- Boost-users - lists.boost.org

how to expose the func like "print( char * str, ... )" ?
by iceryeah 10 Feb '04

10 Feb '04

hello, problem 1: i can expose the function like void a( void ) def( "a", a ); but there is anthor function like this: void DebugMessage( char *msg,... ); i don't know how to expose this function. problem 2: module test int num = 0; void set( int a ) { num = a; } then i expose set func , and do this in script: import test test.set( 10 ) and then in host app, i check the var num, it is not 10,why? thanks very much.

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Spirit: a skip parser that counts newlines?
by Steve Folly 10 Feb '04

10 Feb '04

Hi, Before I launch into it, does anybody have an example of a parser that can count newlines. I would have thought this would be quite common, so I'm surprised to see it's not standard within Spirit? (Or maybe I didn't look hard enough?) I'm writing a parser which will parse multi-line files. I'd like to report an error along with a line number. I realise the error can't be detailed - e.g. what the parser expected, rather, just 'an error' - which why I'd like the line number to at least give the user a fighting chance. I assume the parser simply stops at the point where parsing failed, and thus I'd know the line number? I'm guessing I'd have to supply this as a custom skip parser to the parse method? Thanks for any clues. -- Regards, Steve.

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RE: [Boost-users] configuring boost on MS Visual Studio 6 where the installation drive isn't C:
by Ben Hutchings 10 Feb '04

10 Feb '04

Someone using the wrong account to write email <Administrator(a)sbcltd.com> wrote: > Wayne, > > There might still be conflicts if the compiler can't place everything > into it's proper namespace. In addition, some sdk's force > everything into std namespace Really? That would be truly evil. > or into the global namespace. If you use "using namespace boost;", > you're basically doing the same thing. > > There are a couple of options that could be used separately. <snip> > 2. The second is wrap the offending sdk in it's own namespace. Here > is what I have come up with. I have three files here. c.h is the > original function. b.h wraps it in it's own namespace, and main.cpp > can only use it with the new namespace. Simple example, but hopefully > it illustrates what I'm trying to get across. <snip> That's all very well for inline code, but how about external code that's linked in later, that has been compiled without using the namespace? By the way, possessive "its" has no apostrophe.

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[BGL] Removing vertices and internal properties
by Frédéric Mayot 10 Feb '04

10 Feb '04

Hi, I have a graph in the form of an adjacency_list with an internal property. I'm using vecS for both vertices and edges (and I don't want to use listS). When I remove a vertex with remove_vertex(), it seems that my property map is invalidated. Can I remove the property (from the map) which corresponds to the deleted vertex ? Is there any solution ? Thanks. Fred

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Dynamic Multi Array Library
by RGProlog＠aol.com 10 Feb '04

10 Feb '04

Is anyone interested in dynamic_multi_array template library that offers user intuitive convenience of use as well as capacity to hone in upon any specific subset of a multi-dimensional array? As an example of usage, a dynamic_multi_array object can be constructed and then resized and then reshaped like this: size_t arrayShape = { 3, 7, 15}; dynamic_multi_array<double, 3> A(arrayShape); boost::array<size_t, 3> anotherArrayShape = {{ 5, 4, 22}}; A.resize(anotherArrayShape); boost::array<size_t, 5> yetAnotherArrayShape = {{ 440, 1, 1, 0, 0}} ; A.reshape(yetAnotherArrayShape); size_t stillAnotherArrayShape[4] = { 22, 10, 2, 11}; A.reshape(stillAnotherArrayShape); The library’s design owes a lot to Andrei Alexandrescu’s ideas. It is based on the data_table helper class template defined as follows: template<typename X> class data_table { … protected: std::vector<X> data_table_ ;}; template<> <value_type> class data_table { … protected: value_type* data_table_ ;}; Then, a sequence of the table class instantiation types is recursively defined and then given a name that is shared in different dimensional contexts as follows: typedef data_table<value_type> data_table_01; ……………………………………………. typedef data_table< data_table_49 > data_table_50 ; class Int2Type<int> { typedef data_table_01 data_table; } …………………………………………… class Int2Type<> <50> { typedef data_table_50 data_table; } Being a recursive template class, the data_table is implemented in a concise code that is mostly about stating a few recursive rules and implementing some access operators and is totally dimension independent. This is the central feature of the design since the user level wrapper class template by virtue of exporting a dimension appropriate data_table instantiation that uses its shared name template <T, size_t i, Allocator> class dynamic_multi_array { ………………………………………. typedef …. class Int2Type <i>::data_table; } is also implemented in a way that hides all the implementation details, is concise and dimension independent, thus providing user with a great deal of flexibility, syntax safety, and, in case of a new user, a flat learning curve. This is a std::vector based design. The dynamic_multi_array template class, the library’s main component, extends, where appropriate, std::vector capacities, replicates its exception safety guarantees and has std::vector as its back end storage device. The library’s code, documentation that includes a short tutorial and a few key tests and will be posted in Dynamic Multi Array Folder on boost Files once the issue of available space will be resolved.

