- Boost-users - lists.preview.boost.org

Preprocessor library question
by Tanton Gibbs 19 Dec '02

19 Dec '02

I'm trying to create a template class based on user input. For example: template< int i, int j, int k > class T {}; int main() { int i, j, k; cin >> i >> j >> k; T<i, j, k> t; } Naturally, this is not possible, as i, j, and k must be constants. Therefore, I would like to limit the maximum value of i, j, and k to 100 and create all permutations for T<i,,j,k> at compile time. Basically, something like this: int main() { int i, j, k; cin >> i >> j >> k; if( i == 0 && j == 0 && k == 0 ) { T<0,0,0> t; } else if( i == 0 && j == 0 && k == 1 ) { T<0,0,1> t; } ... else if( i == 100 && j == 100 && k == 100 ) { T<100,100,100> t; } } Naturally, I don't want to type all that in myself, so I was hoping the boost preprocessor library could do it for me. If someone knows of a way to do it, please let me know. Thanks! Tanton [Non-text portions of this message have been removed]

2 1

Matrix-Matrix reference
by Wilken, Marc 18 Dec '02

18 Dec '02

Hello, does ublas support a matrix method like blitz++ .reference() method? (This method allows different matrices to share the same matrix datas.) Marc Wilken This e-mail contains confidential information for the exclusive attention of the intended addressee. Any access of third parties to this e-mail is unauthorised. Any use of this e-mail by unintended recipients such as copying, distribution, disclosure etc. is prohibited and may be unlawful. When addressed to our clients the content of this e-mail is subject to the General Terms and Conditions of GL's Group of Companies applicable at the date of this e-mail. GL's Group of Companies does not warrant and/or guarantee that this message at the moment of receipt is authentic, correct and its communication free of errors, interruption etc.

2 2

Problem with "this" and shared_ptr
by Michael Brinkmann 18 Dec '02

18 Dec '02

Hello, given the following code which uses shared_ptrs, I'm getting a double-free onto an object of type A: ------------------------------------------------------ #include <boost/shared_ptr.hpp> #include <list> #include <iostream> class A { public: A(void){} void makeSomething(void); void makeSomethingOther(void) { std::cout << "A" << std::endl; } }; typedef boost::shared_ptr<A> APtr; class B { public: B(const APtr& a) : mA(a) {} void makeSomething(void) { std::cout << "B" << std::endl; mA->makeSomethingOther(); } private: APtr mA; }; void A::makeSomething(void) { B b(this); // here I want to hand over the "A" shared pointer to "B", but I have only my "this" at hand. std::cout << "A" << std::endl; b.makeSomething(); } int main(void) { APtr a(new A); a->makeSomething(); } ------------------------------------------------------ (please don't ask me about why I'm doing it in that way, the code is stripped down from a much bigger program) I understand that the problem results from the accesss to "this" in the commented line. Is there an elegant way to get the shared_ptr pointing to "this" from "this", which would be the solution to the fault? Or do I have to store a shared_ptr member variable referencing "this" in the class A which is set by a A::method from outside of A to reference it? (not very beautiful) Sorry if this is a FAQ, but I didn't find a solution on news.gmane.org kind regards Michael

4 6

Re: [Boost-Users] Re: Thread library: get thread id
by dick.bridges＠tais.com 18 Dec '02

18 Dec '02

<alternative exemplar> When I implemented the Leader-Follower thread pattern described by Schmidt, et al in Pattern-Oriented Software Architecture, I couldn't figure out a way around comparing the thread id to the current leader in the promote_new_leader function. Probably lack of imagination and/or experience on my part, but having the thread id sure made it easier. </alternative exemplar> "William E. Kempf" To: <Boost-Users(a)yahoogroups.com> <wekempf(a)cox.net cc: > Subject: Re: [Boost-Users] Re: Thread library: get thread id 12/16/2002 01:20 PM Please respond to Boost-Users olivier_debels said: > --- In Boost-Users(a)yahoogroups.com, "William E. Kempf" <wekempf@c...> > wrote: >> >> olivier_debels said: >> > >> > I'm using boost_1_29_0 and need to get the id of the current > thread. >> >> Why? >> > I have several threads which pop messages from the queue. I want to > keep track of what each thread pops (depending on some rules) without > adding an extra parameter (threadId) in the pop-function. I don't follow this. > By this way threads just call the pop-function (they don't know > anything about the internal cooking of the queue). They get a > message, which fulfills the rules (one of the rules is f.e. that no > two threads can handle the same message at the same time). How does a thread id figure into this? What little of this description I understand gives no need for a thread id. William E. Kempf Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

