December 2008 - Boost-users - lists.preview.boost.org

[bind] code sample crashing MS compiler
by Christian Henning 21 Dec '08

21 Dec '08

This following code sample will crash the MS compiler version 8. I hope there are some MS folks reading this mailing list, since I have no idea where else to post this. #include <boost/bind.hpp> struct A { void operator() () { boost::bind( &A::lookup, *this, unsigned char() )(); } void lookup( unsigned char& c ) {} }; int main(int argc, char* argv[]) { A()(); return 0; } I know the code is not suppose to compile. Uncommenting the this pointer in the bind construct will make the code compile fine. Regards, Christian

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[test framework] one testsuite over multiple translation units
by Georg Sauthoff 21 Dec '08

21 Dec '08

Hi, I am using the unittest framework from boost 1.34 and it is really usefull (starting with the BOOST_CHECK_EQ style macros are great, since they print out the values of the arguments, etc.). Currently I am using a set of testsuites, i.e. one testsuite consistst of one translation unit, and each translation unit is linked to the main from the boost test framework (utf). Thus I get n test executables for n testsuites. Is it possible (and/or intended) to link a set of different testsuites in different translation together to one test executable? I looked at different versions of utf documentation, but couldn't find something specific about this use case. Currently I am using utf for the single translation unit case like this: //testsuite_foo.cc #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MAIN #define BOOST_TEST_MODULE foo #include <boost/test/unit_test.hpp> BOOST_AUTO_TEST_CASE( foo_bar ) { } And to compile it: $ g++ testsuite_foo.cc -lboost_unit_test_framework How do you use the utf regarding to this aspect? Best regards Georg Sauthoff

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Re: [Boost-users] [boost] [review][constrained_value] Review of Constrained Value Library begins today
by Mika Heiskanen 21 Dec '08

21 Dec '08

Sebastian Redl wrote: > Mika Heiskanen wrote: >> Thank you for your explanation Peter. However, I do not see why an assert >> should be the first choice when a programming error can be detected by >> the program itself. For example, I would prefer my word processor >> to announce a programming error instead of producing a core dump. > And then what? The best thing it can do is do an emergency dump of the > currently open document and then abort. This is something a smart assert > can do as well. I thought we were comparing plain assert with exception handling. I would count a smart assert closer to the latter. > If you detect a programming error through violation of an invariant, > what can you do? If you know exactly what damage the error has caused > and you have enough information to fix all that damage, then you should > know the error well enough that you could have fixed it in the first > place. If you can't fix all the damage, anything except aborting the > program is a major data corruption waiting to happen. Precisely. The fact that an invariant is broken does not mean everything else is broken too, and that all the damage cannot be fixed. If it cannot, of course aborting is the best choice. We're probably comparing apples and oranges here. Perhaps it is pointless to continue this thread on how broken invariants should be handled, it will most likely always depend on the details of the case. What matters is that the reviewed library should enable exceptions as an error mechanism, which I think we all agree on, and I do not see why it wouldn't be the most common use case and hence the default action, which we may not agree on. I can live with that. Kind regards, --> Mika Heiskanen

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[C++] Boost::Regex beginner question
by P.C. 21 Dec '08

21 Dec '08

salutations, I'm a complete beginner in Regex++; I've downloaded it and installed it in Visual C++ 6.0, and it's functioning properly. the problem is that I searched all over the internet and I only discovered how to do basic matching operations and basic replacing. my doubt is the following: I want to know how to do search and replace regexp operations, like it can be done in Perl by using groups (expressions surrounded by parentheses), which allow to select the substrings, matched by the regexp, in the form of $1, $2, and so on. basically, the parentheses mark the matched expression for future reference (for example, for use in the replace operation). for example (Perl example): s/X(.*?)Y/XY$1/g; I'm not sure if this explanation of what I want is very clear. I would appreciate a straightforward example code. thank you in advance. -- View this message in context: http://www.nabble.com/-C%2B%2B--Boost%3A%3ARegex-beginner-question-tp210817… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [bind] Need Help - Function Composition
by loadcom 21 Dec '08

21 Dec '08

Hello Watanabe, I'm not sure if what you mean is that in your use case: boost::function f = make_less_by_func(boost::bind(...)); the temporarily constructed bind obj will go out of its lifetime before we use it via a refence to it? But if I cannot declare const F& func_; instead of F func_; then why bother using another ref lib? or, in other words, is there a way to save this 'unneeded' copy construction and allow us to use make_less_by_func(boost::bind(...)) ? btw, I'm not using ref lib frequently, but should boost::unwrap_ref be boost::unwrap_reference? Thank you so much for your continuous help and patience to my probable stupid questions. Best regards Max ----- Original Message ----- From: Steven Watanabe To: boost-users(a)lists.boost.org Subject: Re: [Boost-users] [bind] Need Help - Function Composition Date: 2008-12-21 02:39:38 AMDG loadcom wrote: > One step further, will the following version save one copy construction > in make_less_by_func()? > > template struct less_by_func > { > typedef bool result_type; > > const F & func_; > less_by_func(const F & func) : func_(func) {} > > template > bool operator()(const T& lhs, const T& rhs) const > { return func_(lhs) }; > > // helper function > template less_by_func make_less_by_func(const F& func) > { return less_by_func(func); } > I don't advise this in general because it requires the argument of make_less_by_func to survive for a while. boost::function f = make_less_by_func(boost::bind(...)); f(1, 2); // undefined behavior because of the dangling reference. If you really want this capability #include template struct less_by_func { typedef bool result_type; F func_; less_by_func(const F & func) : func_(func) {} template bool operator()(const T& lhs, const T& rhs) const { return boost::unwrap_ref(func_)(lhs) http://lists.boost.org/mailman/listinfo.cgi/boost-users ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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[MultiArray] Bound Guarding
by loadcom 21 Dec '08

