- Boost-users - lists.boost.org

boost::thread_specific_ptr performance?
by Josef Grahn 16 Feb '07

16 Feb '07

Hi! What performance characteristics can be expected from a thread_specific_ptr on various platforms, as compared to other synchronizing primitives? Does accessing it cost the equivalent of locking a mutex, or is it generally faster than that? Specifically, would the cost of accessing it be noticeable if one were to use it (naively) to manage detailed per-thread logging, generating many thousands of access calls per second or more. Thanks in advance! Best regards, Josef Grahn

1 0

Re: [Boost-users] Help
by Sergey Ostrovskiy 16 Feb '07

16 Feb '07

"Peter Dimov" <pdimov(a)mmltd.net> wrote in message news:<005201c7515d$f2fbdff0$6607a8c0@pdimov2>... > Sergey Ostrovskiy wrote: > > > Now I want to write something more difficult: > > > > apReports.push_back(make_report(boost::lambda::bind(&CItem::GetItemCount)*boost::lambda::bind((&CItem::GetItemBytes))); > > boost::lambda::bind(&CItem::GetItemCount, _1) * > boost::lambda::bind((&CItem::GetItemBytes, _1) Unfortunately this code produces errors during the compiling: error C2678: binary '*' : no operator found which takes a left-hand operand of type 'const boost::lambda::lambda_functor<T>' (or there is no acceptable conversion)

1 0

[signals] Chaining slots
by Allan Douglas 16 Feb '07

16 Feb '07

Hello, I'm using Boost.Signals to implement Deferreds (http://twistedmatrix.com/projects/core/documentation/howto/defer.html) An important feature of Deferreds is the hability to chain callbacks. Speaking of Signals, I want a way to call slots using args from previous slots calls. For example: float square(float x) { return x*x; } float sum1(float x) { return x+1; } boost::signal<float (float x)> sig; /* do some magic here */ sig.connect(&square); sig.connect(&sum1); sig.connect(&square); // sig(2) should call square(sum1(square(2))) std::cout << sig(2) << std::endl; I want the example to output 25 ( (2**2)+1)**2) Any ideas on how to implement this? Thanks, Allan Douglas

3 4

[mem_fn] Using mem_fn with std::bind2nd
by Scott Meyers 16 Feb '07

16 Feb '07

The mem_fn documentation is clear that there may be problems using mem_fn with the standard binders: > mem_fn is not 100% compatible with the standard adaptors, although it comes pretty close. In particular, mem_fn does not return objects of type std::[const_]mem_fun[1][_ref]_t, as the standard adaptors do, and it is not possible to fully describe the type of the first argument using the standard argument_type and first_argument_type nested typedefs. Libraries that need adaptable function objects in order to function might not like mem_fn. Fair enough. The program below fails to compile with VC8 and g++ 4.1.1, and the VC8 error message (which I find much more readable than the g++ one) suggests that I'm running into the problem mentioned above. However, the program DOES compile using Comeau 4.3.8, and that's what confuses me. Does anybody have any insights into whether this code is supposed to compile? I'm especially interested in any remarks about whether it should compile using std::tr1::mem_fn, should there be any differences between that and boost::mem_fn. Thanks, Scott #include <vector> #include <algorithm> #include <functional> #include "boost/mem_fn.hpp" struct Point { void rotate(int degrees); }; int main() { std::vector<Point> vp; std::for_each(vp.begin(), vp.end(), std::bind2nd(boost::mem_fn(&Point::rotate), 10)); }

2 2

Boost: Regular Expression question/bug?
by Derrick Schommer 16 Feb '07

16 Feb '07

Hi, I'm trying to understand if a regular expression I've designed is working correctly. It seems that I can make the regular expression match work "off by one" character in certain circumstances. For instance: The pattern: ".{1,3}" finds 1 to 3 characters, however The pattern: ".[^b]{1,3}" finds 1 to 4 characters...? For some reason when I apply a "do not allow the character b" or any other bracket operator the {min,max} range value seems to allow for one additional character. I cannot imagine this being done on purpose. The work around is to allow one less then you really want (i.e. {1,2}) but I figured I'd post something and see if anyone has seen it or could explain what is happening. Maybe its just a bug. The code example: boost::wregex pattern( TEXT( ".{1,3}" ) ); boost::wcmatch matchResults; if( boost::regex_match( TEXT( "asd" ), matchResults, pattern ) ) { // Match } else { // No match } } catch( runtime_error &e ) { printf( "\n%%FAILURE: Regular expression error: %s.\n", e.what() ); } Yes, I'm running in a UTF-16 build environment in Microsoft Windows .NET using C++. If this isn't the correct venue for this message, sorry in advance. Thanks, Derrick

