Slashdot Mirror
Bjarne Stroustrup Previews C++0x
Szplug writes "Bjarne Stroustrup has a sneak peek at the additions to C++ that he expects will be completed (hopefully) by 2009. Included are language-defined threads, optional garbage collection, some automatic type deduction, and template concepts. From the article: 'The list of current proposals is still quite modest and not anywhere as ambitious as I'd like. However, more proposals are being considered and more libraries will appear either as part of the C++0x standard itself or as further committee technical reports.'"
"C" was an unusual enough name for a language. Then "C++", which makes sense to you or I but would only mystify a non-geek. Now "C++0x"? How is that even pronounced? "See Plus Plus Zero Ecks"? Or maybe just "C...ocks"?
Names like this serve to only further mystify computing and programming among the non-geek population.
With spending like this, exactly what are "conservatives" conserving?
What I started to hate in C++/Java/C# is that there's no easy and standard-conforming way to express complex data 'inline'. Yeah, it's cleaner to make it XML and load it runtime, but there's no simple+quick way to do that either.
Hell, you can't event put known non-uniform data in C++ vector without doing it one-by-one.
fucktard is a tenderhearted description
"And C++ programming languages, we own those, have licensed them out multiple times, obviously. We have a lot of royalties coming to us from C++."
i n/0,14179,2877578,00.html
http://techupdate.zdnet.com/techupdate/stories/ma
You know where to send your royalty checks.
Thanks
Darl McBride
There's a reason why languages come and go.
I agree that ADA and FORTRAN are out and Java and Python are in, but isn't C/C++ an expection?
C/C++ have been around for many years and show no signs of going away - C++ was initially developed in 1983, while C itself hails from the early 1970s - and they're still popular to this day. And, of course, C++ "bolted on new features" to C. In fact, C++ was initially called 'C with classes'.
As far as I'm concerned, as long as C++ is "the standard language" in so many places we may as well make it not suck in comparison to other languages, which we can do by appropriating the nice features of those other languages.
Just my $0.02,
Michael
By the time he's finished with C++0x\n==%d, I bet the specification will look suspiciously similar to that of Common Lisp!
I also have come to realize that if there is one bad thing in C++ than it is this preprocessing which it inherited from C. Especially in a large project the trouble of including the right files and linking against the matching libraries becomes a pain in the ass. In this respect I would like C++ be more like Java (or TurboPascal for the matter) where interface declarations and compiled code are unified. At the moment moving around code from one DLL to another is a lot of work, while in my perception, it could have been completely transparent from the users point of view.
I do realize that keeping backwards compatibility was one of the design features of C++, and that it also determined the success of C. But as many C++ tools are now able to make use of precompiled headers, it seems that the problem should be able to be done away with.
If we want to write complex and secure programs quickly, we need better languages, and more features does not mean better.
You're an immobile computer, remember?
How about having a slashdot interview about C++0x with Strousrup? I think it would be a good forum to gain more insights about C++ and a fine possibility to allow a community (in this case the slashdot readers) to make and to vote on feature proposals.
This has really brought out the C++ haters. Still, most commercial applications, games, utilities, OS's, etc are still written in C++ (or a combination of C and C++). There is a reason for this; it is because C++ is both incredibly effective and extremely efficient. Sure, its possible to create artificial benchmarks that prove otherwise, but in te real world where performance counts, people use C++. But when they want flexibility they go for Ruby or Python or something similar. If you want outstanding applications, you use an outstanding language like C++. If you want average applications, you use an average language like Java.
But considering that lots of OSS projects like Firefox and KDE still use C++, not to mention commercial games like World of Warcraft, C++ probably does have some saving merits.
interface and implementation (both are keywords, comes from pascal) section: lets get rid of seperate header and code files. The idea is aged, inefficient and doesn't help clarity nor ease of coding.
Bit-arrays: yesyes, I know. Boost contains a class which does that. But I think it would be so much nicer if the language had that feature.
I doubt Google, Adobe, or many of the thousands of other companies depening on C++ will be throwing their code base away any time soon. Rather, they will want their C++ code to be more robust and more managable. The features the article lists all seem to do this.
(See Stroustrup's C++ Applications page for more.)
Tell me about it! And those fancy editor thingamajiggs? A-phoooey! Real Programmers use cat(1) and do it right the first time!
sudo ergo sum
C++ is a tremendously type safe language, to the point where every time I work with it I feel like about 90% of the work I do is in accounting for type. Most of that work is thrown away after the code has been compiled, too, but it does make for a rock solid program if you do it right. It seems to deliver on a lot of the promise of ADA, really. If they can improve access to its features without compromising that type safety, I'm all for it.