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(no subject)
by RGProlog＠aol.com 10 Feb '04

10 Feb '04

Is anyone interested in dynamic_multi_array template library that offers user intuitive convenience of use as well as capacity to hone in upon any specific subset of a multi-dimensional array? As an example of usage, a dynamic_multi_array object can be constructed and then resized and then reshaped like this: size_t arrayShape = { 3, 7, 15}; dynamic_multi_array<double, 3> A(arrayShape); boost::array<size_t, 3> anotherArrayShape = {{ 5, 4, 22}}; A.resize(anotherArrayShape); boost::array<size_t, 5> yetAnotherArrayShape = {{ 440, 1, 1, 0, 0}} ; A.reshape(yetAnotherArrayShape); size_t stillAnotherArrayShape[4] = { 22, 10, 2, 11}; A.reshape(stillAnotherArrayShape); The library’s design owes a lot to Andrei Alexandrescu’s ideas. It is based on the data_table helper class template defined as follows: template<typename X> class data_table { … protected: std::vector<X> data_table_ ;}; template<> <value_type> class data_table { … protected: value_type* data_table_ ;}; Then, a sequence of the table class instantiation types is recursively defined and then given a name that is shared in different dimensional contexts as follows: typedef data_table<value_type> data_table_01; ……………………………………………. typedef data_table< data_table_49 > data_table_50 ; class Int2Type<int> { typedef data_table_01 data_table; } …………………………………………… class Int2Type<> <50> { typedef data_table_50 data_table; } Being a recursive template class, the data_table is implemented in a concise code that is mostly about stating a few recursive rules and implementing some access operators and is totally dimension independent. This is the central feature of the design since the user level wrapper class template by virtue of exporting a dimension appropriate data_table instantiation that uses its shared name template <T, size_t i, Allocator> class dynamic_multi_array { ………………………………………. typedef …. class Int2Type <i>::data_table; } is also implemented in a way that hides all the implementation details, is concise and dimension independent, thus providing user with a great deal of flexibility, syntax safety, and, in case of a new user, a flat learning curve. This is a std::vector based design. The dynamic_multi_array template class, the library’s main component, extends, where appropriate, std::vector capacities, replicates its exception safety guarantees and has std::vector as its back end storage device. The library’s code, documentation that includes a short tutorial and a few key tests and will be posted in Dynamic Multi Array Folder on boost Files once the issue of available space will be resolved. P.S. The space issue is that I freed the space I previously occupied on boost Files and still cannot post the message. Need help here.

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RE: [Boost-users] configuring boost on MS Visual Studio 6 where the installation drive isn't C:
by Dernoncourt, Wayne CTR NAVAIR 3184, ,10 09 Feb '04

09 Feb '04

Thanks much. I think the folks here have sent a message (I leave here a little after 1:30 on Friday and discussion sometimes takes a while) to the other SDK developers asking if they could put their SDK in a namespace and do this the "right" way instead of this round-about method. But yes this could work as well. Thanks much. -----Original Message----- From: boost-users-bounces(a)lists.boost.org [mailto:boost-users-bounces@lists.boost.org]On Behalf Of Administrator Sent: Friday, February 06, 2004 12:57 To: 'Boost Users mailing list' Subject: RE: [Boost-users] configuring boost on MS Visual Studio 6 where the installation drive isn't C: Wayne, There might still be conflicts if the compiler can't place everything into it's proper namespace. In addition, some sdk's force everything into std namespace or into the global namespace. If you use "using namespace boost;", you're basically doing the same thing. There are a couple of options that could be used separately. 1. One is to not use "using namespace". Preface everything used from there with boost:: or std::. More typing, less pain, less chance for conflict. 2. The second is wrap the offending sdk in it's own namespace. Here is what I have come up with. I have three files here. c.h is the original function. b.h wraps it in it's own namespace, and main.cpp can only use it with the new namespace. Simple example, but hopefully it illustrates what I'm trying to get across. -------------------------------------------------- c.h ------------------------------------------------- #ifndef _C_H #define _C_H inline int garbage_method() { return 0; } #endif // -------------------------------------------------- b.h -------------------------------------------------- #ifndef _B_H #define _B_H namespace garbage_namespace { #include "c.h" } #endif // -------------------------------------------------- main.cpp -------------------------------------------------- #include "b.h" int main() { return garbage_namespace::garbage_method(); }

