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

trim() erroring out?
by Michael Wieher 02 Apr '08

02 Apr '08

/usr/include/boost/algorithm/string/trim.hpp:366: instantiated from 'void boost::algorithm::trim(SequenceT&, const std::locale&) [with SequenceT = char*]' datad/datarequest.cpp:32: instantiated from here /usr/include/boost/algorithm/string/trim.hpp:121: error: request for member 'erase' in 'Input', which is of non-class type 'char*' .. I'm passing trim() a char * ... seems like that doesn't make it happy, though?

2 1

Boost.Regex vs. Boost.Spirit
by Boris 02 Apr '08

02 Apr '08

Can anyone tell me why Boost.Spirit (which reuses Boost.Regex for regular expressions) works while the code below where Boost.Regex is used directly can not be compiled? std::string in = "test"; boost::wregex expr(L"test"); boost::match_results<std::string::const_iterator> what; boost::regex_search(in, what, expr); // COMPILER ERROR std::string out; boost::spirit::rxstrlit<wchar_t> expr2(L"test"); boost::spirit::parse(in.c_str(), expr2[boost::spirit::assign_a(out)]); The basic problem is of course that the regular expressions are based on wchar_t while the input string is based on char. Thus I'm not so much surprised why Boost.Regex does not work. I'm much more surprised though that my compiler (VC++ 2008) doesn't report an error with the code above which uses Boost.Spirit. I don't know why the code using Boost.Spirit compiles (is this implementation-dependent or guaranteed behavior)? It would make using regular expressions in templates much easier though as regular expressions don't seem to depend on the Char type of strings (assuming this is a feature I can rely on)? Boris

2 3

1.35.0 - what is the correct tag in SVN?
by Andrey Tcherepanov 02 Apr '08

02 Apr '08

Hello! I am wondering by what tag or branch (besides "release") (or just version) I can retrieve exatly same snapshot that was used for 1.35.0 from Subversion? Previous releases are available by RC_* tags, so I am wondering which one is used for 1.35? As general comment - may be is a good idea to have top "branch" called "releases" and then all packaged releases under it, so it is easier to find them in one place instead of going trhough all new and old working folders under branches subtree? Thank you very much, Andrey

3 5

Need boost's help with poor design
by Robert Dailey 02 Apr '08

02 Apr '08

Hi, Currently I'm using Boost.Signals to transfer Packet objects to subscribers. Right now my Boost.Signal looks like below: boost::signal<void (Packet const& p)> Right now Packet is the base class for several other packet types, each having the specific data a subscriber needs access to. Of course, given this design, the only way to obtain the data is to perform a downcast via static_cast or dynamic_cast: WalkPacket const& wp = static_cast<WalkPacket const&>( p ); // 'p' here is a generic Packet object. This is obviously bad design since it isn't type safe at all. It's also repetitive and tedious since each subscriber must duplicate the logic to perform the downcast. I'm wondering if there's anything in Boost you guys can suggest that I use to make this a little better. I would prefer to have a common Signal object that can take differently typed Slot objects. For example, I want to pass in a slot that looks like: "void (WalkPacket& p)" and have the signal utilize implicit conversions or something. Templates aren't even being used here because I can't find a way to fit them in, since everything is being done at runtime and not compile time. Keep this important note in mind: The type of the packet that will be dispatched to subscribers can only be known at compile time via a factory method. Data is received from the network, and that data is packed into the correct packet and returned as a Packet* base class pointer, so that we can transfer the data to subscribers through a common interface.

8 55

boost::regex - how to do a search_rev() ?
by fxplus 02 Apr '08

02 Apr '08

Hi all, String classes usually have a search_rev() function to start search from the rightmost end. Is it possible to do such a search using boost::regex? I need to find out if a text buffer (usually of size in hundreds of MBs) has certain sequences in the end. Thanks. -- Fab Ximi

2 1

serialize a boost::array
by Hansi 02 Apr '08

02 Apr '08

Hello, I have a question regarding to serialize a boost::array. I have searched in the headers of serialize but I can't find some header which I can include to solve the problem. Is there a header availaible in boost 1.34.1? Best regards Hansjörg

1 0

Memory debugging
by Sharad Mittal 02 Apr '08

02 Apr '08

Hello, I am writing an application using mingw and boost (threads, multi-index, etc). I am searching for a memory debugger (leaks, buffer overruns) for this configuration. 1) I tried duma but not sure how to use it. It kept stopping in a "new" call inside boost. 2) couldn't get dmalloc to run properly. Error "dmalloc library has gone recursive". Has anyone used any memory debugger reliably with mingw and boost? Thanks, Sharad

2 1

Re: [Boost-users] serial programs + other IO types?
by Daniel Lidström 02 Apr '08

02 Apr '08

> > > On Mon, Mar 31, 2008 at 9:13 PM, Tim Michals > <tcmichals(a)msn.com> wrote: > > >> There is a new project on sourceforge ASIO > > >> http://sourceforge.net/projects/rs232basedonasi/ that > is serial based... it > > >> is coming online soon... > > > This is great! I would like to see some tutorials/documents on how to implement other IO types within the ASIO framework. For example, we communicate with CAN-based devices and it would be extremely useful (I think) to do this with ASIO. Is ASIO limited to IO only? For example, I can think of an asynchronous "event" that listens to changes in the filesystem. It seems this could be implemented in much the same way as IO types within ASIO. What do you think? -- Daniel

1 0

BoostCon'08 Early Registration Deadline
by David Abrahams 02 Apr '08

02 Apr '08

Reminder: early registration for BoostCon'08 closes Monday, April 7. It's still not too late to avoid the late registration fee for what may be the finest C++ event of 2008. For the 2nd annual Boost C++ libraries conference, we've put together a fantastic program crowned by a keynote address from Bjarne Stroustrup. In addition to existing Boost libraries, we're covering technology of interest to any C++ developer trying to stay on the cutting edge, including hands-on sessions with features from the upcoming 2nd version of the C++ standard. This year we've also added a collection of short "author's corner" sessions for those of you who want an inside perspective on how advanced libraries are developed. See http://www.boostcon.com/program for details. BoostCon 2008 will be hosted at Aspen Center for Physics, one of the most beautiful meeting sites in the world, and a great venue for collaboration and discovery. The combination of a relaxed pace and intense inquiry made BoostCon'07 an event to remember, and we expect no less for this year. Please visit http://www.boostcon.com/registration to register. Thanks! -- The BoostCon Planning Committee David Abrahams Joel de Guzman Jeremy Siek Beman Dawes Eric Niebler Matthias Troyer Jeff Garland Sean Parent

1 0

Dijkstra in a multi-graph (parallel edges)
by Ioannis Nousias 01 Apr '08

01 Apr '08

Hello, I'm using dijkstra_shortest_paths() in a multi-graph, which seems to work fine. Via the predecessor map I get the vertices in the shortest path. However, how do I get the edges of the shortest path, bearing in mind this is a multi-graph (has parallel edges)? thanks Ioannis PS: is this the right mailing list to ask these sort of questions ? -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336.

2 2