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

Re: [Boost-users] Boost-users Digest, Vol 1586, Issue 4
by Jeff 30 Mar '08

30 Mar '08

Hello everyone, Does the new MPI Library use ASIO? Thanks, Jeff

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A toolset for PSP
by Bruno Lalande 29 Mar '08

29 Mar '08

Hello, Maybe this can interest somebody here. I have written a toolset to compile Boost libraries for the Sony PSP console using the unofficial SDK provided by the PS2DEV team (http://ps2dev.org) based on GCC. The toolset is itself based on the Boost's original GCC toolset. I've opened a project on SourceForge (http://boost4psp.sourceforge.net) where you can download this toolset (package boost4psp-toolset) as well as some binaries compiled for PSP (package boost4psp). Binaries provided for now are Boost.Graph, Boost.Signals and Boost.Test (my personal need was originally to use Boost.Signals on PSP). I will add some more libraries from time to time (for those that are not platform-specific, obviously). Regards Bruno

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[boost.thread] Porting Windows event to boost::condition
by Raider 29 Mar '08

29 Mar '08

I'm porting WinAPI code to boost.thread. Confused converting Windows event to boost::condition... There are two threads, one waiting to another: HANDLE Event; // shared Event = CreateEvent(NULL, TRUE, FALSE, NULL); ... void Thread1() { ResetEvent(Event); MyCode::CreateThread2(); if (WaitForSingleObject(Event, 500 /*ms*/) != WAIT_OBJECT_0) ... } void Thread2() { SetEvent(Event); } My solution looks like this: boost::condition Condition; ... void Thread1() { MyCode::CreateThread2(); boost::mutex m; boost::mutex::scoped_lock l(m); if (!Condition.timed_wait(l, make500msdelay())) ... } void Thread2() { Condition.notify_all(); } Am I using boost::condition right way? Is `m' mutex nessesary? -- Raider

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Passed by Reference/Value?
by Venkatraman S 29 Mar '08

29 Mar '08

Hi, How are the C++ and Python objects maintained when the context switch happens between the two - i.,e in the following example, once i create an object of Var in Python and pass it to C++ - does it pass by reference or value? The reason why i am asking is this because , we are developing a highly 'memory optimized' application and need very judicious use of the memory - and hence expect it to happen via reference. I tried to use Valgrind package and look at the dumps , but was flummoxed by the dumps - couldnt comprehend it :) Regards, -- Venkat Blog @ http://blizzardzblogs.blogspot.com

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Python/C PyRun_String
by Venkatraman S 29 Mar '08

29 Mar '08

Hi All, Am using Pythong/C API for embedding. I have written a small-simple wrapper that does the low level functions and exposes the functionalities in a c++ style(i.,e the application layer doensnt use 'PyObject'). I am reading the contents of a file(Python script) and am running the same using PyRun_String; the script setups some variables in the Main Dict which i access it using the PyArg_Parse...etc etc(the standard way). This keeps running in a loop - i.,e it needs to be processed for every transaction - hence the Python wrapper is a singleton which preserves the main dict. Am stumbling on a problem wherein when i try to access a variable in Python from C as a string - this variable in python was constructed by concatenating a float with a string(using 'str'), and hence the resulting python variable is also a string. If i comment out the variable , then the program runs fine; else it(C program) throws out a segmentation fault. A clueless as to how to debug this and suitable hints would be immense help. (If required , i can share the code for this - i just didnt want to send it here) Secondly, can anyone point me to the Boost::python way of embedding - basically, i would like to know how to build/compile the program without using bjam. Regards, -- Venkat Blog @ http://blizzardzblogs.blogspot.com

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boost.program_options or boost bjam build issue
by Dan Pieczynski 28 Mar '08

