- Boost-users - lists.boost.org

Compress to buffer
by Kenneth Adam Miller 16 Jan '14

16 Jan '14

I have an object for which operator << is defined, myobj. I want to compress into a buffer, and I know that this can be done with boost. I would prefer a buffer that dynamically resizes, but that only allocates new space, preferably treating discontiguous space brought on by new allocations as though the whole buffer was one piece; I don't want to find that it's copying data at all. So vector won't work as a buffer; there's no need for it to be contiguous, just as fast as possible. I've been trying to do this with filtering_istreambuf by pushing a bzip2_compressor (any compression filter will work). So far, it's giving me a lot of trouble. I did find an example where a string was passed to a function, but they went through a process where they first moved the string into an stringstream. I don't want to settle for that extra copy either. What would be nice is to be able to do something like compressor << myobj compressor.buf(); //returns compressed myobj output

3 18

Boost.Heap (i.e fibonacci_heap) handle_type handles are persistent across calls?
by Tassos Souris 16 Jan '14

16 Jan '14

Hello to everyone When i use, say a fib_heap fb1 and fib_heap fb2. I add some data to fb1 using the push method and keep the handles returned from those calls. I do the same with fb2. Then i do some modification to the heaps. Lets say i do fb1.merge(fb2). Can i use the handles i obtained from the push calls on fb2 to update the data that was originally in fb2 and now in fb2?? That is the first time i obtain a handle_type from the push() method, it remains valid until the item is removed from the heap?? I tested the above scenario and seems to work but the documentation doesn't say anything and i would like another opinion. Thanks

1 0

Trying to extract sub library from Boost using BCP
by Colin Burn 16 Jan '14

16 Jan '14

I'm trying to extract "just what I need" from Boost to reduce the checkin footprint. So far I'm doing the following (On Windows): bootstrap.bat b2 tools/bcp md extract dist\bin\bcp boost/thread.hpp boost/shared_ptr.hpp boost/enable_shared_from_this.hpp boost/asio.hpp boost/thread/thread.hpp boost/bind.hpp boost/thread/lock_types.hpp boost/thread/condition_variable.hpp .\extract cd extract ..\b2but this gives me an error: boostcpp.jam: No such file or directory link.jam: No such file or directory Jamroot:137: in modules.load ERROR: rule "boostcpp.set-version" unknown in module "Jamfile<C:\temp\boost_1_55_0\extract>". C:/temp/boost_1_55_0/tools/build/v2/build\project.jam:311: in load-jamfile C:/temp/boost_1_55_0/tools/build/v2/build\project.jam:64: in load C:/temp/boost_1_55_0/tools/build/v2/build\project.jam:145: in project.find C:/temp/boost_1_55_0/tools/build/v2\build-system.jam:535: in load C:\temp\boost_1_55_0\tools\build\v2/kernel\modules.jam:289: in import C:\temp\boost_1_55_0\tools\build\v2/kernel/bootstrap.jam:139: in boost-build C:\temp\boost_1_55_0\boost-build.jam:17: in module scopeWhat am I doing wrong? What is the correct way to compile the extracted sub-library? Thanks Colin

1 0

[Geometry] Calculating the centre of a rectangle
by Sean Farrow 16 Jan '14

16 Jan '14

Hi All, I'm in the process of needing to calculate the centre point of a rectangle, given the top left and bottom right co-ordinates. Before I write this myself, I was wondering whether boost Geometry already has something to do this. Any help appreciated. Cheers Sean.

2 1

Re: [Boost-users] [Asio] signal_set not blocking/queueing signals on shutdown (Slava)
by Marat Abrarov 16 Jan '14

16 Jan '14

> >> I've written an io_service+signal_set signal handling implementation > >> in a thread of my application that triggers an orderly shutdown when > >> (among other things) the user presses Ctrl+C. > >> > > I first hear about asio signals, but I believe purpose of these signal > facility in asio is only to help you to implement *waiting* for signals, > like SIGCHLD, or SIGUSR{12}, whateverer you may choose for your IPC > communication. You should not misuse asio for general signal handling. > Normally signals are instantaneous things to be delivered right now right > here without any regard in which state the target is. I personally agree with Benjamin and think that the main goal of asio::signal_set is to provide the Asio way to handle signals. Look at the Asio examples (http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/examples/cpp03_exa mples.html) - the "HTTP Servers" series. They use asio::signal_set for the same goal/reason as Benjamin does. Regards, Marat Abrarov.