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
What would you prefer - Stroustrup does it all single-handed?
It might be nice if he could.
Stroustrup lives in a fantasy world where the only reason C++ isn't as fast as C, or produce as small of assembly as C is because of the compilers- which he conveniently disavowes responsibility for.
Compare to Objective-C: You'll note that these new C++ "concepts" feature are extremely similar to Objective-C's "protocols"- only not only can a moderate programmer produce a fast Objective-C compiler, they'll know exactly where it can be slowed down and why.
It'll also already be able to do these things in C++ that are so new and innovative.
Meanwhile, some C++ compilers can make "cout << 1 << endl;" slow- and others only do it when the programmer tries to make their own "cout" like device.
If the libraries were lumped in with the core language, C++ would be a much less flexible and less appropriate tool for those kind [systems programming] of tasks.
No, it's if those libraries imposed greater responsibilities on the runtime. As it stands, the C++ runtime already has an awful lot to do- albeit less than Java or Objective-C.
Worse still: The C++ runtime isn't a peer to your own code as it is in Objective-C: With Objective-C you can interact with the runtime as if it were regular library calls.
C has a mountain of library code available, and the functionality of that library code drives new extensions to the C core language (TLS extensions, for example)
But then, C has almost zero runtime (and if you reject certain extensions: it actually has no runtime), and that's what makes it suitable for systems programming.
I don't think C++ is now, or ever was (or with the way these "extensions" keep showing up) - or ever will be suitable for Systems Programming.
Because the C++ programmer infrequently can understand what his runtime is doing- and is not encouraged to know the interface by which C++ does it's magic (because nobody knows- they're still trying to figure out how to make some C++ magic work in a way that isn't slow)- a C++ systems programmer needs a C++ runtime. Nobody has one in systems-space, so the C++ programmer (which isn't a programmer of C++) needs to write it.
The inventor of C++ can't even do this, but any moderate programmer could do this for Objective-C.
It is good for a language to have threads "built in". As mentioned in this paper, "Threads Cannot Be Implemented as a Library": http://www.hpl.hp.com/techreports/2004/HPL-2004-20 9.pdf
if you do threads in a library, you run into problems with semantics or performance. Semantic problems == compiler breaks your multithreaded program. Performance problmes == compiler does naive translation of program, terrible performance.
http://www.thebricktestament.com/the_law/when_to_
Translation : C++ will continue to be a highly useful language, as long as some other sucker does all the hard work.
Well, the power of most languages is in the libraries anyway. What is Java or C# without the standard libraries? I program in C++/Qt and rarely if ever touch all that is ugly about C++. The very few places I allocate memory myself for operation with other code I check it rigorously, Qt objects handle themselves. I use QString and QBytearray and never have issues with zero-termination or buffer overflows. Signals and slots will never crash on a dangling pointer. The new Qt4 containers with foreach are brilliant. So yeah, core C++ may be functionally poor but if you need the equivalent of java or C# it's a library away.
Kjella
Live today, because you never know what tomorrow brings
http://www.mozillaquest.com/Linux03/ScoSource-02_S tory03.html
"C++ is one of the properties that SCO owns today and we frequently are approached by customers who wish to license C++ from us and we do charge for that. Those arrangements are done on a case-by-case basis with each customer and are not disclosed publicly. C++ licensing is currently part of SCO's SCOsource licensing program."
Thanks
Blake Stowell
300+ lines of Visual C++
If you're right, WTF would you want to use a MS product? You can do a hello world in C++ with just 3 lines (TUI) or 12 (GUI with QT).
Concerning XML-based GUI descriptors, it is in general not smaller. It is smaller to define and place the components but things goes wrong when you have to manage events. In fact, from my experience, a GUI in HTML+JS, C++/QT and Java/Swing has more or less the same number of SLOC.
Million Dollar Screenshot
> And reference variables?
There is no such thing as a reference variable, you clearly don't know the C++ language. references are not variables. references are newly defined identifiers that refer to an object that already has identifiers referencing it, they don't change, ever, hence are not variable... But I see that you *really* meant *pass* by reference, if you want to ensure that the function can have no side effects, cast the parameter to const. Otherwise, if you expect to write software without knowing what the functions do, you should not be writing software.
