November 2010 - Boost-users

get/set RTS on serial port - Linux
by Marce 05 Nov '10

05 Nov '10

Hi, In a later post of myself I asked about getting / setting the RTS line by software control (http://lists.boost.org/boost-users/2010/06/59700.php) I managed to get working as explained in Windows as replied in by Michael Caisse (http://lists.boost.org/boost-users/2010/06/59723.php) but in linux I'm not being able to get it working. I can control it in linux by calling ioctl ( ioctl(fd, TIOCMSET, &status) ) but in the set-option I do not have the file descriptor but the termios that I don't completely understand. Does someone provide me and example to make this 'option' This is my RTSControl option class: class RTSControl { public: explicit RTSControl(bool enable = false) : m_enable(enable) {}; boost::system::error_code store(BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) const { #if defined(BOOST_WINDOWS) || defined(__CYGWIN__) if (m_enable) storage.fRtsControl = RTS_CONTROL_ENABLE; else storage.fRtsControl = RTS_CONTROL_DISABLE; #else #endif return ec; }; boost::system::error_code load(const BOOST_ASIO_OPTION_STORAGE& storage, boost::system::error_code& ec) { #if defined(BOOST_WINDOWS) || defined(__CYGWIN__) if (storage.fRtsControl == RTS_CONTROL_ENABLE) m_enable = true; else m_enable = true; #else #endif return ec; }; private: bool m_enable; }; BOOST_ASIO_OPTION_STORAGE is termios for Linux systems.

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[Proto] lambda functions with named variables
by Hossein Haeri 04 Nov '10

04 Nov '10

Dear all, I am thinking of having creatures like lam(x)(x + 2) in my code which would be the Haskell equivalent for \x -> x + 2. In fact, I am working in an untyped world (with very limited functionality) and my typical lambda expressions would only include (function) applications, (lambda) abstractions, and let-bindings. It is exactly for the existence of let-bindings that I guess I can't resort to placeholders like: template<int> placeholder; const terminal<placeholder<0> >::type _1 = {{}}; const terminal<placeholder<1> >::type _2 = {{}}; const terminal<placeholder<2> >::type _3 = {{}}; ... The point is that I need to store what each variable is bound to. And, AFAIK, I can't store such information in std::map<> for _1 has a different type than _2 for example. So, the two hopes that I have in Proto for solving this problem are: 1) To provide a type T instances of which can act like untyped variables in accepting values of different C++ types. T should also be storable in a map-like container. Boost.Any comes to mind for the first requirement but the problem is that there is no meaningful operator < or operator == to use map or unordered_map for boost::any objects. Note that a1 != a2 needs to the case only when a1 and a2 are distinct variables. Can proto::_ be of any help here? 2) To provide a map-like container in which I can store things like boost::any objects. OK, maybe this is not for Proto to address but though it might still have something to offer... TIA, --Hossein

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[proto]: Adding functions to the lazy vector example
by Noman 04 Nov '10

04 Nov '10

Hi I am experimenting with the lazy vector example. I want to add the functions to the example but not in the LazyVector class. Like for example I want to add a function INC which increments each element of the vector and returns a vector. How can I add this to the example? Thanks in anticipation Regards

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bjam in 1.44 vs 1.39
by Jonathan Brannan 04 Nov '10

04 Nov '10

We recently switched from boost 1.39 to boost 1.44. We use the bjam and boost build packaged with the version of boost we use. It seems that the bjam packaged with 1.44 exists with 0 even if there is a failure: ...failed gcc.compile.c++ /home/foo/Foo.o... ...failed updating 1 target... machine:/home/foo # echo $? 0 It stops early with the -q and prints out that it failed, it just exits 0. bjam -v Boost.Jam Version 3.1.18. OS=LINUX. Copyright 1993-2002 Christopher Seiwald and Perforce Software, Inc. Copyright 2001 David Turner. Copyright 2001-2004 David Abrahams. Copyright 2002-2008 Rene Rivera. Copyright 2003-2008 Vladimir Prus. With Version 3.1.17. OS=LINUX version that came with 1.39, I get an exit status of 1, which is what I expect.

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[mpl] Iterator Concept Checking?
by Stirling Westrup 04 Nov '10

04 Nov '10

I am writing some algorithms to operate on MPL sequences, and I would like to use some form of concept checking to ensure that the types passed in that are supposed to be iterators are, in fact, iterators. The MPL library doesn't seem to have is_XXX_iterator<T> checks, and I have run into some difficulties in determining how to write them. The MPL documents state that a random_access_iterator is a 'refinement' of a bidirectional_iterator which is a 'refinement' of a forward_iterator, but its not clear what refinement means in this context. I initially assumed that this meant that a random_access_iterator_tag was derived from a bidirectional_iterator_tag which was derived from a forward_iterator_tag. This does not appear to be the case, so the obvious test for an iterator (checking that the class contains a member named 'category' that is a type derived from the iterator tag of the least acceptable iterator) will not work. I am sure I could cobble together something that would work by examining the internals of the library, but I would far rather have some guidance on the correct way to see if an iterator matches a given iterator model, within the API of the library. Does anyone have any suggestions? -- Stirling Westrup Programmer, Entrepreneur. https://www.linkedin.com/e/fpf/77228 http://www.linkedin.com/in/swestrup http://technaut.livejournal.com

