Stroustrup on the Future of C++ 661
/ASCII writes "Bjarne Stroustrup, the father of C++, has written an essay [PDF] on the features of the upcoming C++0x standard. In his essay, he argues that new features should whenever possible go into the standard library and not into the language, but that the language needs to shave of a few rough corners to make it easier to use for novices."
wait a moment... (Score:5, Funny)
Re:wait a moment... (Score:5, Funny)
Not when it's God talking.
Re:wait a moment... (Score:4, Insightful)
Speaking of which, did anybody else notice the author description in that article?
"Bjarne Stroustrup is the College of Engineering Professor in Computer Science at Texas A&M University"
What!? Isn't that like saying the George Bush is a businessman from Texas? It's technically true, but completely misses the point on what matters.
This makes even less sense when you try to find the target audience. If the person reading the article already knows who Bjarne is (by which I mean every single C++ programmer), then I could see them omitting the entire "creator of C++" description because, well, they already know... but then why have a description at all?
If the person doesn't already know who this "Bjarne" is and they are reading the article, don't you think they'd want to know that he created the thing and therefore might have some relevant opinions on that matter?
Very odd...
Re:wait a moment... (Score:4, Funny)
I don't know... don't most people prefer to emphasize their accomplishments and hide their failures?
Blasphemy? (Score:5, Funny)
Now, what an academic is doing having a successful programming language with real-world applications is another question...
Re:wait a moment... (Score:2)
Re:wait a moment... (Score:3, Funny)
Re:Waiting for C++ 2007 lite ANSI standard (Score:3, Insightful)
Dynamics in programming languages (Score:5, Insightful)
Re:Dynamics in programming languages (Score:5, Informative)
If you find that interesting, you're going to love Stroustrup's The Design and Evolution of C++.
It's an almost novelistic discussion of how he made C in to C++, the various trade-offs required, and how he decided what changes to make or not make. For example, why the dot operator (".") can't be overloaded, but the parentheses can be, and why (contra Goslings Java) operator overloading is a good thing (short answer: it makes syntax match semantics).
If you ever want, or need, to develop a large-scale, flexible and general system of anything (and what's more general than C++, a programming language used by millions to write both Object Oriented and just "better C" code?), D&E is a wealth of experience, carefully and fully explained.
And, like a novel, it's for the most part a fun read. Grab a copy, and you'll not only understand C++ better, you'll understand why C++ is what it is, and how it got there from C.
"Design and Evolution" mis-titled (Score:5, Interesting)
It's a good, informative read, though not always a fun one - I still gnash my teeth every time I read about how they settled on termination semantics for exceptions.
Re:"Design and Evolution" mis-titled (Score:3, Interesting)
a 'few' rough edges (Score:4, Insightful)
Re:a 'few' rough edges (Score:2, Funny)
Re:a 'few' rough edges (Score:5, Interesting)
So tell me, what really is wrong with C#?
Re:a 'few' rough edges (Score:3, Informative)
C# is not standard. Yes I know there is a standard specification, but it's not an "industry standard" in that it's not supported widely. E.g. can I simply compile my C# applications on OS X in Xcode, or on Linux, even if I have used cross-platform libraries like wxWidgets? As an ISV, choosing C# would mean a choice to deliberately limit the available platforms we could run our software on. This doesn't make sense at a time when libs like wxWidgets make it easy to develop decent cross-platform software - the
Re:a 'few' rough edges (Score:3, Insightful)
You appear to miss the point. It may very well be slow, and probably is, but it is slow at compile time, and generates the fast table for you to use at run time.
In practice, I've written some knarly templates, and have not found the compile speed to be all that bad.
Re:a 'few' rough edges (Score:5, Informative)
Java does not remove a few warts from C++, it forces you to use a Garbage collector, OO design, type introspection, etc, etc. Those are pretty fundamental changes.
Re:a 'few' rough edges (Score:4, Insightful)
Point of fact stays however: c++ has an enormous learning curve. Complexity in the language is imho comparable to Latin: you can almost recognise the author by lookin at the code. That complexity is far, far less in java.
Especially the gc makes life a lot easier for even seasoned programmers.
And by the way: you can be almost as un-OO in java as you can be in c++. Introspection in java is mostly used in 'frameworks', like for instance the serialization API; normally you almost never use it.
Re:a 'few' rough edges (Score:3, Informative)
Re:a 'few' rough edges (Score:3, Insightful)
Now getting back to C++, you are not forced to do anything except write code like the following:
T & list::iterator::operator* () const
{
return current->data;
}
Yeah I suppose this is obvious, and simple! (NOT)
I completely gave up on C++ about six months ago. Before that I was half in and half out. Having read BS's article I have to say I am glad I gave up on C++.