3 4

switching to BGL
by Daniel Varga 18 Dec '02

18 Dec '02

Hi, I'm planning to throw away my own little undirected graph implementation in favor of Boost Graphs. My implementation is based on an STL map< Node,set<Node> > adjecency map. I see that it's very easy to get the same functionality using the BGL adjecency_list. But what I really like about my implementation is that I have const set<Node>& Graph::lookupNeighbours(const Node&) const; This means that in no time I can get a _container_ of the neighbours, and not just a pair of iterators. Of course teoretically they are equivalent. But I want to rewrite as little code as possible, so I would like to wrap my old graph interface around the Boost Graph. (Not hiding its own, better interface, of course. :) ) Should I write a wrapper container class simulating const set<Node>? Or does adjecency_list expose the very same const set<Node>& for me?

1 0

Threads question
by Martin Johnson 18 Dec '02

18 Dec '02

Hi, This has probably been asked before. I cant find doco giving detail. So excuse me if this is old topic. I am involved with GPL project that uses boost::threads. I have a problem understanding implementation and what threadmon.dll is for. I see that the code is attempting to manage tss stuff. How is the tss stuff managed when lib is a static link under win32? Is it correct that if I wish to static link that I need this other threadmon.dll as well. Has it been suggested that structured exceptions can perform the same function on win32 with a finally() handler from within thread_proxy? This is a gurantee of invocation. The cleanup attempt could though win32 doco states cleanup is guranteed, though couldnt a lib global could easily handle main thread cleanup? Regards Martin Johnson

2 1

Thread library: get thread id
by olivier_debels <olivier_debels＠yahoo.com> 17 Dec '02

17 Dec '02

I'm using boost_1_29_0 and need to get the id of the current thread. Is there a way to get the id of the current thread using boost? I don't see how I can access the current thread (Is there some sort of current function?). If I could access the current thread, I could write a getId() function (in a class subclassed from boost::thread). Only problem there is the return type. It seems the id is an int in windows environment, a pthread_t in POSIX and a MPTaskID in MACOS. Those last two seems to be pointers to struct. I guess it is possible to cast all of them to long (using reinterpret casting), but maybe I am overlooking something then. thanks, Olivier.

4 7

Issues on getting the reference of the held value of boost::any
by Seishi Onishi <looper2k＠yahoo.com> 17 Dec '02

17 Dec '02

I'm using a collection of boost::any for the variable container class which has this map member. std::map<std::string, boost::any> m_collection; As you imagine, the container class can keep anything even the container class itself recursively. You know, an boost::any may hold copy expensive object. So I need a method to get the reference of the value held in boost::any not to make the expensive copy. But I found that the current any_cast implementation was not well support the reference. Issue 1: The following code causes compiler error on VC6&7. boost::any dany = double(1.2); double& rd = boost::any_cast<double>(dany); Issue 2: The following code works but one copy constructer called. class Foo foo; boost::any fany( foo ); class Foo& rfoo = boost::any_cast<class Foo>(fany); Actually, I found the way to sneak out of the issues. double& rd = *boost::any_cast<double>(&dany); class Foo& rfoo = *boost::any_cast<class Foo>(&fany); But the problem is these codes won't throw bad_any_cast. And I also wonder this *any_cast usage may not be the way the developer supposed. So I expect that the current any_cast code will be changed to well support the reference access. It can be, template<typename ValueType> const ValueType& any_cast(const any & operand) { const ValueType * result = any_cast<ValueType>(&operand); if(!result) throw bad_any_cast(); return *result; } template<typename ValueType> ValueType& any_cast(any & operand) { ValueType * result = any_cast<ValueType>(&operand); if(!result) throw bad_any_cast(); return *result; } -Seishi

1 0

[Boost-Users][BGL] Permutation of a graph
by Paolo Fosser 17 Dec '02

17 Dec '02

Hi all, I'm using BGL in some graph matching algorithms. Now I have to shuffle a bit one of the graphs I'm comparing. I think it all ends up in considering the nodes in a different order when cycling on them. (BTW am I right?). So my question: is there an elegant way to do this in BGL? The only solution that comes into my mind is to build up a map from the range of vertex descriptors to a permutation of them. TIA, Paolo -- Do you want to live forever? Alex Chiu has invented a device which will give you physical immortality. Click here! http://www.alexchiu.com/affiliates/clickthru.cgi?id=pfosser

