August 2006 - Boost - lists.preview.boost.org

Re: [boost] [intrusive_ptr] adding thread safety
by Dave Compton 02 Aug '06

02 Aug '06

> JOAQUIN LOPEZ MU?Z wrote: > > Hello, > > > > A naive usage of intrusive_ptr involves having a > > refcount embedded in the pointed to object and > > providing add_red and release functions like: > > > > void intrusive_ptr_add_ref(const my_class* p) > > { > > ++(p->ref); > > } > > > > template<typename T> > > void intrusive_ptr_release(const my_class* p) > > { > > if(--(p->ref)==0){ > > // whatever > > } > > } > > > > But, AFAICS, this is not thread safe, as intrusive_ptr > > itself does not add any thread safety layer. So my > > question is how to efficiently provide add_ref and release > > functions which are thread safe (wrt to refcounting)? I can > > use a class-level boost::detail::lightweight_mutex in the > > obvious way, but I understand shared_ptr uses much more > > advanced mechanisms and maybe these are available for > > (semi)public consuption at boost/detail. > > An atomic counter should suffice. boost::detail::atomic_count. Is it enough to use an atomic counter? It seems like the entire decrement *and test* operation in intrusive_ptr_release needs to be atomic. Otherwise you run the risk of the "// whatever" code being executed twice in different threads. Sorry for responding to a topic that is a little dated. I ran across this thread yesterday when I was dealing with the same issue.

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is_nan
by Joe Gottman 02 Aug '06

02 Aug '06

Several libraries have an is_nan() function buried deep in the code. Are there any plans to make a general is_nan function available? This would be quite useful, as well as similar functions like is_finite. Joe Gottman

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Re: [boost] Numerical integration library?
by Sohail Somani 02 Aug '06

02 Aug '06

> -----Original Message----- > From: boost-bounces(a)lists.boost.org > [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock > Sent: Tuesday, August 01, 2006 10:36 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] Numerical integration library? > > Sohail Somani wrote: > > Yes this is what I meant. It seems that there is different > > nomenclature regarding this relatively common concept. > > > > Is that your library you pointed to above? > > Yep, still work in progress as you can see. > > BTW, I'm also interested in numeric integration, but only of > the "integrate > function f from x to y" not ODE solving. Sigh, that > nomenclature again :-/ If I can only suggest: Decouple evaluation of the objective function from its derivatives. Or have another concept that is not callable. I have an example of how one can specify a family of functions and their derivatives: http://sohail.taggedtype.net/software/newton_raphson.cxx You can blame the idle hands for this one. Sohail

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numeric::interval::abs() bug
by Terry Golubiewski 02 Aug '06

02 Aug '06

The following code does not compile with g++ nor MSVC 2003 because of ambiguity of first argument to std::max() in numeric::abs(). Is a typecast needed in interval/utility.hpp? terry #include <boost/numeric/interval.hpp> #include <iostream> typedef boost::numeric::interval<short> Interval; std::ostream& operator<<(std::ostream& os, const Interval& x) { return os << x.lower() << ".." << x.upper(); } int main() { Interval r1(-3, 7); std::cout << "r1=" << r1 << std::endl; Interval r2 = boost::numeric::abs(r1); std::cout << "r2=" << r2 << std::endl; return 0; } // main

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bind/lambda/phoenix and result_of
by David Abrahams 02 Aug '06

02 Aug '06

One happy day, we'll have auto and decltype... Until then, we have no reasonable way to declare the type of bind expressions. So I got to thinking, maybe something like this could be made to work: result_of<bind_(std::minus<int>, int, _1_)>::type f = bind(std::minus<int>(), 3, _1); For lambda, I guess we could do something like this: result_of<minus_(int, _1_)>::type f = 3 - _1; Does this direction make sense? -- Dave Abrahams Boost Consulting www.boost-consulting.com

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Re: [boost] Boost.Operators base class chaining
by Steven Watanabe 02 Aug '06

02 Aug '06

AMDG Daniel, >> The only case I can think of that won't work is the unnumbered forms of >> binary operators. > > > Can you provide an example? > Regards, Daniel Sure. template<class Base> struct X : boost::addable<X, Base> { ... }; Boost.Operators does not recognize Base. Therefore, (as I understand the library) it will think I mean boost::addable2<X, Base> instead of boost::addable1<X, Base> In Christ, Steven Watanabe

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Getting a xsd:datetime from boost::date_time
by Joe Van Dyk 02 Aug '06

02 Aug '06

Hi, (sorry if this is off topic) I need to get the current date and time and convert it into a string that follows the xsd:datetime time stamp format: [-]CCYY-MM-DDThh:mm:ss[Z|(+|-)hh:mm]. (timezone should be UTC) Any ideas on how to do that? The Boost::Date_Time library documentation is confusing to my feeble mind. Thanks, Joe

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[Boost-bugs] [ boost-Support Requests-1532704 ] boost version 10/2002
by SourceForge.net 01 Aug '06

01 Aug '06

Support Requests item #1532704, was opened at 2006-08-01 13:41 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1532704&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: boost version 10/2002 Initial Comment: I've been put on a project that used boost version 10/2002 previously. I need to get that version. How and where can i do so? thank you for your help! Greg gmolnar(a)blackbirdtech.com ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1532704&group_… ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1532684 ] Changing size of memory-mapped file on Windows
by SourceForge.net 01 Aug '06

01 Aug '06

Bugs item #1532684, was opened at 2006-08-01 13:10 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1532684&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: Changing size of memory-mapped file on Windows Initial Comment: My email address is barrywhart(a)yahoo.com. There is a bug in mapped_file_source::open_impl(mapped_file_params p) This function does not correctly check for errors from SetFilePointer, as documented in the MSDN page below. (See "Case Two: calling the function with lpDistanceToMoveHigh != NULL") http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/fs/… Current code: ::SetFilePointer(pimpl_->handle_, sizelow, &sizehigh, FILE_BEGIN); if (::GetLastError() != NO_ERROR || !::SetEndOfFile(pimpl_->handle_)) detail::cleanup_and_throw(*pimpl_, "failed setting file size"); Should be: DWORD dwResult = ::SetFilePointer(pimpl_->handle_, sizelow, &sizehigh, FILE_BEGIN); if (dwResult == INVALID_SET_FILE_POINTER ::GetLastError() != NO_ERROR || !::SetEndOfFile(pimpl_->handle_)) detail::cleanup_and_throw(*pimpl_, "failed setting file size"); -- Even after this fix, the ability to resize an existing file is not really useful because the file is apparently recreated rather than resized. I am working around this by resizing the file using system calls, but I wonder if this is how the function is supposed to work?! ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1532684&group_… ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Re: [boost] Boost.Operators base class chaining
by Steven Watanabe 01 Aug '06

01 Aug '06

AMDG > Are you familiar with Alexander Nasonov's dynamic_any? No I hadn't seen it. Thanks for pointing it out. In Christ, Steven Watanabe

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