I have talked to multiple people who regularly develop using Pyth
Re:a 'few' rough edges (Score:3, Interesting)
I'm not so sure about 'auto'. Just from the article, which admittedly is not supposed to be a list of features going into the new standard, I can't help but see problems. e.g.:
auto my_thing = [complex stl expression];
[some other complex expression](my_thing);
and getting some horrible STL error on the second expression because the type of the first expression wasn't what you expected and now you have to figure out what it actually was and how to fo
Re:a 'few' rough edges (Score:5, Insightful)
Java's ok, but a few mistakes were made. Among the worst: over-reliance on the instanceof operator, and the need for something called a MethodNotSupported exception.
Now think about what MethodNotSupported means in the context of Barbara Liskov's Substitution Principle:
We've got a language that supports inheritance. Inheritance makes sense only insofar as Liskov's Principle is followed. Put simply, if class D inherits from class B, any "promises" that B made -- it's interface, both syntactically, in terms of public member names, and semantically, that the member functions really do do some particular thing -- any of those promises must also be kept by D, because we are saying, as Liskov tells us, that D is-a B.
If I hand you an instance of D, and you plug it in place of am instance of B, anything that the B instance does, the D instance must at least do. Otherwise, how can you safely and with confidence substitute a the D in where the B used to be?
But along comes Java, and the MethodNotSupported exception -- a method used by some of Java's core library, including, dismayingly enough, commonly used container classes. It's used so that a derived class can suddenly and at run-time throw it, telling you, "Whoops! Ha ha! Trickled you, I can't in fact really do what B promises! I claim I'm a B, but really, I'm not!"
Now imagine you had a component stereo, and you replaced your tuner with a "better" tuner with all the same jacks as the original. You'd plug it in and expect it to do the same work as the original tuner, just with better reception or fidelity or whatever. Now what if you plugged in the new tuner to the old connections, and suddenly its display read: "Sure, I have a two-plug RCA input, but it's not actually connected to anything, so you can plug in an RCA jack but no sound will come out". That's what having a method that throws MethodNotSupport is like: the jack -- or member function name -- is there, but the implementation is not.
D inherits ("extends") B, it says so right there on the label, but no sound comes out. With Liskov undermined, you don't really have an object oriented language at all. You don't really have true inheritance. What you have is a sham, a sham that can break down on you at run-time because an object is lying to you.
And the upshot is that you don't see enough real object oriented programming by client Java coders. If the core library can get it that wrong, why should clients of that library bother to adhere to a standard?
So you get lots of java code that does RTTI using instanceof and if( p instanceof Foo )
Re:a 'few' rough edges (Score:5, Interesting)
If you use instanceof more than once every, say, 10000 lines of code, I will fight you. That's no lie. It's a sop, and we, the loyal Java programmers of the world, know it's a sop. People who don't know what they're doing can turn it into a crutch. But those of us who DO know what we're doing know that using instanceof should be an automatic hint to rethink the design.
As for MethodNotSupportedException -- yes, it's kind of a hack. But the thing is, perfect designs don't translate to reality very well, and Java, for all its good points, isn't perfect. That exception lets you know when you're breaking an API contract -- though a List may have add() methods, if you want that List to be immutable, is it preferable to throw an exception from a mutator or remove the mutator from the subclass completely? Or should we just take add() out of the List interface? Point is, it's a hack, but it's a lot better than the alternatives. And what it DOES do very well is say, "Look, genius, you're saying two different things about this object. Figure out what you mean and then say it."
I could read stupid C++/D/C/Ruby/whatever code and then blame the language too, you know.
Re:a 'few' rough edges (Score:4, Insightful)
If those are the motivations, we should have an ImmutableList class without an add function, and derive the List with an add function from it (in C++, probably by private inheritance, that is, inheritance of implementation). Only the List class with the (working) add should publically inherit from the interface with an add function.
Problem solved.
"I could read stupid C++/D/C/Ruby/whatever code and then blame the language too, you know."
Sure, sure. Don't be touchy. I code Java too, in fact I'm Sun Certified.
What I'm saying is, you tell me you'd "fight" unnecessary uses of instanceof, and I believe you. I'm just trying to make your fight easier. The point is, if your core libraries don't take liberties, your fellow client coders will be less likely to -- or at least less likely to use the bad example ("but the core library does it, why can't I?") when a good java programmer, like you, points out the problem.
Re:a 'few' rough edges (Score:4, Interesting)
Sure. No argument from me on that. Nothing prevents me from creating my own class that doesn't throw NoSuchMethod.
But the whole point of libraries, you'll agree, is to save the client programmer from having to roll his own, design his own, test his own, code his own -- and then make it interoperate with your code or his code.
And it's his code (not yours, not mine) where the problem sneaks in. (It's always his code, not mine.
Say I'm using Joe's Nifty Library O' Functions. Joe, being a good programmer, doesn't try to roll his own container code -- he knows that no one wants to read up on how his JoeArray or JoeInterator or JoeList are different from the standard, so Joe -- and he's right to do this -- uses standard Java core library classes.
So far so good. But to be good, Joe has to use java.util.List. That's actually an interface, so Joe uses List as his public contract and java.util.ArrayList as the actual implementing class. He uses it as a public member of Joe's Own Nifty Widget with Lots O' Features.
