May 2006 - Boost-users - lists.boost.org

boost::bind, boost::function & placeholders flexibility
by jbd 13 May '06

13 May '06

Hello everybody, First of all, i'm a beginner trying to understand the use of the boost::bind library. Here is my problem : I'd like to know if there is a way to omit placeholders when calling boost::bind and let the compiler deduce their number. I understand that this is contrary to the flexibility offers by the placeholder, but i need to do something like that. void bar() {} void bar2(int) {} // Compile and works well boost::function < void ()> f1( boost::bind(&bar) ) ; boost::function < void (int) > f2( boost::bind(&bar2,_1) ) ; // i'd like to write this, but it doesn't compile // without the placeholders boost::function < void (int) > f2( boost::bind(&bar2) ) ; // i can write a small helper function mybind to achieve my goal // this compile and works well mybind(bar2) ; with template <typename Ret, typename Arg1, typename Arg2> void mybind(Ret (*Func)(Arg1, Arg2)) { boost::function<Ret (Arg1, Arg2)> f(Func) ; } I hope you understand what i've try to show. Maybe i missed something in the documentation. Thank you for reading ! Here is the working .cpp file i use to test things. =============================== #include <iostream> #include <stdexcept> #include <boost/bind.hpp> #include <boost/function.hpp> template <typename Ret, typename Arg1, typename Arg2> void mybind(Ret (*Func)(Arg1)) { boost::function<Ret (Arg1)> f(Func) ; } void bar() { std::cout << "bar()\n" ; } void bar2(int a) { std::cout << "bar2(int)\n" ; } int main (int argc, char* argv[]) { try { // Compile and works well { boost::function < void ()> f1( boost::bind(&bar) ) ; boost::function < void (int) > f2( boost::bind(&bar2,_1) ) ; } /* // i'd like to write this, but it doesn't compile { // without the placeholders boost::function < void (int) > f2( boost::bind(&bar2) ) ; f2(5) ; } */ // i can write a small helper function mybind to achieve my goal // this compile and works well /* template <typename Ret, typename Arg1, typename Arg2> void mybind(Ret (*Func)(Arg1, Arg2)) { boost::function<Ret (Arg1, Arg2)> f(Func) ; } */ { mybind(bar2) ; } } catch(std::exception& e) { std::cout << e.what() << '\n' ; return -1 ; } catch(...) { std::cout << "Non standard exception\n" ; return -1 ; } } ========================================

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Linking problems with boost::test in multiple modules.
by steve ahlgren 12 May '06

12 May '06

Hello : I am using boost::test to provide testing in multiple modules (dlls on win32). A single exe is used to call each of the test facilities in each module. In theory the above sounds ideal, especially as each individual unit test within a module is registered via an abstract factory. In practice, however, I am unable to link the individual modules properly as each one seems to require the function init_unit_test_suite() to be defined. This is mentioned in the FAQ but I have not yet found documentation or examples documenting boost::test spanning multiple modules. I would think that one instance of init_unit_test_suite() would be necessary within the controlling exe, and that each module (dll) would link statically against the boost::test library. Linking against this library, however, causes the problems described above. If anyone has suggestions or an example I would be grateful. Many thanks; sga

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Re: [Boost-users] [BULK] Re: MPL/Fusion
by Sohail Somani 12 May '06

12 May '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Arkadiy Vertleyb > There could be different opinions on this subject, but I > think the basic > rule of thumb should be: no template metaprogramming in the > non-library > code. Of course, most C++ programmers are wearing two hats: a library > (reusable code) writer and the user of this reusable code. > The key is to > distinguish which hat you are wearing at any particular moment :-) I find that increasingly it's the library, so maybe I'm on the right path. Thank you for your input! Sohail

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Re: [Boost-users] MPL/Fusion
by Sohail Somani 12 May '06