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boost::recursive_mutex doesn't lock ???
by Chris 03 Nov '10

03 Nov '10

Hello. I have a question about mutexes: Scenario 1: (OK) int main() { boost::mutex io_mutex; io_mutex.lock(); // thread will be blocked now boost::mutex::scoped_lock lock(io_mutex); cout << "Test" // this statement is not executed: OK } So far no problem, but if I use recursive_mutex instead... Scenario 2: (NOT OK) int main() { boost::recursive_mutex io_mutex; io_mutex.lock(); // thread will NOT be blocked ??? boost::recursive_mutex::scoped_lock lock(io_mutex); cout << "Test" // this statement is executed ??? } no blocking occurs?? I tried with unique_lock instead of scoped_lock but still no blocking Why not? I don't understand. How does one lock a recursive_mutex then? thank you Chris

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[Any] Operator ==
by Hossein Haeri 03 Nov '10

03 Nov '10

Dear all, Is there any way to implement an operator == (and perhaps also operator !=) for objects of type boost::any so that different instances are always != and an instance is always only == to itself -- regardless of the respective values? In case you're wondering why I'd interested in such operators, the answer is that I'm thinking of storing objects of type boost::any in an unordered_map. So, it would be equivalently helpful if you could provide a function object to be sent as the Pred template parameter to boost::unordered_map. TIA, --Hossein

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[asio] Removing server socket from service
by Sakharuk, Vladimir 03 Nov '10

03 Nov '10

I have one thread how runs io_service. I have 2 servers (tcp) ports with all corresponded acceptor and bunch of sockets connected to both ports. I am looking into the way to stop just one server but still run the other one. I have implemented a "hard" way to stop server: remove acceptor, cancel/close sockets, that will trigger all read/write asynchronous callbacks, wait till they all done. but there is a incontinence I need to know how may callbacks still here. Is there any simpler way to do the same thing? Something like block the cancel call until all call back done? Please follow the attached hyperlink to an important disclosure: http://www.credit-suisse.com/legal/marketcommentary =============================================================================== Please access the attached hyperlink for an important electronic communications disclaimer: http://www.credit-suisse.com/legal/en/disclaimer_email_ib.html ===============================================================================

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[range] multiple adaptors on sequense
by Sam Fisher 03 Nov '10

03 Nov '10

Hello, Is it possible to apply multiple adaptors to a range-base sequence? Is looks like possible for simple types: #include <string> #include <vector> #include <boost/shared_ptr.hpp> #include <boost/make_shared.hpp> #include <boost/range/algorithm_ext/push_back.hpp> #include <boost/range/adaptor/uniqued.hpp> #include <boost/range/adaptor/transformed.hpp> #include <boost/assign.hpp> using boost::assign::operator +=; #include <boost/spirit/home/phoenix.hpp> namespace phx = boost::phoenix; int square(int val) { return val * val; } int range_test_simple() { typedef std::vector<int> V; V source; source += 1,1,1,2,2,2,3,3,3,4; using namespace boost::adaptors; V result; boost::push_back(result, source | transformed(&square)); // Ok boost::push_back(result, source | uniqued); // Ok boost::push_back(result, source | transformed(&square) | uniqued); // Ok boost::push_back(result, source | uniqued | transformed(&square)); // Ok return 0; } but how about this? (source is continued...) struct Foo { Foo(const std::string& name, int value) : name_(name), value_(value) { } std::string name_; int value_; }; typedef boost::shared_ptr<Foo> FooPtr; int range_test_complex() { typedef std::vector<FooPtr> V; V source; source += boost::make_shared<Foo>("Foo", 10), boost::make_shared<Foo>("Bar", 20), boost::make_shared<Foo>("Baz", 30), boost::make_shared<Foo>("Baz", 30) // duplicate is here ; std::vector<std::string> result1; std::vector<int> result2; using namespace boost::adaptors; using phx::arg_names::arg1; boost::push_back(result1, source | transformed(phx::bind(&Foo::name_, *arg1)) | uniqued); // Fails boost::push_back(result2, source | transformed(phx::bind(&Foo::value_, *arg1)) | uniqued); // Fails return 0; } What I'm doing wrong? I use MSVS 2010 and boost trunk. Thanks, Sam

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Managing pipelines?
by Olivier Tournaire 03 Nov '10

03 Nov '10

Hi all, I am currently thinking on how to handle pipelines in some of my application. By pipeline, I mean "something" in which I can set an input, add some processing on that input, and retrieve the output (the result of the processing). If I am not clear enough, let's go with an example. Suppose I have an image, and I want first to crop it, then apply a filter on the crop and get the result in another image. Does boost has a library with such a feature? Best regards, Olivier ----------------------------------------------------- Olivier Tournaire MATIS - Institut Géographique National 73, Ave de Paris 94165 St Mandé cedex, France tel: (+33) 1 43 98 84 29 fax: (+33) 1 43 98 85 81

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