Now you use Joe's library in your code, and you routinely use Widget.getObserverList() like this: myWidget.getObserverList().add( myCallback ) and all is well.
But at some point Joe adds Lenny's Luscious Library to his own code, because it adds all sorts of new functionality to Joe's stuff. But Lenny's library requires that Jow use Lenny's List class. It also implements the java.util.List interface, so Joe -- rather than copy stuff back and forth between lists, just replaces the ArrayList with a LennyList. Joe's code still works, and he releases Joe's Library 2.0.
You upgrade to Joe 2.0, to take advantage of all the new functionality he's added -- in fact, your 2.0 release leverages and relies on lots of the new functionality in Joe's library, and there's no way you could roll your own version in time to meet your client's deadline. And the compiler never complains about your upgrade, because all the interfaces are right, no method calls are made to functions that don't exist.
But at runtime, your code fails. Because Lenny's List has an add function, but never implements beyond throwing an exception. Incredibly enough, Lenny's List is a special proxy listinstanceof too often, they'll just say "see, I told you, object oriented code and using exceptions just ain't reliable."
Of course, the problem is that in using NoSuchMethod, Java isn't actually being object oriented, but after the code throws, try explaining that to the converted C programmers doing java. (Again, not you, not anyone who has read this far -- but we all know and have worked with someone like this, no?)
Now of course, these sort of problems won't arise on small projects. But they'll inevitably arise when your JSP library is calling your Java App server's code which is calling, via RMI, your Distributed Business Object which is calling, via JSQL either an Oracle database (for your domestic operations) or a Sybase database (for the European subsidiary).
I'm curious ... (Score:4, Funny)
Re:I'm curious ... (Score:5, Funny)
Re:I'm curious ... (Score:5, Funny)
Re:I'm curious ... (Score:2, Funny)
Re:I'm curious ... (Score:5, Informative)
Re:How is that 5? (Score:3, Informative)
Re:I'm curious ... (Score:2)
Oh, here's another one: "cocks!" (slightly less boring).
Is threading going to be abstraced out ? (Score:4, Insightful)
Re:Is threading going to be abstraced out ? (Score:2)
There are a lot of good ideas in boost. I use them in my work all the time. But there is also a lot of junk. I would be very selective about adding any of these classes to libstdc++.
Template madness (Score:3, Insightful)
Oh God, please, no!
C++ desperately needs some basic functionality in its standard library: concurrency, GUI, maybe things like sockets. (Alas, by the standards committee's own admission, some of these -- particularly the GUI one -- are unlikely to happen.)
What C++ doesn't need is for its relatively simple but useful standard library to be overwhelmed by every template freak and his brother's pet ideas, which is very much th
Re:Is threading going to be abstraced out ? (Score:3, Informative)
Library Extensions Technical Report 1
or
Library TR1
I knew TR stood for technical report. I have seen both of these refered to when introducing TR1 in articles--primarily in C/C++ Users Journal.
While I am mentioning it. You can download an older draft (January 2005) of TR1 here [open-std.org], and Scott Meyers has updated his page with information mapping items in TR1 to Effective C++ ( which is a must read for all C++ programm
Dogma (Score:3, Interesting)
GLICK
Exactly! And that's what we're looking to do -
shake these people up a bit, get them motivated.
That's the whole point of the campaign. Mass
attendance is at an all-time low in this country.
And it's not like we're losing them to the
Protestants or Baptists - people aren't practicing
at any denomination these days. If we can sell
them some show - let 'em know the Catholic church
has some panache, we can win them back - even get
some new ones. Fill them pews, people - that's the
key. And cross-promoting - like with the cereal
tie-in grabs the little ones as well. Hook 'em
while they're young.
(sits at his desk, lights smoke)
RUFUS
Kind of like the tobacco industry?
GLICK
Oh - if only we had their numbers. But we are
aiming for the same demographic, even though mine
is the soul-saving biz. And if I have to play a
bit of the devil to bring them closer to the Lord,
then I'll wear the cloven hooves and carry the
pitch fork.
-
Today the battle is between Java and C++ and Java wins. Not because it's faster, because it is more convenient.
What C++ could use from Java? Why, an option to have garbage collection for starters. Just an option, not a requirement.
Re:Dogma (Score:2, Insightful)
and you can also code c++.net, which has the option to use the
my personal opinion is c++ should stay exactly like it is. The more libraries the better. if you want some high level language, use c#.net. If you want a headache go with c++.net.
Re:Dogma (Score:5, Funny)
Please download my new folding bicycle! Its lightweight aluminum frame means it's easily portable and rugged too! when not biking, fold it up and carry it under your arm like a briefcase! The perfect form of personal transportation!*
* Note: lightweight bicycle application is powered by a Soviet-era nuclear submarine, a separate download.