3 4

Re: [Boost-users] Help
by Sergey Ostrovskiy 15 Feb '07

15 Feb '07

"Peter Dimov" <pdimov(a)mmltd.net> wrote in message news:<008801c75115$0caf8120$6607a8c0@pdimov2>... Сергей Островский wrote: > I have a problem. Here is example of my code: > Now I want to output to a stream some fields of CAddress class. I can > get a reference to CAddress object with the CItem::GetAddress method. > So I am writing something like it: > > apReports.push_back(make_report(boost::bind(&CAddress::GetName,boost::mem_fun(&CItem::GetAddress))); > apReports.push_back(make_report(boost::bind(&CAddress::GetSize,boost::mem_fun(&CItem::GetAddress))); > > these 2 lines are not compiled. >Use > boost::bind( &CAddress::GetName, boost::bind( &CItem::GetAddress, _1 ) ) Peter, you are better! I think that should be simple solution. Thank you! Now I want to write something more difficult: apReports.push_back(make_report(boost::lambda::bind(&CItem::GetItemCount)*boost::lambda::bind((&CItem::GetItemBytes))); or apReports.push_back(make_report(boost::lambda::bind(&CItem::GetItemCount)*100.0/boost::lambda::bind((&CItem::GetTotalCount))); Is there any way to make it with boost library? _______________________________________________ Boost-users mailing list Boost-users(a)lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users ----------

2 1

[serialization] reliable storage / ACID transactions
by Pavlo Korzhyk 15 Feb '07

15 Feb '07

I have an (allmost) ready client-server system. The server maintains some sort of object-database that is saved to an xml file for persistence. Boost serialization is used for both persistance & networking. Is there any easy way to add some "mature" storage system? Something that will store different objects in different entities of the database would be ideal. Are there any ready solutions for RDBMS or Berkeley DB? -- WBR, Pavlo Korzhyk ICQ#155870780

1 0

boost::thread problems with Visual Studio SP1 & /clr
by John Dunn 15 Feb '07

15 Feb '07

A while ago I posted a problem to the list about issues I was having using the beta Visual Studio SP1, statically linking to boost::threads and compiling with /clr ( http://thread.gmane.org/gmane.comp.lib.boost.user/22464/focus=22617 ). SP1 has been recently released and the problem still exists. I resubmitted a bug report to Microsoft and they have marked the bug as [Won't Fix]. https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?Feedb… A workaround is to use the DLL version of boost::threads. This is not ideal, as I'd rather not have yet another DLL to cart around with my application. I'm guessing that supporting the /clr switch in boost isn't a high priority but it is the most straightforward way to integrate portable code ( communications, etc ) into a C# application. John

2 2

The test project looking for library v1.33 NOT v1.33.1 Why???
by fanz 15 Feb '07

15 Feb '07

I corrected the subject of email: From The test project looking for library v1.33.1 NOT v1.33. Why??? To The test project looking for library v1.33 NOT v1.33.1 Why??? -----Original Message----- From: fanz [mailto:fanzhe_cui@yahoo.com] Sent: Thursday, February 15, 2007 11:22 AM To: 'boost-users(a)lists.boost.org' Subject: The test project looking for library v1.33.1 NOT v1.33. Why??? I was trying to build Slexer that was in WAVE library that came with BOOST v1.33.1 pkg. I think this might be a configuration problem of boost version, but I could not figure it out, although I looked in every setting of VC++8.0 for the boost. When I build the slexer program with VC++8.0 I got the error: 1>------ Build started: Project: test, Configuration: Debug Win32 ------ 1>Linking... 1>LINK : fatal error LNK1104: cannot open file 'libboost_wave-vc80-mt-gd-1_33.lib' 1>Build log was saved at "file://c:\Users\Testing\tool_test\wave\test\testlexers\Debug\BuildLog.htm" 1>test - 1 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== But I did not designate the link library to 'libboost_wave-vc80-mt-gd-1_33.lib, and I don't know what setting made VC++8.0 looking for this lib. I want to VC++8.0 look for the library version v1.33.1 NOT v1.33. