August 2002 - Boost-users - lists.preview.boost.org

[BGL] undirectedS self-loop add_edge assertion
by Chris Russell 27 Aug '02

27 Aug '02

Just a quick mention: A call to add_edge with u == v causes an assertion if Directed == undirectedS. adjacency_list.hpp line 843: assert( u != v ); // don't allow self-loops ^- boost_1_28_0 Avoiding the assertion is easy enough but this is inconsistent w/section 14.1.1 p.220 of the BGL book: "... Also if u and v are descriptors for the same vertex (creating self loop) and the graph is undirected, then the edge will not be created and the flag will be false." Am having tons of fun - the BGL and the book are super. Thanks! - Chris

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lambda library usage
by khuroth 27 Aug '02

27 Aug '02

I have a View class that has some widgets, and a Controller class that controls the view, so the View class has a GetController() member function that returns a reference to its controller. When the View's constructor is called, GetController() would return a bad ref, but it would return a valid reference by the time a button is clicked... so what I'm trying to do is, inside the View constructor: my_button.on_click = bind( (_1 ->* &A::GetController).DoSomething(), this ); but that obviously doesn't work... I'm even having trouble just saving the first part: my_button.on_click = bind<Controller&>(_1 ->* &A::GetController, this); also doesn't work... I tried defining the on_click member of the button as a boost::function<void> or a boost::function0<void> in the first example, and a boost::function<Controller&> or boost::function0<Controller&> in the second snip... I get immense compiler errors, so I'm not sure where I messed up. What am I doing wrong?

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shared_ptr swap problems
by Olaf Petzold 27 Aug '02

27 Aug '02

Hello, I've trouble with the follwong snippet: #include <iostream> #include <boost/shared_ptr.hpp> struct A { A(const char* n) : name(n) { } const char* name; }; struct B : public A { B(const char* n) : A(n) { std::cout << "construct " << name << std::endl; } ~B() { std::cout << "destruct " << name << std::endl; } }; struct BaseC { virtual void set(const boost::shared_ptr<A>& ptr) = 0; }; struct C : public BaseC { C() : b( new B("C::b") ) { } void set(const boost::shared_ptr<A>& ptr) { b.swap( boost::shared_static_cast( ptr ) ); // L21 } void print() { std::cout << b->name << std::endl; } boost::shared_ptr b; }; using namespace std; int main() { boost::shared_ptr<A> b( new B("b") ); C c; c.print(); c.set( b ); c.print(); } t.cc: In member function `virtual void C::set(const boost::shared_ptr<A>&)': t.cc:21: no matching function for call to `boost::shared_ptr::swap(boost::shared_ptr)' /usr/include/boost/shared_ptr.hpp:234: candidates are: void boost::shared_ptr<T>::swap(boost::shared_ptr<T>&) [with T = B] I did try boost::shared_polymorphic_cast to get a std::bad_cast exception - but it doesn't compile too. How can get it working? Thanks Olaf

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RE: [Boost-Users] How can checkout the files in Attic (hidden) fr om the cvs server?
by Jim.Hyslop 27 Aug '02

27 Aug '02

> I'm using WinCvs to checkout the current version of boost from the > cvs server. However, I found that I can not checkout some of the > libs which are put in the Attic, though I can browse them through my > internet browser. Anyone knows how to check these files out? (for > example, the mpl lib) Any files in the Attic are either obsolete, or have been added only on a branch and have not been merged to the trunk yet. Unless you are having a specific problem that requires a file from the Attic, then don't worry about what's up there (I suspect that's probably why it's called the "Attic" - out of sight, out of mind ;-) -- Jim

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How can checkout the files in Attic (hidden) from the cvs server?
by li_lirong 27 Aug '02

27 Aug '02

I'm using WinCvs to checkout the current version of boost from the cvs server. However, I found that I can not checkout some of the libs which are put in the Attic, though I can browse them through my internet browser. Anyone knows how to check these files out? (for example, the mpl lib) Thanks in advance, Lirong

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boost::any and operator ==
by billrobertson42 27 Aug '02

27 Aug '02

How do I compare two boost::any values for equality? How to I compare two containers of boost::any's for equality? Why doesn't boost::any define this operator? There has to be a reason. Thanks!