A better wheel (Score:5, Insightful)
I've sat through the past 10 years and watched things like Java and D and Objective C come, but meanwhile most serious OS level and game development continues to be in C or C++. Doesn't this demonstrate that new language are merely a distraction to developers who haven't fully exploited the current set?
Re:A better wheel (Score:3, Interesting)
Re:A better wheel (Score:5, Insightful)
Re:A better wheel (Score:5, Informative)
And actually drivers on the NeXT were written in Objective-C ;-)
Anyway, it's all a problem of using the right tool for the right job. Objective-C is excellent (particularly with AppKit + InterfaceBuilder on OSX, or with GNUstep [gnustep.org]+Gorm) for creating graphical applications.
If you need a very optimized code, you can do it in C, or C++... and still keep the rest of the app in Objective-C, as Objective-C is just a superset of C, and the Objective-C++ thingy let you mix C++ code an ObjC code in the same place...
But as they say, early optimisation is the root of all evils :-) which is why most of the time you're much better off with a high-level dynamic language than with a low level or static language. My opinion.
Re:A better wheel (Score:2)
C++0x? (Score:3, Funny)
Perfect opportunity to come up with a decent name but nope, geekiness prevails and the best he can do is: C++0x
Re:C++0x? (Score:3, Informative)
Names (Score:2, Informative)
And I hate PDFs...if it had spiffy charts or images or something, it would be great...but it's just text! Opened it, saved as HTML and it was 78k.
Yeah about that standard library... (Score:5, Interesting)
I would be very easy to do. Just "steal" the API spec's from Java. That's what C# did. Just recode the entire Java API into some C++
Re:Yeah about that standard library... (Score:3, Insightful)
This definition does n
Re:wxWidgets (Score:3, Informative)
This is quite possibly because I've been writing my own abstracted GUI library over the past few years - as both a learning exercise and to produce a useful library, so I admit that I'm biased.
To take an example - for UI/GDI stuff, MFC is just a very thin wrapper over most Win32 objects/calls. It basically takes care of object destruction and has a few (crap) convenience functions, but
C++0x? D! (Score:4, Interesting)
I thought we were staying with C++ because of all the code that's already written in it...
Too little too late? (Score:3, Interesting)
Re:Too little too late? (Score:2)
hiding implementation of templates? how? (Score:2, Interesting)
Tristan
What we need is "Smoothed out" people... (Score:5, Insightful)
Agreed - There are some things that need smoothing, but I for one am tired of dealing with people who lack a fundamental understanding of the *systems* as a whole. Examples of this are the folks coming out with CS degrees who aren't even capable of following a thought, let alone starting an actual career designing and developing software.
For them, a tool like Java offers an entry level that is acceptable given there current capabilities - A tool geared towards THAT user (and a fine one at that).
But C (and C++) can be leveraged by people who know the tool and *use* the tool for what it can do, even with it's high(er, intellectually) cost of entry.
Expected release date (Score:3, Insightful)
Features I want... (Score:5, Interesting)
1. Member function pointers. Implementation dependent and messy syntax that few people even know about. Their use is limited, and they don't support delegates like C#, making them ugly to work with.
2. The "virtual =0" syntax instead of something nice like "abstract" or "interface" is just weird. How can you set a prototype equal to 0? What's wrong with nice words?
3. Operator new and delete were designed by someone on crack. The only way to call a constructor is with placement new, whose syntax looks like: new (var) type(). Placement delete, however, doesn't call the destructor, which must be invoked manually. Furthermore, delete can't take parameters like new. What.
4. There is a "typeid" operator but no "typeof" operator. GCC has an extension for this, but it's not standard C++ I think.
I'm sure there are other language constructs that have annoyed me, and if you don't read my mind and fix them, Bjarne, I will kick you in the pants!
Re:Features I want... (Score:4, Informative)
exactly, and
std::for_each(content.begin(), content.end(),
std::bind1st(std::mem_fun(&PointVisitor::operator
is neither typable nor easy to read AT ALL! plus, it makes my head ache!
Re:Features I want... (Score:4, Interesting)
std::for_each(content.begin(), content.end(),
std::bind1st(std::mem_fun(&PointVisitor::operator
This is one of the reasons i love PHP so much:
foreach($array as $item)
{
}
I never use any for_each crap in C++. I just make sure all my arrays begin at index 0. Sure, it's risky at times, but definitely much more elegant than the half-baked C++ iterators.
Re:Features I want... (Score:2)
Re:Features I want... (Score:5, Interesting)
According to "Effective C++" - Meyers, if you need to know the type of a class, you designed your classes wrong. Take advantage of abstract classes and coercion for this.
Re:Features I want... (Score:3, Interesting)
And the syntax of new and delete is awesome and I like it very much. I don't have time to chat and explain why I mean it is(and suits language well) but it is-trust me on this one. And that delete operator doesn't take arguments, man thats as easy to do the other way as - I mean plain easy.
and yes there is a proposal for typeof
Re:Features I want... (Score:5, Interesting)
The man himself, in "The Design and Evolution of C++" states...
