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Moving property map library into a directory
by Jeremiah Willcock 08 Apr '09

08 Apr '09

The Boost Property Map Library (property_map) currently consists of a number of files in the top-level boost/ include directory. It would probably be better to move all of them into a subdirectory, especially as Nick Edmonds and I will be adding new files and directories into that library soon. Should I do that move? I will update Boost.Graph; are there other libraries in Boost that use property_map? -- Jeremiah Willcock

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Re: [boost] Compilation errors upgrading boost from 1.34 to 1.37 (Windows)
by tinkertom 08 Apr '09

08 Apr '09

I figured out what my problem was: When constructing a boost::mutex::scoped_lock in 1.33 the second parameter is a boolean. In 1.38, boost::mutex::scoped_lock (defined as unique_lock) constructor is overloaded using different types as the initial lock state instead of a single constructor with a boolean. In the constructor I now have to use adopt_lock_t, defer_lock_t, or try_to_lock_t as the second parameter. In 1.33: boost::mutex mtx; boost::mutex::scoped_lock lock(mtx, false); In 1.38 now looks like: boost::mutex mtx; boost::mutex::scoped_lock lock(mtx, defer_lock_t()); -Tom -- View this message in context: http://www.nabble.com/Compilation-errors-upgrading-boost-from-1.34-to-1.37-… Sent from the Boost - Dev mailing list archive at Nabble.com.

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Shorter link to getting started
by Vladimir Prus 08 Apr '09

08 Apr '09

I would like to modify the configure script to mention getting started, so that user knows where to look for information, but unfortunately, the current URL is a bit long: http://www.boost.org/doc/libs/1_38_0/more/getting_started/unix-variants.html It is 77 characters, so it does not leave any space for any other text. Can the website administrators arrange for some shorter redirect to be available? Say http://www.boost.org/getting_started/unix-variants.html ? Thanks, Volodya

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[data_binding] Lets bind data
by Kasra 08 Apr '09

08 Apr '09

Hi, I am looking for interest in data_binding techniques in C++. The idea is to have a class that could bind to a list of data and when ever any of them is changed the value of the binder is changed too: data_bindee<mpz_class> x; data_bindee<mpz_class> y; typedef tuple<mpz_class,mpz_class> my_bind_tuple_type; struct my_bind_pred_type { template<typename BinderT> void operator(BinderT& me, my_bind_tuple_typeT t) { me.x = get<0>(t); me.y = 2 * get<0>(t); } }; data_binder<struct { mpz_class x,y; }, my_bind_tuple_type, my_bind_pred_type> point(x, y); // when ever data of x and y is changed the value of point // is updated too. Any suggestions?? Kasra With Best Regards -- Kasra Nassiri

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Preliminary progress on Boost.Python py3k support
by Haoyu Bai 08 Apr '09

08 Apr '09

Hi, I did some preliminary work on BPL py3k support in these days. With Troy's help we have a py3k SVN tree in sandbox now, which is branched from trunk. I also tried to compile BPL with Python 3, and by following the error report of the compiler, I did some patch - now we have 14 .cpp files out of 28 in total can be compiled. The patch is committed, you can see it here: [2]. Please point me out if the code has something don't conform to Boost coding policy. There's also something interesting, maybe a bug I caught, for example: (Search the changeset to see details) 39 // XXX(bhy) Potentional memory leak here since PyObject_GetAttrString returns a new reference 40 // const char *mod = PyString_AsString(PyObject_GetAttrString( self_, const_cast<char*>("__module__"))); 41 PyObject *mod = PyObject_GetAttrString( self_, "__module__"); Also I found some potential problem with Py_ssize_t, I will take this as a chance to fix them. The biggest problem I see still is the "Text Vs. Data Instead Of Unicode Vs. 8-bit" in py3k. As we discussed and the suggestion by Niall [3], we have a clear solution for this and I will work towarding this. The other changes in py3k such as PyObject_HEAD change, int type removal and unbound method removal also affected Boost.Python's code, but they don't require logical change of BPL code and easy to handle. Hopefully in the end of this summer, we will have a Boost.Python library with Python 3 support! Thanks again for many people's help! References: [1] https://svn.boost.org/trac/boost/browser/sandbox-branches [2] https://svn.boost.org/trac/boost/changeset/52118 [3] “Nabble - Python - c++-sig - Some thoughts on py3k support,” http://www.nabble.com/Some-thoughts-on-py3k-support-td22564813.html. -- Haoyu Bai

