting the facts as I know them. There's no effort
on my part to make a particular "presentation".

--
James Kanze

James Kanze

James Kanze wrote:
> On Nov 9, 8:21 am, "dragan" <spambus...@prodigy.net> wrote:
>> James Kanze wrote:
>>> On Nov 7, 6:53 am, "dragan" <spambus...@prodigy.net> wrote:
>>>> James Kanze wrote:
>>>>> On Oct 31, 4:25 am, "dragan" <spambus...@prodigy.net> wrote:
>>>>>> James Kanze wrote:
>>>>>>> On Oct 29, 4:23 pm, Jerry Coffin <jerryvcof...@yahoo.com> wrote:
>>>>>>>> In article <VV%Fm.41268$EU5.38...@newsfe05.iad>,
>>>>>>>> spambus...@prodigy.net says...
>
>>>>> [...]
>>> I don't follow you. One of the reasons (not the only one)
>>> C++ continues to be important is because it leaves
>>> significant liberty to the implementation. It can be
>>> implemented on just about every platform.
>
>> That is not important.
>
> The fact that C++ can be implemented on just about every
> platform is important to the majority of the committee. Some
> people don't care about anything but Windows, but they're far
> from a majority.

"Oopsies" then, I must be autistic: I thought the world revolved around
Windows! I mean, it's EVERYwhere: desktop, server, mobile, embedded. What
more is there? Is anything more ubiquitous than Windows? Why bother with
anything else? Learn one thing and be done with it, right? So what if every
stoplight has QNX controlling it? Soon it will be Windows Embedded.

>
>>>>> The current standard doesn't talk about "layout-compatible",
>
>>>> The current standard is off-topic in this thread.
>
>>> Some abstract future standard is arguably off-topic in this
>>> newsgroup. At least, there's a more appropriate news group
>>> for it: comp.std.c++.
>
>> That's your OPINION. (Or your attempt at imposition).
>
> It's not an absolute, and some discussion of the future standard
> is certainly acceptable (since the future standard also concerns
> C++). But in general, people who want to discuss purely
> standard issues (and anything to do with the future standard is
> purely a standard issue, since it is pretty much irrelevant to
> programming today) do so in the group which is specialized for
> it: comp.std.c++.

Easy solution for those who don't want to discuss such things: change the
channel (don't view the thread)! Right?

>
>>>>> and no C++ standard can impose anything on the C compiler.
>>>>> I didn't see anything in N2914 (the latest draft that I
>>>>> happen to have handy) that guaranteed that a
>>>>> "standard-layout" class is in anyway compatible with C.
>
>>>> Hmm. I thought that was at least part of the point behind
>>>> "standard layout".
>
>>> Sort of. I suspect that the intent behind "standard-layout"
>>> does have to do with C compatibility. But the standard
>>> can't impose that, because compatibility is a two way
>>> street, and the C++ standard cannot impose anything on C.
>>> In practice, I think the intent is clear, and if an
>>> implementation provides both a C and a C++ compiler (the
>>> usual case when C++ is present), then I would expect, from a
>>> QoI point of view, that a standard-layout class be
>>> compatible with C, provided that it only uses elements of C
>>> (i.e. no pointers to members).
>
>> You said: C++ is dead.
>
> When did I ever say that? Just the contrary, C++ is a lot more
> alive than many people want.

In looking to forget it's lineage but still purporting something like that.
You can't have it both ways. And when is this next standard going to be real
anyway? It needs to happen EVERY year or "yer (C++) outta here!". IMHO, of
course.

>
>>>> But, from a purely terminological point of view, it would
>>>> seem to be ripe for bandaiding the lack of standard C++
>>>> ABI. A stepping stone for the original oversight.
>
>>> It would be nice if some architectures did define a standard C++
>>> ABI. But it's up to the architectures; the C++ standard can't
>>> do it.
>
>> Hello. Bottleneck imposing itself .
>
> In what sense? It's just common sense: a standard designed to
> be implemented on many different platforms can't impose anything
> which has to be specific to a given platform.