The curious =0 syntax was chosen over the obvious alternative of introducing a keyword "pure" or "abstract" because at the the I saw no chance of getting a new keyword accepted.
Had I suggested "pure", Release 2.0 would have shipped without abstract classes. Given a choice between a nicer syntax and abstract classes, I chose abstract classes. Rather than risking delay and incurring the certain fights over "pure", I used the traditional C and C++ convention of using 0 to represent "not there". The =0 syntax fits with my view that a function body is the initializer for a function and also with the (simplistic, but usually adequate) view of the set of virtual functions being implemented as a vector of function pointers. In fact, =0 is not best implemented by putting a 0 in the vtbl. My implementation places a pointer to a function called __pure_virtual_called in the vtbl; this function can then be defined to give a reasonable run-time error.
Re:Features I want... (Score:5, Informative)
False. Member function pointers are standardized and not implementation dependent. They do have a syntax that is unusual, however. It's unreasonable to expect C++ to support delegates "like C#" considering that C# was designed long after C++.
2. The "virtual =0" syntax instead of something nice like "abstract" or "interface" is just weird. How can you set a prototype equal to 0? What's wrong with nice words?
There is hesitation to introduce keywords, for fear of breaking backwards compatibility. If you program in C++ from dawn to dusk, the =0 notation should be perfectly normal to you, and not a problem in the slightest. They could have made it more descriptive, but it's certainly not a showstopper, and no C++ programmers I know even notice it anymore, as it is just a part of how things are done. Maybe it's a problem for newbies, but you're only a newbie for a short time.
3. Operator new and delete were designed by someone on crack. The only way to call a constructor is with placement new, whose syntax looks like: new (var) type(). Placement delete, however, doesn't call the destructor, which must be invoked manually. Furthermore, delete can't take parameters like new. What. You cannot call constructors, PERIOD. Placement new is not invoking a constructor, it's evaluating a "new expression" using an allocator function that returns the address it is given, and a SIDE EFFECT of that is the invocation of the constructor. It's simply impossible to directly call a constructor in C++.
As for "placement delete", I think you lack understanding. Users are not supposed to invoke placement delete, they are supposed to just invoke the destructor for objects created with placement new. Placement delete is only used to cleanup the memory when an exception causes the constructor to fail. And, as an obviously competant C++ programmer, you should know that if the constructor exits with an exception, the destructor is NOT invoked because the object wasn't constructed and therefore doesn't really exist. Operator new and delete are about MEMORY MANAGEMENT and not object lifetime issues. Constructor and destructors are about that. A "new expression" makes use of operator new and also invokes a constructor. You seem to have confused the "new expression" for operator new.
4. There is a "typeid" operator but no "typeof" operator. GCC has an extension for this, but it's not standard C++ I think.
You're correct, and you may find that we're trying to address this topic in C++0X. If you're interested, see http://www.open-std.org/jtc1/sc22/wg21/docs/papers /2004/n1737.pdf [open-std.org]
Re:Features I want... (Score:5, Informative)
For a full description of just how utterly brain damaged C++ member functions really are check this [codeproject.com]article.
Riddle: What's the size of a method pointer?
1. 4 bytes
2. 8 bytes
3. 12 bytes
4. 16 bytes
5. 20 bytes
6. all of the above
The correct answer is 6. It can be any of these sizes depending on the circumstances. And just imagine that with all of this mess method pointers STILL don't support something as elementary as delegates (bound method pointers) in a dependable and portable way.
The problem with nice words... (Score:3, Insightful)
...is that they're already in use.
Remember that, when the language syntax was designed, the idea was that every conforming C program would also be a conforming "C With Classes" program. Identifiers like "abstract" and "interface" were already in use as user variables, types, functions, etc.
I think you would be pretty pissed off if the next revision of your dawn-to-disk programming language suddenly made "foo" or "i" a reserved keyword. :-)
Time has passed and the two languages no longer fit together
Re:Features I want... (Score:3, Interesting)
Foo f1(3);
Foo *f;
f = new Foo(2);
Maybe a little more thought needs to go into your language suggestions.
Watch out you don't get f'ed (Score:4, Funny)
the language needs to shave of a few rough corners
Yo nee t b carefu whe cuttin corner; i yo cu to fa yo ca reall "f" yoursel ove goo!
--MarkusQ
If you're confused too... (Score:3, Informative)
The '=' have been replaced by '-' signs. (In Acrobat 7 on Windows anyway.) The code makes a heck of a lot more sense once you realize this.
Shave OFF a few rough corners (Score:2, Funny)
*yeah* initializing std::vectors (Score:3, Interesting)
not having a way to initialize a std::vector with some values has always been one minor annoyance for me when using the stl containers!
and about that "expert" thing: it is not by chance that c++ has become an expert-oriented language! there are SO many hidden traps and arcane details to get wrong that one can't just use c++ with intermediate skills and hope not to be punished! even the most simple mistakes can (and will) lead to segmentation faults and memory corruption!
i am not even saying that c++ is an evil language, but it sure as hell isn't newbie-friendly!