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[interprocess] Assign to shared_lock from scoped_lock
by Chard 08 Apr '09

08 Apr '09

If I have (template args removed for brevity): shared_lock sh_lock(mutex); scoped_lock sc_lock(move(sh_lock), try_to_lock); // Try for exclusive if (sc_lock) { ... sh_lock = move(sc_lock); // Drop back to shared *** not available } Should that assignment operator be available? Currently I'm working around this with: sh_lock.swap(shared_lock(move(sc_lock))); [or, alternatively: sh_lock = move(shared_lock(move(sc_lock))); ]

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Re: [boost] [Any] Reference counting
by Michael Howell 08 Apr '09

08 Apr '09

Steven Watanabe <watanabesj(a)gmail.com> wrote: > Have you read http://www.gotw.ca/gotw/045.htm? I haven't read it, and have looked into atomic numbers, but couldn't find the "Boost Way" to do it (except perhaps poking around with shared_ptr innards). I wanted to use intrusive counts, since we have control over the object we are sharing. Thorsten Ottosen <thorsten.ottosen(a)dezide.com> wrote: >If you want to improve the performance of any, the thing to do is to add > a small buffer optimization such that all buildin types (or equally > small UDT) are created on the stack. I'll look into that. Mathias Gaunard <mathias.gaunard(a)ens-lyon.org> wrote: > Also, any is a value type. We do not want it to have reference > semantics. So you'd need to use COW. Actually, copy on write/implicit sharing is what I was proposing, if you had looked at the code. > Hence this is fairly useless, especially since we're getting move > semantics soon. "Soon" is relative. The trunk GCC may support it instantly (may already), but Debian Stable won't, nor will MSVC (both which will be used for a good while). Also, you usually copy the value when you store it, which may or may not involve writing. For example: #include <boost/any.hpp> using namespace boost; struct example { any variable; }; int main() { example object; example object2; any value = "I Love Boost!"; object.variable = value; object2.variable = value; return 0; } Thanks for replying, everyone. -- Michael Howell mhowell123(a)gmail.com

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"[gsoc] Thread scheduler support for boost" [Re: for vicente.botet]
by Indradip Ghosh 07 Apr '09

07 Apr '09

Hi Vicente, Sorry for having missed your question earlier on my intended GSOC proposal. I actually intended to design the fine-grained scheduler for threadpool class itself. My detailed application is listed here in the googlesites: http://sites.google.com/site/threadpoolschedulergsoc2009/ Please let me know if you have any questions/ comments regarding my proposal. Thanks and Regards, Indradip. > Message: 7 > Date: Mon, 30 Mar 2009 08:36:36 +0200 > From: "vicente.botet" <vicente.botet(a)wanadoo.fr> > Subject: Re: [boost] "[gsoc] Thread scheduler support for boost" > To: <boost(a)lists.boost.org> > Message-ID: <C1B76DB53B1544F9B2C5618DB7A708EF@viboes1> > Content-Type: text/plain; charset="iso-8859-1" > > Hi, > > I'm wondering this shouldn't be considered as an extension of the Boost.Thread library more that the Boost.ThreadPool library. The ThreadPool library can be improved once these extension are in place, but also other application or libraries using threads. > > Let me know if I'm missing someething? > > Best, > Vicente

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Performance measurement
by Govindan, Nandagopal (GE Healthcare) 07 Apr '09

07 Apr '09

Hi, I would like to know how performance measurement( time & memory ) done in boost. Do boost has some following APIs to measure performance?? Profiler.start() Code to be measured Profiler.stop() Printstatistics() Regards Nandagopal

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[gsoc] improving any and variant
by Mathias Gaunard 07 Apr '09

07 Apr '09

A few little ideas that could eventually be joined to be a single GSoC project: - Allow visitation for Any. This can actually be generalized to any object that exposes a type_info, such as polymorphic objects. Techniques, including non-portable ones based on name mangling, could be experimented to get more efficient dispatch. - Add SBO to any. - Improve variant so that the functor doesn't require to expose a result_type. The result_type can be automatically deduced by "joining" all the possible return types obtained by boost::result_of. - Allow the easy construction of a visitor from lambda expressions, with a syntax like variant<int, std::string> a = "foo"; int b = match(a).with( args<int>(_1), args<std::string>(size(_1)) ); instead of the potentially more verbose struct my_visitor : static_visitor<int> { int operator()(int a) { return a; } int operator()(const std::string& b) { return b.size(); } }; variant<int, std::string> a = "foo";; int b = apply_visitor(my_visitor(), a);

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