"Bottlenecks" are those things that cue other things behind them because
they move too slowly: they impede progresss. Parallel paths are prudent and
C++ needs to be "forked" or something (like in open source development): the
backwards-compatible path (which will die off sooner than you think once the
other paths open) and the path going forward. I said that quite well,
actually, if I do say so myself. Kudos to MEEEE!

>
>>>>> On the other hand, the whole concept of
>>>>> "layout-compatible" seems to have been lifted from the C
>>>>> standard, and from a QoI point of view, I would expect
>>>>> that anything with "standard-layout" be compatible with C
>>>>> if the system defines a standard C ABI (as most do).
>
>>>> Any guarantee is better than no guarantee. Even Master
>>>> C++er Bjarne Stroupstrup acknowledged this point-of-quality
>>>> (though somewhat condescendingly) in a presentation he gave
>>>> (available on UTube).
>
>>> A standard can't guarantee a usable implementation. It's
>>> never more than part of what you count on.
>
>> "If you're stupid, you vote".
>
> You're not making sense.

It was a spoof on "designed by comittee". I think "the comittee" needs
direction.

>
>>>>>> (I'm not sure of the usefullness of "POD" anymore).
>
>>>>> Per se, they don't have much use.
>
>>>> I'd say (assertively) that they do, but I'm still struggling
>>>> with the definition of such a thing.
>
>>> Per se, limited strictly to the guaranteed in the standard, they
>>> don't. What they do is...
>
>> What do they do? Hmm?
>
> What I explained immediately following the "Per se, they don't
> have much use." Which still immediately follows.

And that's why the comittee and standard are undergoing so much revision on
the issue? Maybe I just know what I read and it is not current about what's
going on with the holy standard, but I do know that I read similar
"sentiments" to mine that make your quip "they don't have much use", well,
hogwash.

>
>>>>> They do restrict the implementation in some ways, however,
>>>>> that typically allows them to be used in mixed language
>>>>> headers (headers which are used by both C and C++).
>
>>> So in practice, they end up having a utility beyond that
>>> specified in the standard.
>
>>> [...]
>>>>> I'm not sure what you're trying to ask there, but if it is
>>>>> "why do we need a special syntax for this?", it's because
>>>>> the current standard says that if a class has any
>>>>> constructor, the compiler won't provide a default
>>>>> constructor implicitly, and a lot of code counts on this.
>
>>>> I was just wondering why the compiler needed control of that
>>>> special function.
>
>>> I'm not too sure what you mean by "control of that special
>>> function". In C, it's possible to write something like:
>
>>> struct S { int a; int b; };
>>> S s;
>
>>> and it was desired that this be possible in C++ as well, for
>>> reasons of C compatibility, if nothing else. This means
>>> that the compiler must implicitly declare and define a
>>> default constructor, if the user doesn't. It was also felt
>>> that if the user did define a constructor, it should be
>>> impossible to bypass it. This gives you the rules of the
>>> present standard.
>
>> I don't believe you.
>
> So read Stroustrup's D&E. Those are exactly the reasons
> (somewhat summarized) he gives.

I was just maybe getting tired after your previous hogwash statement... "I
don't believe you" follows directly: try to fool me once, shame on you. (Try
to fool my twice, shame on me).

>
>> I live in Romania and know your weak presentations.
>
> What does living in Romania have to do with anything?

I don't really live there. I'm from there.

> Except
> maybe that English isn't your first language,

Not hardly, but I think I do pretty well with it because I read other
people's posts and can't decipher them for go to the bank!

> so you
> misunderstand some of the finer points, or misexpress what you
> are trying to say---but overall, your English seems quite good?

I speak better in English than what I learned as an elephant. I find English
quite less demanding: know "rolling rrrrr's" and such. Spelling is pretty
hard though, but I on purpose don't use a spell checker because I don't want
people to think I am someone who I am not.

> And I don't know what you mean by "weak presentations", either.
> I'm just presenting the facts as I know them. There's no effort
> on my part to make a particular "presentation".

I have been following your posts that are in a topic that I find interesting
and you seem to have a pattern. That pattern makes me think that you are
"defender of C++" or "guaranteeing your job". ?

dragan