Re:*yeah* initializing std::vectors (Score:2)
Just copy them into a back_insert_iterator...
#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
int main() {
typedef std::vector<int> IntVector;
IntVector intVector;
const int values[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
std::copy(values,
values + sizeof(values) / sizeof(int),
std::back_insert_iterator<IntVector>(intVector));
std::copy(intVector.begin(),
Re:*yeah* initializing std::vectors (Score:2)
i am/was quite aware that you COULD somehow get values into a vector. but i resent the necessity of the 4-6 lines of code of yours.
wouldn't it be great to simply write:
std::vector vec = {1,2,3,4};
no matter whether it was pure syntactic sugar or however implemented, but this would elevate std::vectors to a built-in-status that they simply don't have today!
Re:*yeah* initializing std::vectors (Score:2)
If you use the resize() function to explicitly give it a size then the optional second parameter allows you to initialize all the new values to a set value. That's standard, portable, and it works -- even on VC++ 6.0.
Re:*yeah* initializing std::vectors (Score:2)
exactly!
and as BS wrote in TFA, it would be quite nice to initialize vectors with more than 0 members; like so:
std::vector vec = {1,2,3};
this would be especially handy if the values between the braces above are not all the same (in which case one could use vector constructors default value)!
Re:*yeah* initializing std::vectors (Score:3, Informative)
Re:*yeah* initializing std::vectors (Score:3, Interesting)
v += 1, 2, 3, 4, 5, 6, 7, 8, 9
immediatly thinks
v += (1, 2, 3, 4, 5, 6, 7, 8, 9)
i.e. the list of those numbers is added to v. But don't try to type the second line! It will compile quite fine. But it will not do what you want, but rather only append 9 to the vector. However the "intuitiveness" of the method completely relies on that wrong intuition. The true mechanism at
Obligatory (Score:2)
A second wave for C++ (Score:5, Interesting)
The fact is, there's a huge C++ user and code base out there, and if they are going to stick with C++, there's exciting stuff coming.
I feel that C++ is having its second coming, primarily due to developments like the boost library [boost.org] and the Modern C++ Design [moderncppdesign.com] book.
For example, I've been using a combination of boost::function [boost.org] and boost::bind [boost.org] to make powerful, flexible callbacks like nobody's business. Finally, there's a function "pointer" that can work with both freestanding functions, member functions and function objects, and finally there's an easy way to delay calling functions and use closures, respectively. (Also see boost::lambda [boost.org]).
Sure, almost all of this has been possible one way or the other (the flexible callback has been typically implemented via function ptr and void ptr argument, C-style), but it's very refreshing to actually have the code say what you mean: "I want to delay calling this function", or "this callback doesn't give a crap whether the function you're giving it is a member function or not".
Then there are smart pointers [boost.org], which have easier-to-follow, clearer semantics, and can be used in STL containers and such. No more using easy-to-shoot-yourself-in-foot auto_ptr. It's been possible to write large chunks of code that have multiple "new" statements, but have no "delete" statements, all while maintaining exact control over the memory allocation.
Of course there's more... Maybe it's stuff that LISP/Scheme programmers have been using for ages, but the key difference is I can now apply tools in production commercial C++ code, during my everyday work. I no longer sit and say: "oh, crap, I could really use a closure here." I just do it.
A big problem is that the new features require greater understanding of the language and thus better training of the run-of-the-mill C++ developer. Many C++ developers I encounter do not have the sufficient understanding of these tools, and of the language. We should strive to educate our fellow developers,
Syntactic candy. (Score:5, Insightful)
- Some cases where you can type ; where previously {} was necessary, saving as many as two keystrokes.
- The lexer ambiguity where a<b<c>> and a<b<c> > meant entirely different things is fixed, saving as many as one keystroke.
- EVEN MORE "free" constructors which may or may not work quite the way you wanted them to in practice.
- More "fancy cast" operators, which sounds nice until you remember that if there's ever a time you find yourself using the C++ "fancy cast" operators, then there is a damn good chance that it's because you're doing something unwise enough it really would be a better idea to refactor the code to make the "fancy cast" unnecessary.
...in the meantime the fundamental issues with C++ remain not only unresolved, but unaddressed. The template system is still not a generics system, but an ugly cut & paste macro system which can incidentally be used for generics, with some caveats. The class system is still fundamentally brittle and unfriendly to simple things such as upgrading a DLL or determining at runtime if two objects are of the same type. The syntax is still a forest of features whose features interact in ways so crazy and unpredictable it approaches Perl in its chaos; references are still gimped; the distinctions in behavior and use between static and dynamic objects remain awkward and newbie-unfriendly. The features that people obviously desire to have in the language as demonstrated by their tendency to hack them in with third-party libraries (like BOOST) are-- they tell us-- a good thing, and they tell us we should continue to hack them in with libraries (like BOOST). That's nice. You know, that would be a lot easier though if we had a macro system** capable of anything smarter than blind code cut and paste-- or at least a macro system** fundamentally designed to be used for anything at all other than generics.Meanwhile, it appears if I'm reading this right that the most important differences in C++0x will be changes to the standard library. Great. The STL was defined how many years ago, and it's only just in the last few years that compliant implementations have become commonplace? How many decades will it be before the "C++0x" library changes have become common in a cross-platform compatible way?
