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RE: [Boost-users] [BLL] How to search in a list for an object comparing a data member?
by Ben Hutchings 01 Nov '03

01 Nov '03

Gianluca Silvestri <gianluca.silvestri(a)maior.it> wrote: > Hi all, > What I want to achieve is a code similar to this: > > struct Foo { int fDataMember;} > > int main() > { > std::vector<Foo> foos; > Foo fo; > std::find_if(foos.begin(), foos.end(), _1->fDataMember == > fo.fDataMember); //<-- won't compile; } Well, apart from the missing semi-colon, missing includes and missing closing brace, I imagine you're having trouble with "_1->fDataMember". This is a documented limitation of the lambda library - there is no way to defer lookup of member names (overloading -> just changes the type and value of the pointer used) so member access can't be done on a placeholder. > I know I could use a functor object but this is just an example for a > more general need. Sorry, you'll have to define functors. These template functor classes might be useful: template<typename C, typename V, const V C::* P> struct lookup_member_const { const V & operator()(const C & c) const { return c.*P; } }; template<typename C, typename V, V C::* P> struct lookup_member { V & operator()(C & c) const { return c.*P; } }; Mind you, there might be similar things in Boost already.

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Build+Install+/Zc:wchar_t in Visual studio builds
by John Maddock 01 Nov '03

01 Nov '03

Guys, Rene's new Install code is working very well for me now, but I have a question about how we're building with Visual Studio .NET. Currently the vc7 and vc7.1 toolsets turn on /Zc:wchar_t unconditionally when building, however this is not the default option in current versions of the IDE, and of course the two options produce binary-incompatible libraries (at least as far as regex is concerned). How should we handle this? At the very least I would like to see a bjam option to turn off /Zc:wchar_t, but how should we be building the libraries by default: turning native wchar_t support on is the standards conforming way, but not currently the default Visual Studio way, or the way many third party libraries (like ICU for example) are built. Does anyone know how this option interacts with MFC/ATL/VisualForms etc? We could of course create a new build variant to handle this, but with 8 regex lib/dll variants already I'm not keen to add another 8 (apart from anything else testing already takes too long). I'm cross posting this to the Boost.users group as well, since whatever resolution we take will affect them the most :-) Thanks, John.

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[newbie] creating a (complex?) C++ wrapper around a C function call...
by Jason House 31 Oct '03

31 Oct '03

I want to create a wrapper function template <class foo> op_pk_fd_set_class(packet *packet, int index, foo &value, int simulated_bits); around the following function... (in OPNET) op_pk_fd_set( packet* pkptr, // same as in wrapper int index, // same as in wrapper int some_constant, //OPC_TYPE_STRUCT void* value, int simulated_bits, // same as in wrapper void* (*copy_proc)(void* obj_to_copy,int alloc_size), void (dealloc_proc*)(void *obj), int alloc_size); I believe dealloc_proc can just be a function pointer to the destructor. I could very well be mistaken, but I believe that a normal constructor takes only one parameter. I also think alloc_size should be sizeof(foo). I do not know how to obtain function pointers for constructor and deconstructor member functions. Any assistance I could get would be appreciated.

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RE: [Boost-users] Re: Build+Install+/Zc:wchar_t in Visual studio builds
by Ben Hutchings 31 Oct '03

31 Oct '03

Edward Diener <eddielee(a)tropicsoft.com> wrote: > John Maddock wrote: > > Guys, > > > > We could of course create a new build variant to handle this, but > > with 8 regex lib/dll variants already I'm not keen to add another 8 > > (apart from anything else testing already takes too long). > > I think you have to do this John if you want to support both the C++ > wchar_t and the MS wchar_t in Boost libraries. Although there are > VC++ predefined macros, _WCHAR_T_DEFINED and _NATIVE_WCHAR_T_DEFINED, > which are defined when /Zc:wchar_t is used, they are also stupidly > defined, according to the documentation, when typedef unsigned short > wchar_t is used ( talk about idiotic MS decisions ). That appears to be a documentation bug. I checked this in VC++ 7.1 and _NATIVE_WCHAR_T_DEFINED is not defined by <cstddef>. There is no sign of a #define _NATIVE_WCHAR_T_DEFINED in the headers for version 7.0 or 7.1. > So Boost needs to use a macro which the end-programmer must define > which tells whether or not /Zc:wchar_t is being used or not, and > create another set of libraries accordingly. Even in the absence of a macro, this test works: #include <cstddef> #include <iostream> #include <ostream> #include "boost/type_traits.hpp" int main() { std::cout << "/Zc:wchar_t was "; if (!boost::is_same<wchar_t, __wchar_t>::value) std::cout << "not "; std::cout << "used\n"; }