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What's your wish list?
by Kevin S. Van Horn 26 Aug '02

26 Aug '02

I'm teaching a graduate class on generic programming this semester, and I'm looking for some solid, meaningful projects for my students. If there are extensions to existing Boost libraries that you would like, or some new C++ library that you would like written, please contact me. -- Kevin S. Van Horn kevin.vanhorn(a)ndsu.nodak.edu

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Using Hash with Graph
by Sandeep Bhutani 26 Aug '02

26 Aug '02

Hi, I am trying to use hash feature with the graph library. Here are the various details: Solaris: SunOS 5.7 Compiler: KAI 4.0 STL: Native Sun Hash: A hacked up version of SGI/STLPort I can get graph to work with vectors/lists. I can't get it to work with the hash_set or hash_map. I get a message from the "concept_checks.h" file in my hash which essentially tells me that the hash function is not defined. I am reproducing the message from the compiler at the bottom. I am trying to make all this work by using the adjacency_list.cpp file in the examples directory. Here is the change I have made to that file: typedef adjacency_list<hash_setS, listS, undirectedS, VertexProperty, EdgeProperty> Graph; // New typedef adjacency_list<vecS, listS, undirectedS, VertexProperty, EdgeProperty> Graph; // Old Can you please help? Has anyone used the has feature in the graph library. I had to edit the line number 166 in adjacency_list.hpp to replace hash_set with hash_map. Thanks -Sandeep The message: "/lsi/home/bhutani/hash/include/concept_checks.h", line 289: error: call of an object of a class type without appropriate operator() or conversion functions to pointer-to-function type return __f(__arg); ^ detected during instantiation of "_Ret _STL_UNARY_FUNCTION_ERROR<_Func, _Ret, _Arg>::__unary_function_requirement_violation(_Func &, const _Arg &) [with _Func=std::hash<boost::detail::adj_list_gen<boost::adjacenc y_list<boost::hash_setS, boost::listS, boost::undirectedS, boost::property<boost::vertex_index_t, size_t, boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>, boost::listS, boost::hash_setS, boost::undirectedS, boost::property<boost::vertex_index_t, size_t, boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>::config::StoredEdge>, _Ret=size_t, _Arg=boost::detail::adj_list_gen<boost::adjacency_list<boos t::hash_setS, boost::listS, boost::undirectedS, boost::property<boost::vertex_index_t, size_t, boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>, boost::listS, boost::hash_setS, boost::undirectedS, boost::property<boost::vertex_index_t, size_t, boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>::config::StoredEdge]" at line 95 of "adjacency_list.cpp" 1 error detected in the compilation of "adjacency_list.cpp". KCC: Compilation failed. boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>, boost::listS, boost::hash_setS, boost::undirectedS, boost::property<boost::vertex_index_t, size_t, boost::property<boost::vertex_color_t, boost::default_color_type, boost::no_property>>, boost::property<boost::edge_name_t, std::string, boost::no_property>, boost::no_property, boost::listS>::config::StoredEdge]" at line 95 of "adjacency_list.cpp" 1 error detected in the compilation of "adjacency_list.cpp". KCC: Compilation failed.

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Had to change typename to class in template declaration of ref.hpp
by Matthias Kronenberger 26 Aug '02

26 Aug '02

Is that a known bug of MSVC? changing all the typename to class removed the error messages.

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Trouble with boost::bind
by stupid_newcomer 26 Aug '02

26 Aug '02

I'm trying to play with boost::bind and boost::mem_fn, however, i have some difficulties with the member function with more than 2 arguments. I have tried a number of time and gone through the documentation , but still can't found an answer. Example: #include <boost/shared_ptr.hpp> #include <boost/mem_fn.hpp> #include <boost/bind.hpp> #include <iostream> #include <vector> #include <algorithm> using namespace std; class B { public: void print0() const { cout << "B::print0 " << endl; } void print1(int i) const { cout << "B::print1 " < Ptr; vector<Ptr> v; for (int i = 0; i < 3; ++i) { v.push_back(boost::shared_ptr(new B())); } // zero argument, OK for_each(v.begin(), v.end(), boost::mem_fn(&B::print0)); // one argument, OK for_each(v.begin(), v.end(), boost::bind(&B::print1, _1, 5)); // two argument, how to call B::print2 ? // for_each(v.begin(), v.end(), /* B::print2 */); return 0; } Thanks for your help!