BTW, when you say "fancy allowing standard operators to be overloaded" I think you mean "overrided". C has overloaded operators (+ is defined for int, char, short, long, float, double, etc). overriding lets you tell the compiler how to do addition for your custom bigint library, or whatever. You can misuse operator overriding, or you can misuse macros, each are there for a purpose, and each get misused by bad programmers.
> And now garbage collection? That just a feature to fix poorly written code.
No it isn't, it is a feature to simplify the determination of object lifetime when that lifetime depends on complex (or more likely, merely chaotic) runtime factors. Bad programmers use it to fix poorly written code. Sure, every lifetime can (maybe) be determined by some complicated equation, but when you have limits on how much CPU you can use and limits on how much time you can spend on maths, you use garbage collection.
The trick is only to use garbage collection when you know that you need it and what it means. There's the problem with most dynamic languages.
Why do they want so many years to decide on so simple things that are other languages take for granted for more than 15 years now? Let's see what they have in store:
But what makes the most negative impression is the willingness to recognize that the programming language world has made huge steps in the last few years, and C++ is light years behind. Here are some of the negative points, in random order:
Bjarn says he wants to make C++ an even better systems programming language. The way to do this is apparently by adding features to a language already groaning under the last batch, far from all of which have been consistently implemented in all (or even a majority of) compilers. None of these features seem to address the fact that as a systems programming language, C++ has most of the same shortcomings as C, while adding a few of its own:
1) It is no more portable than C. In particular, various fundamental data types are still dependent on the underlying CPU architecture for their size and format, leading to copious macro #ifdef sections in low-level code that must run on a variety of different systems.
2) Use of the extra abstraction mechanisms provided by C++ tends to result in code that is both larger and less performant. This is not a desirable attribute in a systems programming language.
3) It is already an extremely complex language that requires an extremely complex compiler to implement it. This makes it very difficult to validate, thereby rendering it useless for whole classes of systems programming tasks (e.g. high-reliability embedded systems).
4) The language is a mine-field of ambiguities, overloaded meanings, and counter-intuitive default behaviours that conspire to make it incredibly difficult to learn properly. There are so many potential pit-falls that even very experienced programmers from other languages have trouble writing high-quality code with it, meaning that the language is actually a source of problems in many projects rather than a mechanism for solving them.
It is thus not (as Bjarn claims) a "better C", at least in a systems programming context, because nearly everything it adds is largely superfluous to systems programmers, and comes at a cost that they are unwilling to pay. This is especially true in what is by far the largest segment of systems programming, i.e. embedded systems, many of which are programmed in _significantly simplified_ versions of C, not the goya-esque monster that is modern C++.
NB: it is very difficult to design a single language that is equally useful for both high-level applications programming and low-level systems programming because they have fundamentally different requirements. Systems programmers require precise control of minutiae, whereas applications programmers want something that lets them churn build quality end-user systems with a minimum of pissing around. C++ falls between these two stools, adding nothing useful to C's systems programming capabilities, while being so concerned with nit-picking minutiae that writing high-level applications in it is like scrubbing a very big floor with a very small toothbrush. It is IMO well-suited to only one notable application domain: games development, which is unusual in requiring a mixture of both low and high level code.
I'm not going to change your sheets again, Mr. Hastings.
There are many C++ GUI libraries, but I'm afraid that they all share a common weakness: the lack of reliance on the standard C++ library. Except maybe gtkmm, but how well is this library supported?
All the frameworks I know tend to use their own string class, their own containers, etc -- and obviously as well their own threading library.
Huh?!? C++ is a tremendously type dependant language, which is a very different thing from being type safe. If you type x = y * 3; where x is an unsigned integer and y is a float, a "type safe" language would generate a type-mismatch error at compile. A "type unsafe" language (like C++) would auto-cast without telling you and leave you scratching your head for hours trying to figure out why the results are not what you expected. Yes, that's a programmer error, but a good language should be designed to catch programmer errors at the earliest possible point (compile time).
Support Right To Repair Legislation.
As far as I can see:
./ discussion were about the new features of C++0x instead of the old "C is better than C++", "python is better than C" and "x86-assembly beats the pants off both".
1) people complaining here about C++ or its will-be features either aren't C++ users or don't understand much of C++;
2) people who have at least managed to RTFA to the end are complaining about new features of the _language_, that will be _few_, while the biggest efforts will be oriented towards extending the STL, which is the really important part.
Btw, only a C user that understand C++ poorly could complain about references. If you find yourself at ease with C, by all means, use it. But don't spit on another well engineered language without the necessary knowledge to do so.