1 0

[Asio] signal_set not blocking/queueing signals on shutdown
by Benjamin Shadwick 16 Jan '14

16 Jan '14

I've written an io_service+signal_set signal handling implementation in a thread of my application that triggers an orderly shutdown when (among other things) the user presses Ctrl+C. According to the Boost.Asio documentation for signal_set ( http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio/reference/signal_s…) just having a signal_set (with inherent dependency on an io_service) with registered signals and not in a wait state is supposed to be enough to cause signals to be blocked/queued. After I stop the io_service and cancel the wait state on the signal_set, however, it appears that signal blocking/queueing is no longer occurring. I say this because hitting Ctrl+C during orderly shutdown after the io_service has stopped causes my application to instantly terminate (and in one case generate a core file). Is there something about stopping the io_service and/or canceling the async wait on the signal_set that is causing the note about signal queueing in the signal_set documentation to no longer apply? Thanks in advance.

2 2

[boost::shared_ptr] Easy to violate the One Definition Rule / C++11 / Check für standard used to compile Boost
by beet 15 Jan '14

15 Jan '14

Hi there, from what I can see, boost::shared_ptr has a different definition, depending on whether Boost is compiled in C++98 oder C++11 mode. For example, in C++11-mode, shared_ptr has a move-constructor. By default, however, Boost seems to be compiled in C++98 mode, even with a compiler like gcc 4.8 (Ubuntu 13.10 / 64 bit / Boost 1.55), that is perfectly capable of compiling in C++11 mode. So, while boost::shared_ptr is header-only, all Boost libraries that use boost::shared_ptr will assume the C++98 version. The build-environment of one of my applications checks the compiler (currently gcc and CLang) and, depending on the version, activates C++11 support, so that I can use some C++11-checks (such as override), that can easily be #defined away for C++98 . So what may happen here is that my main application uses a different boost::shared_ptr than the Boost libraries I want to link with. To me this seems to violate the one-definition rule (and may happen with other Boost libraries as well). Indeed I'm seeing some strange errors, where "if(!p) {raise_error();}" triggers for a shared_ptr<derived_class> p, but I can still access member functions of a base_class that derived_class is derived from. Now, while I'm not yet sure that the above is the cause of this problem, I'd like to make sure that my build system chooses the appropriate C++ standard for compilation. Hence: Is there any way I can check (e.g. through some #define provided by Boost) what C++ standard it has been compiled with ? Thanks and Best Regards, Beet

2 1

[Units] conversion between double and millimeter
by Richel Bilderbeek 15 Jan '14

15 Jan '14

Hello Boost.Units users, When I convert a double to a unit (e.g. meter) and back, this works as expected. When I convert a double to a prefixed unit (e.g. millimeter) and back, this fails to compile. The code below shows how I'd expect it to work. What do I overlook? Thanks, Richel Bilderbeek const double x_in_mm = 1.0; const Length x(x_in_mm * milli * meter); //This works as expected: const double x_again_in_m = x / meter; //Why doesn't this: const double x_again_in_mm = x / (milli * meter); //Fails

2 1

[log] Default logging configuration for trivial logger
by Ben Pope 14 Jan '14

14 Jan '14

Hi, I'm using the trivial logging interface, but I need to tweak the default configuration. I want to be able to flush after every log entry, and I also want to be able to do file rolling. As far as I can tell, in order to configure it this way, I pretty much need to configure the whole thing from scratch including formatters, but I can't find the code that sets up the default logger to replicate it. Any pointers? Cheers, Ben

1 0

boost.log: how to view open log files
by Georg.Kellerer＠lfu.bayern.de 14 Jan '14

14 Jan '14

Hi, currently i am writeng a windows service and use the boost.log library for logfile creation. The serive should run long and I want to view the log files when the service is running. At the moment the logfile is written to the disk when the service ends and the file always has a size of 0 bytes. Is there a way to configure boost.log in a way that the log entries are written to disk immideately and that the logfile is not locked for reading by another application so that I can view my logfile? Thanks a lot, Georg

3 3