2 3

testing if shared_ptr has been assigned
by TEA Hartmann, Steven 16 Dec '02

16 Dec '02

I need some help in testing for the condition of whether a shared_ptr has been assigned. In the following example, the "if( b != NULL ) does not work. How would I do this test? typedef boost::shared_ptr<int> IPtr; int i( 0 ); IPtr a( i ); IPtr b; if( some condition ) b = a; if( b != NULL ) { // How should this really be coded? } Best Regards, Steve [Non-text portions of this message have been removed]

5 4

Borland: Cannot generate template specialization
by Felix E. Klee 16 Dec '02

16 Dec '02

Hi, I'm trying to compile C++ code that uses the boost/numeric/ublas matrix library with the Kylix C++ Compiler (BC++ 5.7 for LINUX). However, I get several error messages, among them: Error E2299 boost_1_29_0/boost/numeric/ublas/matrix.hpp 522: Cannot generate template specialization from 'container_reference<C>' in function matrix<complex<double>,row_major,unbounded_array<complex<double> > >::iterator1::iterator1(matrix<complex<double>,row_major,unbounded_array<complex<double> > > &,complex<double> * const &) Any ideas how to work around this problem? Felix

3 4

Use vc7 toolset for VC7.1?
by Dick Bridges 16 Dec '02

16 Dec '02

Is there a VC7.1-specific toolset or should I continue to use the vc7 toolset? I'd like to avoid the VC6 and VC7.0 workarounds if possible.

2 1

Building problems with regex on a SuSE 8.1 installation
by beat.schaer＠ruag.com 15 Dec '02

15 Dec '02

Hi I tried to compile boost 1.29.0 on a SuSE 8.1 machine and got the following error: gcc-C++-action libs/regex/build/bin/libboost_regex.so/gcc/release/runtime-link-dynamic/shar ed-linkable-true/cregex.o /home/adtsbuilder/boost_1_29_0/boost/regex/detail/regex_match.hpp: In member function `unsigned int boost::RegEx::GrepFiles(bool (*)(const char*, const boost::RegEx&), const char*, bool, unsigned int)': /home/adtsbuilder/boost_1_29_0/boost/regex/detail/regex_match.hpp:1902: Internal compiler error in expand_call, at calls.c:3049 Please submit a full bug report, with preprocessed source if appropriate. See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions. The used compiler is the one delivered with SuSE 8.1. It is a gcc 3.2. Does anybody knows what the problem might be? Regards Beat

4 3

shared_ptr does not call destructor
by Ani Taggu 15 Dec '02

15 Dec '02

Hi: I am using windows 2000 with VC 6.0 and boost 1.28. In my project, I have an array of pointers to objects: class foo { public: ~foo() {} private: std::vector<boost::shared_ptr<MyType> > myArr_; }; I found that the destructor for MyType is never called. Printing the shared_ptr::use_count = 6 at ~foo() above. Any suggestions on what could be happening and how to approach the debugging? Thanks, -Ani

1 0

Test Library: Program Execution Monitor output
by klapshin <klapshin＠yahoo.com> 13 Dec '02

13 Dec '02

Hello, I just plugged program execution monitor in my code and there are certain things I don't really like. First of all is not it odd to see a contradictory messages like: --------------------------- no errors detected **** error return code 1 ********** errors detected; see standard output for details *********** --------------------------- I don't really need this "no errors detected" message. Looking into code I found a way to turn it off -- I have to define an environment variable. I have a way to control this behavior. This is good. Bad news though that the way to control is quite an awkward one. I would like to have some internal control, probably overwritable via environment variable. Another concern is that I have no control on return codes in case of exceptions and runtime errors. For instance in my company all programs have to return 1 in case of failure (and 0 on success). Other return codes are no-no. I am sure there are zillions of different environments with different, often contradictory requirements for error handling. The point I am trying to make is that it is not that difficult to make Monitor more flexible, and it will increase its value tremendously. The ultimate solution would be giving user an opportunity to supply error-handling function which will print out whatever it want to, and return desired return code. Best regards, Kirill Lapshin