21 Dec '08

Hello, I'm using boost::multi_array for a while and find it very powerful except one point that I cannot specify an array_view's number of dimentions at runtime. But this pity is not the topic of this post. You know one can create an array_view with arbirary given start/bound indices as well as the stride as follows: typedef boost::multi_array<T, 3> array_t; array_t myarray; //... typedef array_t::index_range range_t; typename array_t::array_view::view<2> myview = myarrray[boost::indices[range_t(0, 8, 2)][rang_t()][1]]; As I don't know in the internal of the lib how the dound guarding of iteration is done, either - in the 'standard' STL manner as i!=bound; or - in the 'conventional' C stale as i<bound my concern is in case that one advetently specify 'range_t(0, 8, 2)' as range_t(0, 7, 2), if this error cause undefined behavior, or is as save as it correct form, or, seemingly impossible, detected at runtime or even compile time? Thanks for any concern. Best regards Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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Re: [Boost-users] [bind] Need Help - Function Composition
by loadcom 20 Dec '08

20 Dec '08

One step further, will the following version save one copy construction in make_less_by_func()? template <typename F> struct less_by_func { typedef bool result_type; const F & func_; less_by_func(const F & func) : func_(func) {} template<typename T> bool operator()(const T& lhs, const T& rhs) const { return func_(lhs) < func_(rhs); } }; // helper function template<typename F> less_by_func<F> make_less_by_func(const F& func) { return less_by_func<F>(func); } Thanks again. B/Rgds Max Hello Watanabe, Your code works well. And it's much more generic and elegant than the original version. Thank you so much! Best regards Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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[accumulators] Need help
by Neal Becker 20 Dec '08

20 Dec '08

I'm trying to define an accumulator for complex types, abs_sqr. The test program is attached. I get an error from gcc-4.3.2 which I've never seen, and is not informative: test_acc.cc:39: error: argument dependent lookup finds ‘struct boost::accumulators::tag::abs_sqr’ test_acc.cc:48: error: in call to ‘abs_sqr’

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[C++] Problems with undirected_dfs and color maps
by Zemmerie 20 Dec '08

20 Dec '08

I'm trying to use an undirected_dfs to find cycles in a graph. I have a visitor all ready to go, but I'm having trouble with the actual undirected_dfs() call. It wants me to give it a vertex color map and an edge color map, and I think that's where my problem is coming from. I managed to get something that will compile, but when it runs, it goes to the root node, then to one connected to it, then back to the root node, and just repeats. I think what's happening is that the color maps aren't working properly, so it doesn't know that the root node has already been discovered. Can anyone take a look at this and let me know what I'm doing wrong and how I can fix it? At this point I'm about ready to just write my own dfs algorithm! Thanks -Kate #include <boost/graph/adjacency_list.hpp> #include <boost/graph/graph_traits.hpp> #include <boost/graph/undirected_dfs.hpp> #include <boost/property_map.hpp> #include <boost/graph/graph_archetypes.hpp> #include <iostream> #include "CycleFinder.h" using namespace boost; using namespace std; //easier access to common types typedef boost::adjacency_list<vecS, vecS, undirectedS> Graph; typedef boost::graph_traits<Graph>::vertex_iterator vertex_iterator; typedef boost::graph_traits<Graph>::edge_iterator edge_iterator; typedef boost::graph_traits<Graph>::vertex_descriptor vertex_descriptor; typedef boost::graph_traits<Graph>::edge_descriptor edge_descriptor; int ConstraintsSolver::reduceClusterGraph(Graph cluster) { //search for 6-cycles and reduce them pair<vertex_iterator, vertex_iterator> vertexPair = vertices(cluster); vertex_descriptor rootNode = *vertexPair.first; CycleFinder finder; read_write_property_map_archetype<vertex_descriptor, default_color_type> vertexColorMap; read_write_property_map_archetype<edge_descriptor, default_color_type> edgeColorMap; undirected_dfs(cluster, finder, vertexColorMap, edgeColorMap, rootNode); return 0; } -- View this message in context: http://www.nabble.com/-C%2B%2B--Problems-with-undirected_dfs-and-color-maps… Sent from the Boost - Users mailing list archive at Nabble.com.

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Re: [Boost-users] [boost.build] should we not define _SECURE_SCL=0 by default for all msvc toolsets
by Thorsten Ottosen 20 Dec '08

20 Dec '08

Neil Groves skrev: > Thorsten, > > On Thu, Dec 4, 2008 at 3:05 PM, Thorsten Ottosen < > thorsten.ottosen(a)dezide.com> wrote: > >> Dear all, >> >> Is there are reason why we do not compile with this flag set by default? >> Are there any users of Boost out there which actually wants the securuty >> mode turned on? >> > > I personally prefer to have _SECURE_SCL=0 in Release builds too. For users > that also have to build against other libraries that are provided as > precompiled binaries that use the MSVC defaults this would break things. The > _SECURE_SCL setting changes the ABI. > > >> If not, then I suggest that we change the build settings. >> > > I think it would be ok to allow both options, but probably the default > should equal the Microsoft default with an easy way to opt-out of the > madness! But AFAIK, even the prebuilt binaries that you get from Boost Consulting are built with _SECURE_SCL=0. -Thorsten

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