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regex_match question
by yg-boost-users＠m.gmane.org 25 Aug '02

25 Aug '02

hello everybody i have a trouble with regex_match function. when i try to match a string with a pattern like "(abc)*", and if the string beeng matched contains several subexpressions 'abc', regex_match returns only one match so that i can't iterate through all of them. so, it counts subexp's in the pattern, not in the string. why it happens (i use default flags for regex_match, which must perform what i expect)? and what is the solution to the problem (the one i found so far is to parse in 2 phases - once with regex_match to be sure that the whole string matched, and then to use regex_split. but i'd like to parse the string only once and obtain all the subexp's)? thanks in advance aram

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JAM and boost.pythyon
by sashan 24 Aug '02

24 Aug '02

Hi I've built the Python library and a few of my own test projects. I have problems when trying to link with an external library. Basically I get the 'unresolved external' link error. So I look at the jamfile I'm using and in the dependencies section add the following <dll>E:/code/Library/MyLib Then I run bjam again and the first error I get is E:/Code/Library/Jamfile: No such file or directory So I guess its looking for a Jamfile in that directory. Problem is I don't know what to put inside the Jamfile. Can someone please help? Thank you Sashan

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REGEX - expression doesn't match
by Fr�d�ric Mayot 24 Aug '02

24 Aug '02

Hi, My problem is really simple : I have several regular expressions (like (19[4-9]\d)|(200\d)|( [09]\d ) ) which work when they correspond to the entire string, e.g. : "2002" OK; "something 2002 something" NOT OK. Everythings worked fine with the GRETA library, and now, it doesn't. Does anyone have an idea ? Thanks. Fred

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Re: [Boost-Users] Re: REGEX - expression doesn't match
by dan.ellis＠sophos.com 23 Aug '02

23 Aug '02

> It's simple : I have a string and a regular expression. I only want to > find the FIRST sub-string which matches my regular expression (S), then > to extract the sub-string before S and the sub-string after S. Off the top of my head, it sounds like you want: (.+)(200\d)(.*) -- Dan Ellis, Software Engineer, Sophos Anti-Virus Email: dan.ellis(a)sophos.com, DDI: 01235 540204 Real Business/CBI Growing Business Awards: Company of the Year Tel: 01235 559933, Web: http://www.sophos.com/

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Graph - return edge_descriptor
by Shaw, Richard A 23 Aug '02

23 Aug '02

Can anybody tell my why the find_edge function in the code below fails to get a property if I return the first edge in the list. This is what happens - Find_edge looks for edge A - B It winds it and prints out the edge descriptor, and the weight of the edge It the returns the edge The main code prints out the edge descriptor and the fails when trying to print the weight. BTW - Is there a ready made function to find an edge based on the vertices ? #include <boost/config.hpp> #include <iostream> #include <fstream> #include <boost/graph/graph_traits.hpp> #include <boost/graph/adjacency_list.hpp> #include <boost/graph/dijkstra_shortest_paths.hpp> using namespace boost; // Find edge template <class Graph> std::pair<bool, graph_traits<Graph>::edge_descriptor> find_edge(graph_traits<Graph>::vertex_descriptor u, graph_traits<Graph>::vertex_descriptor v, Graph g) { graph_traits<Graph>::out_edge_iterator ei, edge_end; for (boost::tie(ei,edge_end) = out_edges(u, g); ei != edge_end; ++ei) { if (target(*ei, g) == v) { std::cout << "Inside " << *ei << " " << get(edge_weight, g, *ei) << std::endl; return std::make_pair(true, *ei); } } return std::make_pair(false, *ei); // Is there a null edge that I can return ? } int main(int, char *[]) { typedef adjacency_list < listS, vecS, directedS, no_property, property < edge_weight_t, int > > graph_t; typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor; typedef graph_traits < graph_t >::edge_descriptor edge_descriptor; typedef std::pair<int, int> Edge; const int num_nodes = 5; enum nodes { A, B, C, D, E }; Edge edge_array[] = { Edge(A, C), Edge(B, B), Edge(B, D), Edge(B, E), Edge(C, B), Edge(C, D), Edge(D, E), Edge(E, A), Edge(E, B) }; int weights[] = { 1, 2, 1, 2, 7, 3, 1, 1, 1 }; int num_arcs = sizeof(edge_array) / sizeof(Edge); #ifdef BOOST_MSVC graph_t g(num_nodes); property_map<graph_t, edge_weight_t>::type weightmap = get(edge_weight, g); for (std::size_t j = 0; j < num_arcs; ++j) { edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(edge_array[j].first, edge_array[j].second, g); weightmap[e] = weights[j]; } #else graph_t g(edge_array, edge_array + num_arcs, weights, num_nodes); property_map<graph_t, edge_weight_t>::type weightmap = get(edge_weight, g); #endif graph_traits < graph_t >::edge_descriptor e; bool found; std::cout << "List All" << std::endl; graph_traits < graph_t >::edge_iterator ei, ei_end; for (tie(ei, ei_end) = edges(g); ei != ei_end; ++ei) { std::cout << *ei << get(weightmap, *ei) << std::endl; } std::cout << "List Not First" << std::endl; tie(found, e) = find_edge< graph_t >(E, A, g); std::cout << "Outside " << e << get(weightmap, e) << std::endl; // This edge is OK std::cout << "List First" << std::endl; tie(found, e) = find_edge< graph_t >(A, C, g); std::cout << "Outside " << e << get(weightmap, e) << std::endl; // This line fails to get the weight return EXIT_SUCCESS; } Richard Shaw ¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø¤º°`°º¤ø,¸¸,ø¤º°`°º¤ø¤º°`°º¤ø,¸¸,ø¤ Atkins Transport Systems Woodcote Grove Ashley Road Epsom KT18 5BW Direct Dial.: +44 (0) 1372 756407 Switchboard: +44 (0) 1372 726140 Fax: +44 (0) 1372 740055 www.atkinsglobal.com/transportsystems <www.atkinsglobal.com/transportsystems> This email and any attached files are confidential and copyright protected. If you are not the addressee, any dissemination of this communication is strictly prohibited. Unless otherwise expressly agreed in writing, nothing stated in this communication shall be legally binding.