2 1

weak_ptr and threads
by Duane Murphy 12 Dec '02

12 Dec '02

The application I am working on uses a number of threads to do work. In some cases pointers from one thread (usually the "main" thread) are passed to a worker thread. The worker thread will use this pointer to handle processing of the results (in various ways). The problem that I am concerned about is lifetime control. Objects in the main thread could be deleted before the worker thread has a chance to use them. This of course would be a "bad thing." I am considering investigating the use of weak_ptr as a potential solution to this problem. The basic idea would be to pass weak_ptr's to the worker thread. The worker thread can then check the validity of the weak_ptr before accessing it. Can weak_ptr be used without using shared_ptr? It seems like they are closely tied. I was hoping to use weak_ptr without forcing the use of shared_ptr. Are there other solutions to this problem, besides the obvious "Dont let it happen." :-) [ Note that we are not yet using boost::threads so this is a more general question about managing inter-thread object lifetimes. ] Thanks for your tips and suggestions, ...Duane

2 1

weak_ptr and threads
by Duane Murphy 12 Dec '02

12 Dec '02

The application I am working on uses a number of threads to do work. In some cases pointers from one thread (usually the "main" thread) are passed to a worker thread. The worker thread will use this pointer to handle processing of the results (in various ways). The problem that I am concerned about is lifetime control. Objects in the main thread could be deleted before the worker thread has a chance to use them. This of course would be a "bad thing." I am considering investigating the use of weak_ptr as a potential solution to this problem. The basic idea would be to pass weak_ptr's to the worker thread. The worker thread can then check the validity of the weak_ptr before accessing it. Can weak_ptr be used without using shared_ptr? It seems like they are closely tied. I was hoping to use weak_ptr without forcing the use of shared_ptr. Are there other solutions to this problem, besides the obvious "Dont let it happen." :-) [ Note that we are not yet using boost::threads so this is a more general question about managing inter-thread object lifetimes. ] Thanks for your tips and suggestions, ...Duane

1 0

uBLAS and fast matrix multiplication
by klapshin <klapshin＠yahoo.com> 12 Dec '02

12 Dec '02

Hello, I am considering switching from in-house matrix implementation to uBLAS. Overall impression from uBLAS is quite good, but it seems that uBLAS does not take advantage of fast matrix multiplication algorithms such as Strassen or Vinograd. Is that correct? If yes, are there plans to implement such algorithms? Best regards, Kirill Lapshin.

3 3

Re: [Boost-Users] testing if shared_ptr has been assigned
by dick.bridges＠tais.com 12 Dec '02

12 Dec '02

I should point out that I went 'back' to get() because I got tired of explaining the 'correct' way [ie, if( b ) ] Darin Adler provided in his answer. |---------+----------------------------------------------------> | | Dick | | | Bridges/CSE/IRV/CONTRACTOR/TOSHIBA-TAIS@T| | | OSHIBA-TAIS | | | | | | 12/12/2002 08:07 AM | | | Please respond to Boost-Users | | | | |---------+----------------------------------------------------> >----------------------------------------------------------------------------------------------| | | | To: Boost-Users(a)yahoogroups.com | | cc: | | Subject: Re: [Boost-Users] testing if shared_ptr has been assigned | >----------------------------------------------------------------------------------------------| >From the docs: <snippet> get T * get() const; // never throws Returns: the stored pointer. Throws: nothing. </snippet> Therefore you can use if( b.get() ) or if( b.get() == NULL ) "TEA Hartmann, Steven" To: boost-users(a)yahoogroups.com <SHartmann(a)aus.t cc: elusa.com> Subject: [Boost-Users] testing if shared_ptr has been assigned 12/11/2002 11:01 AM Please respond to Boost-Users I need some help in testing for the condition of whether a shared_ptr has been assigned. In the following example, the "if( b != NULL ) does not work. How would I do this test? typedef boost::shared_ptr<int> IPtr; int i( 0 ); IPtr a( i ); IPtr b; if( some condition ) b = a; if( b != NULL ) { // How should this really be coded? } Best Regards, Steve [Non-text portions of this message have been removed] Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

1 0

RE: [Boost-Users] Test Library: Program Execution Monitor output
by Tom Matelich 12 Dec '02

12 Dec '02

> I don't really need this "no errors detected" message. Looking into > code I found a way to turn it off -- I have to define an environment > variable. > I have a way to control this behavior. This is good. Bad news though > that the way to control is quite an awkward one. I would like to > have some internal control, probably overwritable via environment > variable. In case you hadn't though of this workaround: if(getenv("VAR") == 0) putenv("VAR=defaultvalue"); Not to say a programmatic method is not worthwhile. ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

2 1

RE: [Boost-Users] testing if shared_ptr has been assigned
by TEA Hartmann, Steven 12 Dec '02