By the way, about references: what's so different when passing to a C function a pointer to a struct, instead of a reference to a C++ one? Don't you have still to read the prototype to know you must pass a pointer indeed? There's just one small difference between C and C++: guess what, if the prototype is a const reference in C++ you've more guarantees the object won't change than with a const pointer in C, since C++ enforces constness. And you don't even have to worry about pointers referencing to free'd memory.
It would also have been nice if this
Oh, well: it's Slashdot after all. What was I expecting. Sigh.
42.
While C++ is more strongly typed than C, C++ is not type safe. Type safety means that the language ensures that no operation will ever be applied to a variable of the wrong type. However, C++ supports the ability to access arbitrary memory locations, allows type casting, and automatically converts types in many instances. Java is more strongly typed than C++, as it doesn't allow access to arbitrary memory locations, but it also supports casting and automatic conversions, and so is not type safe. If you want type safety, try a language like Ocaml or SPARK Ada.
Sorry for rather long and muddled post, and also for my poor English... Also, if you have allergic reaction to Lisp advocacy, don't read any further.
Some years ago when I had some spare time I was struggling a lot trying to make C++ a better language. I was trying to reinvent reflection, easy serialization, extend metaprogramming facilities and so on. My hopes were mostly in http://www.boost.org/">Boost C++ libraries.
At some point I've decided to try to write some extended metaobject generator, like Qt's moc, but friendlier to "modern C++", using GCCXML. In addition to generating reflection info, I was thinking of generating proxy classes and other stuff like this.
Among other things I've tried to do some of XML translation work using XSL (i.e. XML AST from GCCXML -> some more AST convenient XML representation -> (transformation) -> resulting metaobject AST. I've discovered some interesting things about XSL, e.g. that it's possible to "emulate" iteration (which is somewhat lacking in XSL) with recursion. Nevertheless after a few days of fighting with XSL I've decided to try some language which is more suited for processing various trees. Of course, when C++0x is ready, I thought, it will be the best language in all respects, including tree stuff, but as of now, STL+boost::lambda+whatever is still somewhat quirky (for instance, look at those 10 pages long error messages when you make a typo). So, although I was heavily influenced by standard myth-based mindset concerning Lisps (slow, interpreted, purely academic, "lost in a sea of parenthesis" and so on) I've decided to give Scheme a try, as I've heard that it can be used as a better XSL.
After playing with Scheme for a while, I've found out (to my surprise) that the language can be used for many other purposes besides list (tree) processing and simple scripting (as in Gimp). As an example, there are wonderful things like Scsh. It's possible to write Web applications, many Schemes can do OO. My deep respect to C++ (The Most Powerful Language Ever) began to fade, albeit slowly.
So I've begun to try to do some real things in Scheme. Disillusionment has come rather quickly due to the fact that a lot of critical stuff in Scheme (e.g. OO and packages) is not standardized and thus is 100% non-portable between implementations. Moreover, every implementation has its bugs and limitations, and when you come to the point when you need to change your implementation you discover that most of your code needs to be rewritten from scratch.
I was nearly ready to continue developing my "metaobject generator", pushing Scheme's role back to "better XSL". But something made me try Common Lisp before doing so.
What quickly became apparent to me from my CL experience is that most of problems Boost guys are fighting against are just plain nonexistent for Lispers. Look at this, for example: variant.hpp. A good workaround for C++ typing model. What do we have in Common Lisp?
(sorry for mangled indentation)
Now look at this beauty: boost::lambda. Don't forget error messages it produces when you mistype something or stumble across a bug. CL example?
Not to mention Lisp's GC versus boost::shared_ptr.
OK, these are areas where dynamic languages like Perl, Python and Ruby, and even statically typed like C# or Java are catching up to some degree. Now let's look at some CL's more-or-less unique features.
You bring up an excellent point about the rigidity of C# generics constraints. One of the crucial features of the proposals for concepts in C++ is retroactive modeling, which allows you to adapt to the specific syntax of a concept *without* changing your data type. So the problem you mention for C# generics is not actually a problem with C++
// the type of values on the stack
concepts.
Here's an example. I'm writing a concept for a Stack, which might look like this:
template
concept Stack
{
typename value_type = S::value_type;
void push_to_top(S& s, const value_type& value);
void pop_from_top(S& s);
value_type& get_top(S& s);
bool is_empty(const S& s);
};
I picked some silly names on purpose. Now, std::stack doesn't match the syntax of this concept. So what if we try to pass a std::stack to a function like the following, which expects something that is (we use the term "models") a Stack?
template
void clear_stack(S& s)
{
while (!is_empty(s)) {
pop_from_top(s);
}
}
It's going to fail to compile, because std::stack does not match the syntax of the Stack concept. If C++ concepts had the same restrictions as C# generics in this regard, we would be stuck writing an adaptor class. Yuck.