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RE: [Boost-Users] Re: boost::object_pool
by scleary＠jerviswebb.com 22 Aug '02

22 Aug '02

> -----Original Message----- > From: wugui [mailto:yg-boost-users@m.gmane.org] > > another question: > > how make boost::object_pool thread_safe? To make a pool object thread-safe, guard all access with a mutex. -Steve

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RE: [Boost-Users] boost::object_pool
by scleary＠jerviswebb.com 22 Aug '02

22 Aug '02

> -----Original Message----- > From: wugui [mailto:yg-boost-users@m.gmane.org] > > class A; > class B; > class AB : virtual public A, virtual public B; > > all destruct is virtual > > boost::object_pool<AB> pool_ab; > > B * pb = pool_ab.constuct(); > pool_ab.destroy(pb); // is this right? This looks right to me; what "pool_ab.destroy(pb);" does is: pb->~AB(); free(pb); // puts pb back in the free list of pool_ab -Steve

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Kai C++ for Linux and Solaris
by Wintermantel , Marc 22 Aug '02

22 Aug '02

Hi everybody, We really badly need the latest version available of Kai C++ Compiler for Linux and Solaris. If someone wants to sell his copy, please write me!!! We would really be grateful. Yours truly, Marc Wintermantel Marc Wintermantel IMES - Structures Technology ETH Zurich, LEO C4 Leonhardstrasse 27 CH- 8092 Zurich Tel. ++41 1 633 35 32 Fax. ++41 1 632 17 02 [Non-text portions of this message have been removed]

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boost::object_pool
by wugui 22 Aug '02

22 Aug '02

class A; class B; class AB : virtual public A, virtual public B; all destruct is virtual boost::object_pool<AB> pool_ab; B * pb = pool_ab.constuct(); pool_ab.destroy(pb); // is this right?

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boost lambda library compile error
by khuroth 21 Aug '02

21 Aug '02

I have searched already in this list and the dev list for these MSVC compiler errors, but none of the solutions have worked so far. I have turned off precompiled headers, built clean, tried defining BOOST_NO_MEMBER_TEMPLATES before including "boost/lambda/lambda.hpp" (or "boost/lambda/bind.hpp"), and I still always get this error under Visual C++ 6 SP5 (Win2k Pro SP3), in both the Debug and Release configurations: Deleting intermediate files and output files for project 'dWin - Win32 Release'. --------------------Configuration: dWin - Win32 Release--------------- ----- Compiling... dwin-button.cpp dwin-common-control.cpp dwin-dialog.cpp C:\TMP\BOOST\BOOST_1_28_0\boost/lambda/detail/lambda_fwd.hpp(31) : fatal error C1001: INTERNAL COMPILER ERROR (compiler file 'msc1.cpp', line 1794) Please choose the Technical Support command on the Visual C++ Help menu, or open the Technical Support help file for more information Not sure what I'm doing wrong..

