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Example error for boost::numeric_cast
by Daniel Krügler 14 Nov '05

14 Nov '05

Hello! The example for boost::numeric_cast contains documentation, which clearly is wrong and stumbles the reader. On http://boost.org/libs/numeric/conversion/doc/numeric_cast.html#numeric_cast we have the lines unsigned long l=std::numeric_limits<unsigned long>::max(); // This works, because unsigned integral types cannot cause overflow. unsigned char c=numeric_cast<unsigned char>(l); which contradict the behaviour and the range checking logic presented on http://boost.org/libs/numeric/conversion/doc/converter.html#rchklogic Btw.: Further on the #include directive, namely #include <boost/numeric_cast.hpp> should be corrected to #include <boost/numeric/conversion/cast.hpp> Greetings from Bremen, Daniel Krügler

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intrusive_ptr feature request for constructor
by Bruno Martínez 13 Nov '05

13 Nov '05

Hi. intrusive_ptr's constructor takes an bool to signal whether the refcount should be initially incremented or not. The default is true. I find that the default is different for different types, so I propose to add a hook to specify the policy for each type. At first I thought to do this with traits, but now I think a function is better because this doesn't need to be compile-time and a function overload works fine with ADL. I'm no expert in this, so maybe I'm mistaken somewhere. What I propose is to add: namespace boost { template <class T> bool intrusive_ptr_add_ref_at_construction(T*) { return true; } template<class T> class intrusive_ptr { intrusive_ptr(T * p, bool add_ref = intrusive_ptr_add_ref_at_construction((T*)0)): p_(p) { if(p_ != 0 && add_ref) intrusive_ptr_add_ref(p_); } ... } } then I can do bool intrusive_ptr_add_ref_at_construction(MyType*) { return false; } What do you think of this feature? Regards, Bruno

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Documentation question. Format and lexical_cast
by Drumheller, Michael 13 Nov '05

13 Nov '05

There seems to be some considerable overlaps in functionality between boost::lexical_cast and boost::format, yet, as far as I can tell, the documentation pages for each does not mention the other. Is this intentional, or would anyone agree that a doc fix would be in order? (Needless to say, if so, I would be happy to help with it.) Thanks, Michael D.

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Boost.Serialization vs STL containers of 'double'
by Adam M 12 Nov '05

12 Nov '05

Hi, I am using Boost.Serialization to serialize a std::map<std::string, double>. It works fine, except that the precision on the double is not enough for my application. Is it possible to manipulate the precision used when serializing/deserializing double's within an STL container? I tried using setprecision(), but it doesn't understand the "&" stream operator that the Serialization library uses. Thanks, Adam

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MultiArrays of Std::Lists: why const iterators?
by Joshua Schpok 12 Nov '05

12 Nov '05

I want to make a 3D array of std::lists: boost::multi_array<std::list<CSomething>,3> listbin; Then I'd like to actually use those lists: /// Walk through list at x,y,z for(std::list<CSomething>::iterator iter = listbin[x][y][z].begin(); reti != iter[x][y][z].end(); iter++) { iter->m_foo += 42; } But multi_array is giving me back *const* list iterators, producing the error: error: conversion from `std::_List_const_iterator<CSomething>' to non-scalar type `std::_List_iterator<CSomething>' requested Why is this so? I can trick the compiler by doing a cast like: std::list<CSomething>::iterator iter = ((std::list<CSomething>)listbin[x][y][z]).begin(); but this seems to poop out at runtime. Is there a proper way to do this? Joshua Schpok

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[bind]How to bind to a template class member function?
by Wang Yun 12 Nov '05

12 Nov '05

Hi, I tried to bind to a class member function template, but can't pass compile, what's the correct syntax or this is impossible? class A { public: void test() { function<void()> func; func = boost::bind( &A::ttt<int>, this ); } template<typename T> T ttt() { return 1; } }; int _tmain(int argc, _TCHAR* argv[]) { return 0; } Thanks, Wang Yun

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[serialization] Incorrect assertion in basic_binary_oprimitive?
by Austin Bingham 12 Nov '05

12 Nov '05

I've run into a situation where I'm triggering an assertion at basic_binary_oprimitive::save_binary(). This is on basic_binary_oprimitive.hpp, line 115 in version 1.32. This assertion seems to be claiming that an output stream will always be in a "good" state after a call to write(). On it's face, I think there's no way to safely make that claim, especially about a stream whose type is a template parameter. In fact, as I understand it, good()'s whole purpose is to let you know that the stream is busted. Am I misunderstanding something, or should that assert be changed to an exception? I'm trying to get an example program that demonstrates this problem. Currently, the code that exercises it is big and hairy, and I haven't pared down the precise conditions that cause it to happen. I can provide a stack trace, however, which may be of some use. -- Austin Bingham "If I were creating the world I wouldn't mess about with butterflies and daffodils. I would have started with lasers, eight o'clock, Day One!" Evil

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When FSM library is released
by Oliver.Kowalke＠infineon.com 11 Nov '05

11 Nov '05

Hello, could you tell me please when the next release of boost with fsm (finite state machine) library will be released? thx, Oliver

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Namespaces for Intrusive Serialization?
by Merrill Cornish 11 Nov '05

11 Nov '05

In the Serialization tutorial, and example is given of the "intrusive" method that looks like this: private: friend class boost::serialization::access; template<class Archive> void serialize(Archive& ar, const unsigned int version) { ar& var1; ar& var2; ar& var3; } There is full namespace qualification on "access" but nothing on "serialize()". It appears that serialize() would be in whatever the prevailing application namespace is (which might not be std). Later in the tutorial there is an example of the "non-intrusive" method that looks like this" namespace boost { namespace serialization { template<class Archive> void serialize(Archive& ar, const unsigned int version) { ar& var1; ar& var2; ar& var3; } }//serialization }//boost which implies that serialize() *DOES* need to be namespace qualified. So, what's really needed? Merrill

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Deploying Boost App: Best Practices?
by Merrill Cornish 11 Nov '05

11 Nov '05

I am building an open source C++ application using various Boost libraries. I am using the libraries as-is without any tweaks, additions, or wrappers to the source or headers. What is the accepted way (if there is one) of deploying a Boost application when the application includes the source under an open source license? Should I distribute only *my* source along with instructions to users who want to compile it to download the Boost libraries? Or, should I include a boost/ subdirectory in my source tree with the Boost headers and libraries my app uses? Merrill

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