Retroactive modeling saves the day. We can fix the problem by writing a model definition like this:
template
model Stack >
{
typedef T value_type;
void push_to_top(std::stack& s, const T& value) { s.push(value); }
void pop_from_top(std::stack& s) { s.pop(); }
value_type& get_top(std::stack& s) { return s.top(); }
bool is_empty(const std::stack& s) { return s.empty(); }
};
In this model definition, we're meeting all of the requirements of the concept by providing function definitions that transform the syntax of the Stack concept (pop_from_top, is_empty, etc.) into calls to the std::stack itself (see the function bodies). Now, when we call clear_stack() with a std::stack, it "just works": the calls to is_empty() and pop_from_top() in clear_stack() go through the model definition. Of course, if we picked more standard names and member functions in our Stack concept, the model definition could be empty or (for implicit/structural concepts) omitted entirely.
Retroactive modeling is *really* important for making it easier to reuse template code. You won't need to be paranoid about matching syntax *exactly* with every concept you need to model, because the compiler will detect any mismatches and you can fix them through a model definition---without having to change the data types, templates,
or concepts. Of course, people will still try to agree on names and concepts when possible, because it saves typing. You can check out the actual proposals before the C++ committee (references follow) for more information. There are two active proposals, but the groups are working together, so expect a final "combined" proposal in the future.
There are other differences between C# generics and C++ concepts. Before starting to design concepts for C++, most of the authors of one of the concepts proposals (N1849; see below) did an extensive study of the generics facilities of several languages (e.g., C# generics, Java generics, Haskell, ML functors, C++ templates). They ran into trouble with every language they tried, and we designed our C++ concepts to avoid those problems. Here's the original paper; there's an extended version (with more languages and more detail) under review:
Ronald Garcia, Jaakko Jarvi, Andrew Lumsdaine, Jeremy G. Siek, and Jeremiah Willcock. A Comparative Study of Language Support for Generic Programming. In Proceedings of the 2003 ACM SIGPLAN conference on Object-oriented programming, systems, languages,
From my experience using C++ in the field, I basically agree. While type safety can be a headache, there are many errors that strong typing eliminates entirely, almost to the point that "if it compiles, it's correct".
If you were talking about ML, you might be right, but in the case of C++, that's unadulterated bullshit. C++ can never approach the "if it compiles, it's correct" ideal because it allows unsafe memory operations. I recently worked on a large C++ code base that "compiled" the day I arrived. Within a couple of months, I had fixed about 90 memory handling bugs, which type safety did absolutely nothing to guard against.
Erlang.org: wow
Blocks are just anonymous functions with closures, so ruby and python are equals? But python doesn't have proper first class anonymous functions with closures. It only has a half-assed crippled version that is supposedly being removed in python 3. So clearly python is missing functionality that languages like ruby and pike have.
They don't have writers the caliber of Guy Steele or Kent Pitman, so it'll still read like gargling razor blades
Their legacy syntax straightjacket will insure the code stays verbose and hard to read. Compare:
struct ltXMLCh {
bool operator() (const XMLCh* s1, const XMLCh* s2) const
{
return XMLString::compareString(s1, s2) 0;
};
};
with
#'string<
or (comparing apples to apples):
(lambda (s1 s2) (declare (string s1 s2)) (string< s1 s2))
To a Lisp hacker, XML is S-expressions in drag.
No one has used C++ for any major operating system,
t ml
Windows XP, NT, 9x. See: http://public.research.att.com/~bs/applications.h
and no one has used C++ for any hardcore military project.
I'd beg to differ.
-everphilski-
I can't understand why so many programmers stick with C++. It's just not a very good language.
That may be true (subject to debate). But the main reason is that it's everywhere. It spread and support is simply unmatchable. Even a huge corporation like Microsoft, trying to push an alternative (.Net) has a tough time making a dent in C++. Whatever shortcomings C++ may have, it's already here, everywhere, and it's not that bad as to provoke mass migration.
i ate crayons when i was a kid and now i have two braincells and the blue ones taste nicer
I agree that ADA and FORTRAN are out and Java and Python are in, but isn't C/C++ an expection?
As someone who's been paid to program in each of those over my career, I'd say that each of them have their places.