12 Dec '02

Thanks all. That works beautifully. -----Original Message----- From: Tom Matelich [mailto:tmatelich@zetec.com] Sent: Thursday, December 12, 2002 12:25 AM To: 'Boost-Users(a)yahoogroups.com' Subject: RE: [Boost-Users] testing if shared_ptr has been assigned if(b) should do it. shared_ptr has an implicit conversion to bool (sort of). > -----Original Message----- > From: TEA Hartmann, Steven [mailto:SHartmann@aus.telusa.com] > Sent: Wednesday, December 11, 2002 11:02 AM > To: boost-users(a)yahoogroups.com > Subject: [Boost-Users] testing if shared_ptr has been assigned > > > I need some help in testing for the condition of whether a > shared_ptr has > been assigned. In the following example, the "if( b != NULL > ) does not > work. How would I do this test? > > typedef boost::shared_ptr<int> IPtr; > > int i( 0 ); > IPtr a( i ); > IPtr b; > > if( some condition ) > b = a; > > if( b != NULL ) { // How should this really be coded? > } > > > Best Regards, > > Steve > > > [Non-text portions of this message have been removed] > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Get 128 Bit SSL Encryption! > http://us.click.yahoo.com/CBxunD/vN2EAA/xGHJAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. ----------------------------------------------------------------------- Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ [Non-text portions of this message have been removed]

1 0

Re: [Boost-Users] testing if shared_ptr has been assigned
by dick.bridges＠tais.com 12 Dec '02

12 Dec '02

>From the docs: <snippet> get T * get() const; // never throws Returns: the stored pointer. Throws: nothing. </snippet> Therefore you can use if( b.get() ) or if( b.get() == NULL ) "TEA Hartmann, Steven" To: boost-users(a)yahoogroups.com <SHartmann(a)aus.t cc: elusa.com> Subject: [Boost-Users] testing if shared_ptr has been assigned 12/11/2002 11:01 AM Please respond to Boost-Users I need some help in testing for the condition of whether a shared_ptr has been assigned. In the following example, the "if( b != NULL ) does not work. How would I do this test? typedef boost::shared_ptr<int> IPtr; int i( 0 ); IPtr a( i ); IPtr b; if( some condition ) b = a; if( b != NULL ) { // How should this really be coded? } Best Regards, Steve [Non-text portions of this message have been removed] Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

1 0

RE: [Boost-Users] testing if shared_ptr has been assigned
by Tom Matelich 12 Dec '02

12 Dec '02

if(b) should do it. shared_ptr has an implicit conversion to bool (sort of). > -----Original Message----- > From: TEA Hartmann, Steven [mailto:SHartmann@aus.telusa.com] > Sent: Wednesday, December 11, 2002 11:02 AM > To: boost-users(a)yahoogroups.com > Subject: [Boost-Users] testing if shared_ptr has been assigned > > > I need some help in testing for the condition of whether a > shared_ptr has > been assigned. In the following example, the "if( b != NULL > ) does not > work. How would I do this test? > > typedef boost::shared_ptr<int> IPtr; > > int i( 0 ); > IPtr a( i ); > IPtr b; > > if( some condition ) > b = a; > > if( b != NULL ) { // How should this really be coded? > } > > > Best Regards, > > Steve > > > [Non-text portions of this message have been removed] > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Get 128 Bit SSL Encryption! > http://us.click.yahoo.com/CBxunD/vN2EAA/xGHJAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

1 0

Re: Please post Boost.Python questions to Python's c++-sig
by William Trenker <wtrenker＠hotmail.com> 11 Dec '02

11 Dec '02

David, Thanks for this clarification. I was checking out the c++-sig group yesterday and was wondering what that list's relationship was to the official boost list. Now I know why some of my Pythonic questions here were getting blank stares. Cheers, Bill > William, please post Boost.Python questions here: > http://mail.python.org/mailman/listinfo/c++-sig > > Thanks, > -- > David Abrahams

1 0

Python: Wrapping #define's and enum's
by William Trenker <wtrenker＠hotmail.com> 11 Dec '02

11 Dec '02

Many C/C++ libraries contain one or more .h/.hpp files that define various constants used by that library's API. What is the prescribed method for wrapping #defines that are used to represent constants? Also, how do I wrap anonymous enums? For example, I have a project with an Enumerations.h file containing: #define MSG_A 23 #define MSG_B 25 enum {Red, White, Blue = 40 }; What would the boost wrapper code for the above look like? Thanks, Bill

3 2