- Boost-users - lists.boost.org

Off Topic: Boost Book
by Etienne Philip Pretorius 21 Jul '09

21 Jul '09

Hello List, Any thoughts about this book: http://www.amazon.com/Beyond-Standard-Library-Introduction-Boost/dp/0321133… Also, any other recommendations (for boost) will be appreciated. Thank you, Etienne

6 6

[log] More than one module but static linking?
by Boris Schaeling 21 Jul '09

21 Jul '09

Andrey, the documentation of your very useful logging library says: "If your application consists of more than one module (e.g. an exe and one or several dll's) the library must be built as a shared object." As it turns out I want to use your library in such an application. However there is only one module writing to the log file. Do I still need to use the shared library? Or can I link statically if for example I don't use certain parts of the library? As far as I see there is no more information in the documentation why linking dynamically is forbidden? Boris

1 0

boost::mpl::inherit from a typelist?
by Zachary Turner 21 Jul '09

21 Jul '09

When I use typedef boost::mpl::inherit<boost::mpl::list<udt1, udt2, udt3> >::type derived_class; (at least in MSVC) then it inherits directly from boost::mpl::list, instead of inheriting from the individual members of the list. Is there a way to make it inherit from each type in the list instead? inherit_linearly appears to accept anything modelling the ForwardSequence concept as its template argument, so it seems like inherit should do the same unless I'm just missing something.

2 1

[lambda] instantiation in bind
by Igor R 21 Jul '09

21 Jul '09

In VC9.0 the following code gives the error message: 1>...\boost\tuple\detail\tuple_basic.hpp(419) : error C2259: 'Base' : cannot instantiate abstract class If the Base is not abstract, the code compiles and works as expected. Unfortunately, I'm unable to realise why it tries to instantiate the Base, and how to overcome this issue, so any enlightenment would be greatly appreciated! class Base { public: virtual void close() = 0; }; class Derived : public Base { public: void close() {} }; #include <boost/shared_ptr.hpp> typedef boost::shared_ptr<Base> BasePtr; typedef boost::shared_ptr<BasePtr> BasePtrPtr; #include <boost/lambda/lambda.hpp> #include <boost/lambda/bind.hpp> namespace bl = boost::lambda; BasePtrPtr makeHolder(Base *base) { return BasePtrPtr(new BasePtr(base), bl::bind(&Base::close, **bl::_1)); } int main() { Base *b = new Derived(); makeHolder(b); return 0; }

3 4

[boost][format] How does one determine the number of format arguments?
by Neil Groves 21 Jul '09

21 Jul '09

Dear all, Please accept my apologies if this ends up being a double post. I am having trouble with posting to the boost mailing lists. I have the need to obtain the number of 'arguments' (the %1% thingies!) in a boost::format. Is this functionality supported in a manner that I have failed to find in the documentation? If it is not supported, would it be a worthwhile addition since it seems easy to add assuming the num_args_ member variable is the information I require and that validation code of boost::format instances is commonly very useful. I have rarely executed error code that uses boost::format that is difficult to test, but by adding a StringTable that loads at module startup and wraps the boost format, I can provide compile-time validation of much of the formatting code, and runtime validation of the format strings at module startup. This would make it much easier to test. Thank you for your time and consideration. Regards, Neil Groves

3 2

[Math Toolkit] Gamma Distribution
by Christian Henning 21 Jul '09

21 Jul '09

Hi there, the documention of the gamma distribution talks about two different forms. How can can generate the second one with shape=1 and scale=1? I know how to get the first form: boost::math::gamma_distribution<> dist( 1, 1 ); I don't see how to get the second one? Thanks, Christian