C++ is an extremely useful language, and making an update to C++ which changes as little as possible so as to follow some kind of "if it aint broken don't fix it" principle is an idea which makes a whole lot of sense. However it seems likely to me from reading this that C++0x will offer so little significant difference from C++ as to make itself simply redundant.
* ("C++0x". Were they specifically trying to come up with a name less convenient than "C#"? Ah well, I guess we can call it "COX" or "cocks" for short.)
** "Template system"
How about a module system? (Score:4, Insightful)
Often there is a separate notation for the modules -- it says what files contain the things, what's exported/imported etc.
That's very useful for encapsulation.
C++'s namespaces are a crappy attempt to get the benefits of a module system -- that's likely where he got the idea from.
Hygienic macros would be a good step too.
Re:How about a module system? (Score:3, Informative)
The using keyword isn't only used in using namespace std;. You can also say things like: using std::vector;. You can also make aliases to namespaces: namespace sp=boost::spirit; Separate things correctly with namespaces, and know how to use using and you'll already have this functionality.
What is C++'s popularity? (Score:3, Interesting)
Strostrup is in denial (Score:4, Insightful)
C++ is the only major language with extensive abstraction but without memory safety. All other major languages are either memory-safe or don't hide the underlying machinery. (Java, C#, VB, Perl, Python, etc. all have automatic memory management. Some use garbage collection; some use reference counts. C is unsafe, but hides nothing.) This fact is responsible for millions of program crashes every day. Most security holes in C++ code come from this problem. Java and C# were invented primarily to eliminate the safety problems of C++. The open source community has generally stayed with C, where at least you can see by examination what's going on. C++ is losing market share to Java.
And Strostrup denies this is a problem.
This has happened before. Last time, it was Wirth. Wirth designed Pascal, Modula, and Modula II, but refused to admit that each had serious problems. He fought external compilation in Pascal. He fought extensions to the language. He even fought compile-time arithmetic. In the end, he took Pascal from a major language to a historical footnote.
Serious systems programming was once done in Pascal, but not in Wirth's version of it. The original Macintosh and Lisa software was written in nonstandard versions of Pascal. And much of the DOS era was built on Turbo Pascal. But proliferating nonstandard versions of Pascal caused another set of problems.
C++ has been in decline for years. "Evans Data [evansdata.com] has found that the percentage of developers using C++ has steadily declined over the last six years--from 76 percent in the spring 1998 to 46 percent in fall 2004." Strostrup also denies that.
The C++ committee has been taken over by template fanatics. Most of the committee's effort revolves around obscure template features that few will use, and which no responsible programming manager would allow on a mission-critical project. There's very little interest in language safety, and a vocal minority that insists language safety is undesirable or impossible.
All is not well in the C++ world. Claming otherwise is irresponsible.
Balance between ease of use and features (Score:3, Insightful)
If any novice is able to pick up Bjarne Stroustrups' The C++ Language and beat him within an inch of his life... but no more, then the book is perfectly balanced between ease of use and richness of features.
As it currently stands, I believe that every second or third novice would easily be able to beat Bjarne to a messy, bloody pulp almost as ugly as the code his language engenders.
It's far too late (Score:4, Insightful)
The largest problem with C++ is its complexity. It is not just too complicated, it is *unmanageably complicated.* Some of the symptoms are:
- The STL has inexplicable omissions. For example, there's no portable way to seed the built-in PRNG in the random_shuffle algorithm, rendering it useless.
- Guruhood isn't good enough. Consider the seemingly simple task of creating a stack that works correctly with exceptions. It's extraordinarily difficult [www.gotw.ca] even for a guru.
- Language features interact in nonintuitive ways, producing a combinatorial explosion. For example, if you overload a function in a class, you don't have to use the scope resolution operator, and if you override a function, you don't have to use it either - but if you do both, you DO have to use the scope resolution operator or else you get a compile error!
Insofar as the new C++ standard adds stuff, instead of simplifying, this will only get worse. Since it's unreasonable to expect a new standard to remove features, the problem is unfixable. The result will be that programmers carve out their separate comfort zones, compiler vendors will not implement all features, and the monolithic C++ language will fragment into a Venn diagram of sublanguages. More so than today.Re:The future of C++... (Score:2, Funny)
Re:The future of C++... (Score:4, Insightful)
Obviously. The same goes for any language. But what do you propose to replace it? The vast majority of "modern" languages are not compiled to machine code. For the moment, C++ is a good balance between the efficiency of C and the user-friendliness of higher-level languages. It fills a niche (resource-gobbling 3D games, operating systems, compatibility with C/C++ libraries, etc) that no other language does.