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Boost Concept Check Library
by igor_bashkirov 21 Aug '02

21 Aug '02

Hello, I work on big software project that is ported to several platforms/compilers, including Linux,Solaris/GCC 2.95.2,3.0.4); Windows/MSVC 6.0; AIX/VisualAge; MacOS X / GCC 2.95.2 (Apple). Recently, I decided to make use of Boost library (v 1.28) and the first thing I tried was Boost Concept Check Library (BCCL). Unfortunately, the use of the library wasn't as smooth as I expected, namely, with respect to BOOST_CLASS_REQUIRES macro. Thus, I'd like to submit a couple of observations and one proposal regarding usage of this macro. Let's start with observations: following is the snippet from <boost/concept_check.hpp> header: [code // The BOOST_CLASS_REQUIRES macros use function pointers as // template parameters, which VC++ does not support. #if defined(BOOST_NO_FUNCTION_PTR_TEMPLATE_PARAMETERS) #define BOOST_CLASS_REQUIRES(type_var, concept) .... #else #define BOOST_CLASS_REQUIRES(type_var, concept) \ typedef void (concept <type_var>::* func##type_var##concept)(); \ .... end code] As you could see, BOOST_CLASS_REQUIRES macros evaluate to nothing if BOOST_NO_FUNCTION_PTR_TEMPLATE_PARAMETERS symbol is defined. But, to my great surprise, I didn't find any more references to BOOST_NO_FUNCTION_PTR_TEMPLATE_PARAMETERS symbol throughout the Boost library. Moreover, the above comment about VC++ not supporting function pointers as template parameters is wrong (at least for MSVC 6.0 with SP5). Not to be unfounded, I will provide following sample program successfully compiled and run under MSVC 6.0 with SP5: [code #include <iostream> using namespace std; typedef void(*FP)(); template <FP T> class X { FP fp_; public: X() : fp_(T) {} void print() const { cout << fp_ << endl; } }; void f() {} int main(int, char**) { X<&f> x1; x1.print(); return 0; } end code] The same is true for pointers to member functions of both ordinary and template classes. OK, this observation could be treated as "cosmetic" one, but the following won't. Let's look at the definition of BOOST_CLASS_REQUIRES macro: [code #define BOOST_CLASS_REQUIRES(type_var, concept) \ typedef void (concept <type_var>::* func##type_var##concept)(); \ template <func##type_var##concept _Tp1> \ struct concept_checking_##type_var##concept { }; \ typedef concept_checking_##type_var##concept< \ BOOST_FPTR concept <type_var>::constraints> \ concept_checking_typedef_##type_var##concept end code] and at a typical usage of this macro (taken from Boost documentation): [code template <class T> struct generic_library_class { BOOST_CLASS_REQUIRES(T, EqualityComparableConcept); // ... }; end code] Here, the "EqualityComparableConcept" is a concept checking class defined in the "boost" namespace. OK, that's great and works fine until "generic_library_class" is also declared in the "boost" namespace. Let's now suppose "generic_library_class" is declared in namespace "ns1". Then, BOOST_CLASS_REQUIRES macro evaluates to following: [code namespace ns1 { template <class T> struct generic_library_class { typedef void (EqualityComparableConcept <T>::* funcTEqualityComparableConcept)(); ... }; } end code] Did you see the problem places? Yes, it's where "concept" parameter of the macro is substituted for "EqualityComparableConcept". This name is not declared in the namespace "ns1"! The first itch could be to specify "boost::EqualityComparableConcept" as a value of the second parameter of the macro, but, "not so fast, Skywalker!" - in this case we will end up with "funcTboost::EqualityComparableConcept" name for the pointer to member function that is not a legal name of C/C++ identifier. Someone could say "What a big deal?! Just write 'using namespace boost;' or 'using boost::EqualityComparableConcept;' just before declaring 'generic_library_class'.". Well, the declaration of "generic_library_class" seems to be in the header, right? And what do you think about writing "using-directives" in header files? Yes, right, - it's evil! Especially for large production code. Just check your favorite C++ book. Though, the use of "using-declarations" in headers is a moot point, I also consider it as evil for the same reasons as for "using- directives". Anyway, "using-declarations" won't help us, - they just don't work under MSVC 6.0 in our case. So, what do we have, - "exclusive circle"? I hope not. Finally, I got to the proposal that should help us to eliminate defects of the macro and to obviate above-stated difficulties. What if to add one more parameter, say, "ns", to the BOOST_CLASS_REQUIRES macro to pass the name of the namespace the concept checking class belongs to? Let's look at the new definition of the macro: [code #define BOOST_CLASS_REQUIRES(type_var, ns, concept) \ typedef void (ns::concept <type_var>::* func##type_var##ns##concept) (); \ template <func##type_var##ns##concept _Tp1> \ struct concept_checking_##type_var##ns##concept { }; \ typedef concept_checking_##type_var##ns##concept< \ BOOST_FPTR ns::concept <type_var>::constraints> \ concept_checking_typedef_##type_var##ns##concept; end code] and at it's usage: [code namespace ns1 { template <class T> struct generic_library_class { BOOST_CLASS_REQUIRES(T, boost, EqualityComparableConcept); // ... }; } end code] that will evaluate to the following: [code namespace ns1 { template <class T> struct generic_library_class { typedef void (boost::EqualityComparableConcept <T>::* funcTboostEqualityComparableConcept)(); ... }; } end code] That's it. Moreover, this solution does not suffer from yet another drawback inherent to the original one, viz, name clashing when using in the same class concept checking classes with the same name, but from different namespaces. The only issue I could see with my suggestion was impossibility to use concept checking classes declared at the global scope, but, I hope nobody would think of such thing, because it's evil (sorry for repetition). I hope the proposed solution will increase usability of the BCCL. Best regards, Igor Bashkirov.