28 Mar '08

I had rebuilt my library using bjam because I needed a 32 bit Linux build(while on a 64 bit machine). I built the libraries and linked them into my project. I was attempting to use my local boost files, but I get an error referring to another boost include directory which is a different version. I don't specify the path being referred to in my link steps anywhere, so I'm assuming my build with bjam didn't specify a necessary define. The error I see is: main.o(.gnu.linkonce.t._ZN5boost15program_options25basic_command_line_parserIcEC1EiPPc+0x53): In function `boost::program_options::basic_command_line_parser<char>::basic_command_line_parser(int, char**)': /usr/include/boost/program_options/detail/parsers.hpp:42: undefined reference to `boost::program_options::common_command_line_parser::common_command_line_parser(std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)' Where it refers to /usr/include/boost/program_options/detail/parsers.hpp while my intent was to use BOOST_ROOT=/home/dpieczynski/opt/libs/BOOST/boost_1_34_1/lib32 To build the library I defined BOOST_ROOT, then ran "./configure -prefix=lib32 -includedir=/home/dpieczynski/opt/libs/BOOST/boost_1_34_1" The library was then built with: bjam cxxflags=-m32 linkflags=-m32 cflags=-m32 architecture=x86 address-model=32 -d2 link=shared --prefix=lib32 threading=multi debug install -a What needs to be done to prevent the reference to /usr/include/boost? Thanks for your time and help. Dan Pieczynski _______________________________________________________ The information in this email or in any file attached hereto is intended only for the personal and confiden- tial use of the individual or entity to which it is addressed and may contain information that is propri- etary and confidential. If you are not the intended recipient of this message you are hereby notified that any review, dissemination, distribution or copying of this message is strictly prohibited. This communica- tion is for information purposes only and should not be regarded as an offer to sell or as a solicitation of an offer to buy any financial product. Email trans- mission cannot be guaranteed to be secure or error- free. P6070214

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variant comparison operators
by Jiri Palecek 28 Mar '08

28 Mar '08

Hello, is there some deep reason why comparing variant to a nonvariant is disabled? For example: variant<int, string> v=1; assert(v==1); // doesn't compile The problem is that there are overloads for anything else than a variant, which explicitely fail to compile (via static_assert and other means). If they weren't there, everything would work (the comparison would invoke conversion constructor, and then normal variant/variant comparison. Another problem is that variant includes the == operator, but not !=, even though this could be easily achieved with boost::operators. I can send patches if that would help. Regards Jiri Palecek

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Asio deadline_timer does not work when io_service::run is called from a Python thread.
by Eric Newhuis 28 Mar '08

28 Mar '08

Dr. Egon Spengler: There's something very important I forgot to tell you. Dr. Peter Venkman: What? Dr. Egon Spengler: Don't cross the streams. Apparently my deadline_timers don't work when I call io_service::run from python on Linux. Has anyone encountered this and worked around the problem?

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Re: [Boost-users] nondynamic: A utility class that promotes safe programming
by Daniel Lidström 28 Mar '08

28 Mar '08

Ovanes wrote: [snip] > What do you think how this allocator will allocate the number > of these element? Actually in any possible way. > It can use new[] or new char[sizeof(T)*NumElems] or use an > own mem-manager. And the worse thing you can't make > allocator friend of your class, since users of containers can > pass their own allocators. > And despite all enumerated facts you will fail to compile, > since the function address will fail to return the pointer to > x, because it is prohibited in your case. Yes, well boost::noncopyable also prohibits something :-) The whole intent of nondynamic is to prohibit (or make difficult) dynamic allocation/pointer usage. Do you think boost::noncopyable has a valid purpose, but nondynamic is less useful? -- Daniel

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Re: [Boost-users] nondynamic: A utility class that promotes safe programming
by Daniel Lidström 28 Mar '08

28 Mar '08

Hello Ovanes, Ovanes wrote: > Hello Daniel, > > I thought about such a class as well. The main disadvantage of it > is that it is impossible to use with standard containers. :( > Standard containers (e.g. std::vector) pre-allocate space for > some number of instances and use the placement new operator to > place items in the pre-allocated memory and when deriving form > nondynamic makes it impossible. As I understand it, the standard containers use the global placement new, which cannot be overridden. These lines are actually ok to do it seems: char dataIOBuffer[sizeof(DataIO)] = {0}; DataIO* inplaceCreated = ::new(dataIOBuffer)DataIO(IDataIOPtr()); Regardless of where I place (no pun intended) the placement new operator in nondynamic. -- Daniel

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