Re:C++... always the ugly step-kid (Score:2, Funny)
Java is based on Smalltalk!, not on C++
Can not help it, they tell this at the IBM java courses.
Why do C++ if you can do Java/C# (Score:2)
BTW Some people don't see memory allocation as a 'problem'. For many applications you want complete control over memory allocation and you don't want garbage collections and random moments, expecially for applications with a real-time component.
Re:C++... always the ugly step-kid (Score:4, Informative)
Then you had langauges like Smalltalk and Eiffel, elegant languages, simplicity, languages which gave control and power.
i won't dispute that many languages allow much better (data and functional) abstraction than C. but C - in its simplicity as a more readable and slightly more type-safe assembly - had its merits. in C there are no hidden mechanism and you are always right on the bare metal of the machine. so for what it was written for (operating systems, drivers and low-level software) C is actually a veritable and suitable language; far from more abstract languages in its power of abstraction and lacking any kind of real type-safety, BUT it had its applications!
c++ on the other hand takes the principles of C (medium/weak typing, ability to program close to the machine, lack of functional abstraction) and enhanced it by adding hidden mechanisms and arcane problems with values/references/pointers such as object slicing, double freeing, etc.
therefore c++ is neither the bare-metal-language that C was nor is it a real abstraction language like smalltalk, eiffel, lisp, haskell,
on its own, the necessity to think about copy-constructors and assignment-operators for EVERY class one writes is annoying. but together with virtual function calls not working in con/destructors, expressions of form
Class instance();
being interpreted as function declarations and by-default-implicit constructors can bring the aspiring beginner close to the edge sometimes.
Re:C++... always the ugly step-kid (Score:3, Insightful)
Re:standards are nice (Score:3, Funny)
Re:C++ Viability (Score:2)
There is still alot of schools out there with a strong focus in C++. The programs figured if you can learn C/C++, you can learn the rest. The reality is not so true. I have seen plenty of graduated kids really struggling to learn a non-Object oriented language.
Re:C++ Viability (Score:2)
Re:C++ Viability (Score:3, Interesting)
No, I won't forgive you, you pompous fuck. He didnt call himself a scientist, he said he had graduated with a degree in CS. That's what it's called and it has as much right to be called a science as rocket science, which is more obviously engineering than CS.
Re:Why new languages: Why? (Score:3, Interesting)
I agree with you -- but if you read the article, you'll notice that Bjarne's point of view (and for that matter, the prevailing view in the community) is also consistent with yours. Basically, changes in the language are to be as minimal as possible. The changes that he proposes will not make life harder or more confusing. The "new C++" is going to be much the
Why standards are updated (Score:3, Interesting)
There are many reasons to update standards periodically:
1. Most standards bodies (such as ISO) *require* that all standards be updated, or at least
Re:How about... (Score:4, Insightful)
I've been in the profession for over 20 years, and I've seen the same thing happen to certain "standards". Something new and innovative will come along, and within a decade, features will be added that will make it unusable, and foster the demand for "something like X but easier/simpler/faster/cleaner". Most of the feature creep is driven by large corporate interests and the demands of their programming staffs to add features that they claim they can't develop without.
Not many people remember X Window 10R4, but the entire Xlib documentation took up a half-inch thick stack of single-sided pages, and described a basic networked window system that was useful enough to develop distributed systems with. The protocol was easy to implement, straightforward, and clean. But that wasn't good enough for the wonks at Apollo, DEC, HP, Sun, AT&T, and the researchers at MIT. So, once everyone added their "must have" requirements to X Window (we have to have font servers or we can't write good systems!) you ended up with a monstrosity of an Xlib spec that took up a thousand or so pages of documentation, added thousands of new points of failure, and spawned an entire bookshelf from O'Reilly just to try to explain how to use X.
I saw the same thing happen to C++. In the early days it was what it set out to be, a simple, easy to implement extension to C that let you do basic object oriented programming. Sure, it wasn't Smalltalk or Scheme, but it was good enough for 90% of the tasks that really needed simple lightweight objects. But, certain vested software interests demanded that the spec be extended to include things like templates and virtual this and that, all designed to save some corporate programming group some design time, at the expense of creating a spec that required Talmudic scholars to interpret.
I've been on the outside of Java, watching it since it was first described, and I've seen the changes and additions to the language spec over the years. The same thing is happening to Java that I saw happen to X and C++, and I predict that in 10 years or so someone will come out with a language "that does what Java does without all the overhead". I knew Java was doomed to follow the C++/X path when they announced namespace support in the language. Sorry, Javaheads, but that was the tipping point, and you're all on that long slide into obfuscation and bloat that many derided C++ for.
I know many who actually read this post won't believe it, will argue that "Java is different" somehow, but mark my words, Java will bloat into uselessness within 10 years, just like C++ did.