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RE: [Boost-users] vc++
by Ben Hutchings 31 Oct '03

31 Oct '03

adel.essafi <adel.essafi(a)laposte.net> wrote: > is it possible to compile boost project directly with vc++ 6.0 without > using commande lines. if yes how? Yes - in the IDE, create a "makefile" project and enter the command lines and targets in the project settings. It would be nice to have project files included in the distributed source, but unfortunately the file format is different for every IDE and for every different version of the Visual C++ IDE so it would be difficult to keep them all up-to-date. Ben.

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[BLL] How to search in a list for an object comparing a data member?
by Gianluca Silvestri 31 Oct '03

31 Oct '03

Hi all, What I want to achieve is a code similar to this: struct Foo { int fDataMember;} int main() { std::vector<Foo> foos; Foo fo; std::find_if(foos.begin(), foos.end(), _1->fDataMember == fo.fDataMember); //<-- won't compile; } I know I could use a functor object but this is just an example for a more general need. Thanks, Gianluca

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vc++
by adel.essafi 30 Oct '03

30 Oct '03

hi list is it possible to compile boost project directly with vc++ 6.0 without using commande lines. if yes how? thanks Accédez au courrier électronique de La Poste : www.laposte.net ; 3615 LAPOSTENET (0,34/mn) ; tél : 08 92 68 13 50 (0,34/mn)

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Linker problem using boost::regex with VC6.5
by Sven Van Echelpoel 29 Oct '03

29 Oct '03

Hi, I'm having a strange problem when I try to include boost::regex in my project (VC6.5 on Win2K). I'm not using Build to build a separate regex dll but rather include the source files directly in the project (or rather in a small utility static library). I've defined BOOST_REGEX_STATIC_LINK to avoid __declspec( dllimport ) / __declspec( dllexport ). Although everything compiles just fine the linker complains that it cannot find the library boost_regex_vc6_mdsd.lib. Further investigation revealed that it is actuallty listed somewhere as an additional default library (the linker outputs this when you switch on link progress messages). Searching through the sourcecode for #pragma comment( lib, ... ) and #pragma comment( linker, ... ) directives came up empty as did a search for boost_regex_vc6_mdsd.lib in all sources and headers. I got it to link by letting the linker ignore boost_regex_vc6_mdsd.lib. Even so I still would like to know where this is comming from. Any ideas? Sven

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RE: [Boost-users] Linker problem using boost::regex with VC6.5
by Sven Van Echelpoel 29 Oct '03

29 Oct '03

Sven Van Echelpoel wrote: [...] > Are you sure that that's defined for all translation units that use or > implement Boost.Regex? Yep. Double checked it now and it is defined at the project level for every project [...] >> Searching through the sourcecode for >> #pragma comment( lib, ... ) and #pragma comment( linker, ... ) >> directives came up empty as did a search for boost_regex_vc6_mdsd.lib >> in all sources and headers. > > It's in "boost/regex/v3/regex_library_include.hpp". Found it. I can now see I need to define the guard macro BOOST_REGEX_NO_LIB to disable the auto-linking. Doing so makes everything build just fine. Thanks, Sven

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CEST timezone conversion, boost date_time
by Erik Thiele 29 Oct '03

29 Oct '03

hi. i am trying to convert between UTC and CEST/CET (Europe/Berlin) i don't find documentation or suitable functions in the Wiki, the examples or the documentation. also i don't understand the sourcecode of the time zone stuff. but i found that eu_dst_trait exists, but don't know what that is and how to use it. any ideas? cu & thx erik -- Erik Thiele

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