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suspend/cancel thread
by janardhan.guptha＠efi.com 09 Feb '04

09 Feb '04

Hi, i working on an application using boost::thread. The application cretaes a thread, then put in wait state. Based on the user input i want the thread eitjer to move it to run state or cancel the thread. As i am newbie to boost thread, i couldn't find any documentation or working example that satisfies my requiremnt. So someone can help me out?? Rgds, Janardhan

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std::map problem.
by Joshua Little 09 Feb '04

09 Feb '04

I'm working on making a factory class but have run into a problem. I think I'm trying to get the shared pointer out the wrong way. std::map<std::string, boost::shared_ptr<Logger> > LoggerFactory::loggers; boost::shared_ptr<Logger> LoggerFactory::getInstance(std::string& logger) { boost::shared_ptr<Logger> TheLogger; LoggerMap::iterator i = loggers.find(logger); if (!(*i).second.get()) { TheLogger.reset(new Logger()); loggers[logger] = TheLogger; } else { TheLogger = (*i).second; } return TheLogger; } I thought that the TheLogger = (*i).second line was the correct way to get any logger within the map but when I run it I get this segfault: Program received signal SIGSEGV, Segmentation fault. LoggerFactory::getInstance(std::string&) (logger=@0x22ff58) at e:/boost-1.30.2/boost/detail/shared_count.hpp:123 123 if(use_count_ == 0 && weak_count_ != 0) boost::throw_exception(boost::bad_weak_ptr()); if I comment out the 'TheLogger = (*i).second;' line everything seems to fine. Any ideas? Joshua.

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Help with shared_ptrs please
by Steve Folly 09 Feb '04

09 Feb '04

Hi, I'd like some help trying to crack a problem I've got. Now, I am using shared pointers at the moment, and that might be part of my problem, or it might not, but I'll describe the situation and you can tell to go elsewhere if you like! :) Part of my application involves scripting - allowing the user to write file based scripts to execute within the context of an application. I've designed it so it also gives the ability for the application writer to create some 'scripts' by creating classes directly in the C++ code. The script has the ability to run in the main thread of the app, but some statements could potentially block, so each statement is run from a 'timer' event which gets scheduled immediately. Those that block wait for an event and continue on that event. This part is working well. The statements are classes constructed in a hierarchical manner with things like a block class (a statement itself) which has a list of statements in it, an if statement class - which has an expression evaluator, a statement for the 'then' part, and an optional statement for the 'else' part. You get the idea? After looking at boost::lambda I thought it would be nice if I could construct my script similar to how lambda does these sorts of control statements - the if_, switch_, for_ constructs. The idea I have is like: expression exp = ... If_statement s1 = if_( expr)->then_( s2 )->else_( s3 ); while_statement ws = while_( expr ).do_( s1 ); One of the things I decided early on was to use shared_ptrs. The while_ and if_ constructs are functions returning a shared pointer to the real if statement object. Now my problem: given the example above. The do_ method of a while_statement takes a shared pointer to a statement so I don't have to worry about deallocation. Constructing the if_ statement on it's own is no problem, but if I was to construct one directly within the do_ part of the while statement it wont compile: while_( expr ).do_( if_(expr)->then_(s2)->else_(s3) ); The problem is to be able to chain then_ and else_ together, I have to return a plain pointer because the if_ statement itself doesn't know about it's shared pointer. So now, the compiler complains that can't implicitly convert a plain if_statement pointer into a shared pointer. And even if it could, I don't have the original shared pointer to hand. Now, I hope you're all still listening at the back! :) My first thought was to somehow get the object to look after the shared pointer, but surely if the object has a reference to itself, the ref count of the shared pointer could never reach zero? As I said right at the beginning, I think is a problem I have with shared pointers, whether it be a misunderstanding about them or maybe I'm using them the wrong way? I could always go for scrapping the shared pointers all together, and make the classes responsible for their own (de)allocation, but I was rather hoping to avoid that. Any tips and suggestions on ways forward will be much appreciated. (Even if to say - "ha! it'll never work", or "try a another newsgroup"! :) TIA. -- Regards, Steve.

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