5 13

Spirit 1.39 compilation times
by Avi Bahra 21 Jul '09

21 Jul '09

>First, you should use Boost Trunk, it compiles quite noticeably faster. >Second, look in the Spirit examples directly with Boost Trunk, in the >QI subdirectory, the mini_c directory has an example of just that. I cant use use boost trunk, in order to get faster compiles, since I have to use boost1.38/1.39. Also it looks like the grammar construction in the examples is different. I looked for a similar example in boost 1.39 since we use closures but none exists. Surely anyone who is using spirit and building on multiple platforms must be be affected with this bug ? Best regards. Avi ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// Message: 4 Date: Mon, 20 Jul 2009 10:37:57 +0100 From: Avi Bahra <avibahra(a)googlemail.com> Subject: [Boost-users] Spirit 1.39 compilation times To: boost-users(a)lists.boost.org Message-ID: <af1b101f0907200237ofdf91bbk98be95d0ab817208(a)mail.gmail.com> Content-Type: text/plain; charset="iso-8859-1" I am using boost spirit 1.39. On gcc the compilation times are acceptable. However on AIX with v10.1 compiler, it fails to even compile. After 24hrs waiting, I gave up. Ok I realise that the grammer needs to split. Is there any _small_ examples out there, that demonstrates this technique for a beginner ? In my case I have one grammer and ~70 rules. Take the following rule: rule<ScannerT, string_closure::context_t> identifier ; identifier = lexeme_d [ (alnum_p || ch_p('_')) >> *(alnum_p || ch_p('_')) ] [ identifier.name = construct_<std::string>(arg1, arg2) ] ; What is the technique for converting it into a grammer, that is separately compiled ? Also how would I reference it again, without including the header file, from another rule dotPath = ( str_p(".") >> +( str_p("/") >> identifier ) ) [ dotPath.name = construct_<std::string>(arg1, arg2) ] ; Any help would greatly appreciated. Best regards, Ta, Avi

3 2

[data_time] Are posix_time functions reentrant ?
by Ruediger Berlich 21 Jul '09

21 Jul '09

Hi there, here is a question I didn't find answers on in the documentation: Are the posix_time functions reentrant ? In particular: In my library a number of threads instantiate objects that internally measure the elapsed time like this: // Measure the start time ptime startTime = boost::posix_time::microsec_clock::local_time(); // [...] // Has a time-out been set and if so, have we exceeded it ? if(firstTimeOut_.total_microseconds() && ((microsec_clock::local_time()-startTime) > firstTimeOut_)) { // do something } Best Regards, Ruediger

2 1

A question on member functions in a class using lambda expression? Can anyone with kindness help me?
by fmingu 21 Jul '09

21 Jul '09

I am using Dev-C++ 4.9.8.0,with lambda expression: ...................... class A{ ............. int result; double function2(const int& n) ......................... double function3(const int& Q,const int& N) ...................... double function1(const int& q, int& n){ double result=0.0; int loopvalue=0, totaltime=n; n%=q; ++thenumbern; ( for_loop(var(loopvalue)=0,var(loopvalue)<=var(totaltime),++var(loopvalue), var(result)+=( bind(&A::function2,_2)*bind(&A::function3,_1,_2))))(q,n); return result; } But the complier told me that: ............................... \boost\lambda\detail\select_functions.hpp instantiated from `Arg::sig<boost::tuples::tuple<A&,................. instantiated from `RET boost::lambda::lambda_functor_base<boost::lambda::forloop_action, Args>::call(A&, B&, C.................... \boost\lambda\detail\lambda_functors.hpp instantiated from `T::sig<boost::tuples::tuple<A&, B&, boost::tuples::null_type, boost::tuples::null_type, ............... instantiated from here By the way, is the result in var(result) the double result in function1 or the int result in class A? Can any one with kindness help me?

3 3

[asio] async_resolve problems
by Roman Shmelev 21 Jul '09

21 Jul '09

Hi! I've written _test_ dummy service, working in single thread (prototype for more useful app). It accepts strings like "google.com" (and "gosdkfjslfjle.com"), resolves them and returns ip of the host. I noticed, that bad hostnames make it think too much, preventing other requests from being processed. So, I decided to use async_resolve approach, hoping that now I will be able to handle many requests concurrently. But it seems that async_resolve is not as async as desired - it feels like separate thread resolves in sync way all hosts. The question is - how to make async_resolve be really async? Am I missing something?

3 3