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Upgrade VisC++ compiler
by sen_al2002 20 Aug '02

20 Aug '02

Hi, I am a newbie to all this programmer stuff. I am a physics student doing some computer simulations. I was trying to use the special function atanh from boost libraries but couldn't. The error message reads d:\boost_1_28_0\atanh.hpp(77) : error C2989: 'atanh_helper1_t<T,0>' : template class has already been defined as a non-template class Some advised me to update my VisC++ ver 6.0 compiler. How can I do that? Does anybody out there have any better advise? Thanks sen

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boost python link error
by kiminkim 20 Aug '02

20 Aug '02

I want to export C++ class...use boost lib but link error occured... help me. #include <windows.h> #include <boost/python/class_builder.hpp> #include <string> namespace python = boost::python; class CBaseBox { public: CBaseBox() {}; void move(); private: std::string a; }; void CBaseBox::move() { MessageBox(NULL, "kkm", "kkm", MB_OK); } BOOST_PYTHON_MODULE_INIT(tuesday) { python::module_builder this_module("tuesday"); python::class_builder<CBaseBox> CBaseBox_class(this_module, "CBaseBox"); CBaseBox_class.def(&CBaseBox::move , "move"); } --------------------Configuration: tuesday - Win32 Debug-------------------- Compiling... export.cpp Linking... Creating library pyds\./tuesday_d.lib and object pyds\./tuesday_d.exp export.obj : error LNK2001: unresolved external symbol "class CBaseBox & __cdecl from_python(struct _object *,struct boost::python::type<class CBaseBox &>)" (?from_python@@YAAAVCBaseBox@@PAU_object@@U?$type@AAVCBaseBox@@@python@boost @@@Z) pyds\.\tuesday_d.pyd : fatal error LNK1120: 1 unresolved externals Error executing link.exe.

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Boost Python error handling
by cseymour＠interchange.ubc.ca 19 Aug '02

19 Aug '02

Here is a sample program which shows the problem i've been having (posted in earlier messages). When I import the module "sample" and run the function test(), I get the following output: This is a test Raising an error Aborted When I should get a message saying it caught the error, and then a Python error, instead of it Aborting and quitting Python. /* sample.c */ #include "Python.h" #include "boost/python/class_builder.hpp" namespace py = boost::python; void test() { std::cout << "This is a test" << std::endl; std::cout << "Raising an error" << std::endl; PyErr_SetString(PyExc_TypeError, "This is the error"); throw py::argument_error(); } BOOST_PYTHON_MODULE_INIT(sample) { try { py::module_builder this_module("sample"); this_module.def(test, "test"); } catch (...) { std::cout << "Caught an error" << std::endl; py::handle_exception(); } }

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Newbie and shared_ptr
by Ian Mold 19 Aug '02

19 Aug '02

I have been looking at the shared_ptr class, and I have made a change to include an assignment from a standard pointer. I have done this so that I don't have to create a new shared_ptr just to reassign an existing shared_ptr. // Assignment to a 'normal' pointer. shared_ptr & operator=(T * r) { this_type(r).swap(*this); return *this; } I have a few questions. 1) Is this necessary? 2) Does this do the job? 3) Is there any reason this wasn't included in the first place? I welcome any comments. Regards, IanM

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