12 May '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > Sohail Somani > Sent: Thursday, May 11, 2006 9:18 AM > To: boost-users(a)lists.boost.org > Subject: [Boost-users] MPL/Fusion > > Hi, > > I am quite interested in MPL/Fusion. I have made my own toy projects > using template metaprogramming to make decisions at compile time. I am > interested in learning what types of software boost users create with > it. > > Would anyone care to share? I think I should clarify: I meant non-library uses (like the maze app, I'll take a look thanks!). Like a programmer who also uses shared_ptr. Although I can think of a few instances where I would use it for work, I just want to tell myself that I am making things complicated and want your help to make sure I'm making better code. Sorry if that's even MORE confusing :) Sohail

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[date_time] Error in time_period documentation
by Ward, Arthur (Mission Systems) 12 May '06

12 May '06

To the documentation maintainers for date_time: I just noticed an error in the documentation for boost::posix_time::time_period in 1.33.1. According to the Posix Time documentation, time_period has the method "time_period shift(days)". As far as I can see, it should be "void shift(days)" and listed as a mutator.

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[Boost.program_options] Boolean option
by Kobi Cohen-Arazi 12 May '06

12 May '06

Hi, boost-1.32.0-6 I've tried to find in the program_options docs how to specify a regular boolean switch. If I use <bool>, it still demand putting something That's what I would like to have ./prog -t and not ./prog -t1 Right now, when using <bool> it will throw an exception if I'm not using the -t1 notation. Am I missing here something? Thanks, Kobi.

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[Boost.dynamic_bitset] Help on extending dynamic_bitset
by Kobi Cohen-Arazi 12 May '06

12 May '06

Hi, boost-1.32.0-6 I would like to hear your suggestions regarding the ways to extend dynamic_bitset. Let's say that I have a different way to search for the next bit in the set. It is specific to my CPU arch. How can I extend find_first/find_next ? Since there is no way to retrieve the internal vector<>, It seems very hard to do so. Nothing is protected so Inheritance is out of the question, and there is not a single accessor that expose that vector<> (its best not to do so, but I'm just counting the options here). Am I missing another way of extending it? Thanks, Kobi.

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[date_time] build error
by Leif Gruenwoldt 12 May '06

12 May '06

I have implemented a class ( lets call it LC2DateTime ) that uses boost date time in it's implementation. I also have a small test for this class and it builds nicely and runs properly. However when I include LC2DateTime.h in my larger project I get this odd build error that points me to /usr/include/boost/algorithm/string/detail/finder.hpp as the source of the error. ------------------ /usr/include/boost/algorithm/string/detail/finder.hpp: In member function 'boost::iterator_range<Iterator> boost::algorithm::detail::last_finderF<SearchIteratorT, PredicateT>::findit(ForwardIteratorT, ForwardIteratorT, std::forward_iterator_tag) const': /usr/include/boost/algorithm/string/detail/finder.hpp:150: error: expected unqualified-id before numeric constant /usr/include/boost/algorithm/string/detail/util.hpp: At global scope: /usr/include/boost/algorithm/string/detail/util.hpp:71: error: expected ',' or '...' before numeric constant /usr/include/boost/algorithm/string/detail/util.hpp: In function 'OutputIteratorT boost::algorithm::detail::bounded_copy(InputIteratorT, InputIteratorT)': /usr/include/boost/algorithm/string/detail/util.hpp:76: error: 'DestFirst' was not declared in this scope /usr/include/boost/algorithm/string/detail/util.hpp:77: error: 'DestLast' was not declared in this scope ---------------------- This bug has been bothering me for a while and I actually got my project to build again juggling the placement of of the '#include "LC2DateTime.h" above the other includes in my project. However this problem has reared it's head again and this time no amount of juggling of includes is getting me out of this. Any thoughts? Is this a problem with the boost libraries or my code? -- Leif Gruenwoldt Simulation Software Developer DLCSPM 4-4-3 (c) Building A31 CFB Kingston

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Mailing lists to go down Saturday
by David Abrahams 12 May '06

12 May '06

-- Dave Abrahams Boost Consulting www.boost-consulting.com

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a problem on boost::asio
by 李慧霸 12 May '06

12 May '06

I'm trying asio on WindowsXPSP2 + VS2003, and I found that there are always some connections established from 127.0.0.1:xxxx to 127.0.0.1:yyyy, is it a bug?

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