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[iostreams] building iostreams with zlib support for iphone
by Kenny Riddile 09 Apr '09

09 Apr '09

I need to build the iostreams library with zlib support for both the iphone and iphone simulator. I already know how to just build the libs for iphone and the simulator, but I'm a windows developer and have little dev experience on mac, let-alone iphone, so I'm a bit bewildered. How do I go about getting zlib support compiled in?

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different member function signatures based on class template arguments
by Hicham Mouline 09 Apr '09

09 Apr '09

Hello, I have a long chain of calls of functions where a template argument is passed from 1 function to the next. Different template arguments required slightly different arguments in the following signature: template< typename Interp> struct InterExtrap { static void Process( xbegin, xend, x, AdditionalArguments<Interp> ); // this calls static function inside Interp }; AdditionalArguments<Interp> is: . empty for a couple of Interp . size_t for a couple of others . double d0, double d1 for a couple of others. If all cases had exactly 1 argument which varied, I would have done above: typename AdditionalArguments<Interp>::type I could do struct S { double d1; double d2; }; I have in mind optimization issues as well as many of these intermediate functions are inlined. So I am concerned about process(xbegin, xend, x, const S& s) // then access s.d1 and s.d2 as I measured it is slower than process(xbegin, xend, x, double d1, double d2) Initial function (specifies Interp and therefore knows whether to pass empty, or size_t, or double double) calls a number of intermediate functions that are not interested in this detail, but still have the Interp template argument, and finally call static functions inside Interp which then know what they require as arguments. Is it possible to write the intermediate functions (member of template classes) in a generic way? Would SFINAE or the sizeof trick or any MPL Fusion facility allow this? Regards,

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default argument and call trait const_reference
by Hicham Mouline 09 Apr '09

09 Apr '09

Hello, I have the following template template<typename C> class X { public: template<typename Interp, typename Extrap> void Get (int, typename boost::call_traits<Interp>::const_reference= Interp(), typename boost::call_traits<Extrap>::const_reference= Extrap() ) const; }; template<typename C> template<typename Interp, typename Extrap> inline void X<C>::Get(int, typename boost::call_traits<Interp>::const_reference i, typename boost::call_traits<Extrap>::const_reference e ) { // when I get here, i.mOrder is not 2 (0) e.mOrder is not 2 (23142343) } class P { public: static const size_t defaultInterpolationOrder = 2; // quadratic polynomial Polynomial1D(size_t order =defaultInterpolationOrder) : mOrder(order) {} Private: size_t mOrder; }; 1 example of call is x.template GetSpot<P,P>( 5 ); when I debug this P's ctor is never called and mOrder is never 2 Is my GetSpot method valid, the construction of the temporary should be bound to the const ref const P& and the temporary should have finished being constructed before we go inside the Get() method. Is there an issue with the definition of Get being out of classe? Am I calling call_traits<P>::const_reference in a wrong way? VS2005SP1 Regards,

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[mpl] register types in a mpl sequence type
by Thomas Lemm 09 Apr '09

09 Apr '09

All, I am trying to accomplish a compile time type registry by trying to register a specific subset of my classes into an mpl sequence type. So during compilation that sequence type should hold a sequence of my classes for subsequent processing (e.g. by mpl::for_each). An example: --- code start -------------- class Super { tyedef mpl::list<> SubTypesList; // usage of SubTypesList: printSubtypes() { mpl::for_each< SubTypesList >( ... )}; }; class A : public RegisterWith< A, Super > {}; class B : public RegisterWith< B, Super > {}; --- code end -------------- now Super::SubTypesList should be equivalent to mpl::list< A, B >. I have the feeling that this approach is not achievable with templates alone due to the C++ template mechanism not being able to redefine a type. Still I would be happy being proven wrong. Any pointers to similiar problems and solutions, alternative approaches (maybe using the boost_pp?) are welcome, too. Kind regards Thomas Lemm

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Re: [Boost-users] Linking with dynamic boost thread library
by John Wilkinson 09 Apr '09

09 Apr '09

> If the program compiles and runs the same only based on whether boost*.lib > is there, what function does the boost*.dll serve The boost*.lib files, as I think someone said earlier, are the import libraries for the boost*.dll run-time libraries. These are what you link to, in order to use boost*.dll at run time. The DLL files do not need to be in the link path, only in the executable path when your program is run. The boost*.lib files need to be in the link path when you build your program. John

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[lambda] how to get rid of the reference argument in lambda functor?
by Pobinger Gerhard Stefan 09 Apr '09

09 Apr '09

Hi *, I was desparately trying to compile something like this (VS2008), always getting the error that it cannot convert from int* to int*&. :boost::shared_ptr<int> c; ::boost::lambda::var(c) =::boost::lambda::constructor <::boost::shared_ptr<int>>() (::boost::lambda::new_ptr<int>()() ) [This is "short form" for the conventional code ::boost::shared_ptr<int>c=::boost::shared_ptr<int>(new int());] (1) The reason is that all lambda functors take arguments by reference. In this case, make_const in front of shared_ptr did not solve the problem, it causes immediate evaluation of the new_ptr functor... Is there any way to rewrite this (1) short line of code in boost-lambda? /Gerhard Pobinger

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Re: [Boost-users] Linking with dynamic boost thread library
by Steven Watanabe 09 Apr '09

09 Apr '09

AMDG Green, Jason M NSWCDL, W33 wrote: > I have a directory in my project call Boost. I added the directory to the > library files list. > In this directory I have the libboost*.lib files and the boost*.dll files. > I am able to get it working with no problem if I only have the libboost*.lib > files in there. If I rename them, and add the dll into the directory, it > will not build. That is where it will give me the error saying that it is > looking for libboost*.lib > Whoa. I'm confused. Is the linker complaining about libboost*.lib or boost*.lib? If you define BOOST_ALL_DYN_LINK or BOOST_<library name>_DYN_LINK the compiler will look for the import libraries for the dlls. > Green, Jason M NSWCDL, W33 wrote: > >> the compile warns me that it "cannot open file >> 'boost_regex-vc80-mt-gd-1_38.lib'" >> >> In Christ, Steven Watanabe

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[interprocess] warning C4251: need dll-interface
by Brent Arias 09 Apr '09

09 Apr '09

I've defined a class to use within shared memory, and I've decorated it with a Windows _declspec(export) to expose it from a DLL. When I compiled with VC 2008, I got this warning: Warning C4251: class 'boost::interprocess::vector<T,A>' needs to have dll-interface to be used by clients of 'MyClass' I searched boost user archives for any discussion of this, and in the context of boost.signals I've seen someone comment to simply disable the warning with: #pragma warning (disable: 4251) Std::list<OtherClass*> talkers; #pragma warning (default: 4151) Does this also apply to boost.interprocess? Is it really safe to ignore this warning and continue to use the interprocess code from within a DLL? Brent Arias

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Concept DefaultConstructible vs type traits has_trivial_constructor
by Hicham Mouline 09 Apr '09

09 Apr '09

Hi, What is the difference between the 2? For a type T, can it be DefaultConstructible and has_trivial_constructor<T> is false? Rds,

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Re: [Boost-users] boost build interface
by Rudolf Leitgeb 09 Apr '09

09 Apr '09

FWIW this doesn't have to be a windows only GUI. We could use the QT widget set and make this portable to most platforms supported by boost. Note, that Qt is LGPL now, so you could even include this into commercial distributions if needed. Am 08.04.2009 um 16:10 schrieb Green, Jason M NSWCDL, W33: > Not that I am volunteering, but it isn't that hard to come up with a > simple > dialog based mfc project that would set up the commands to properly > run the > boost build.

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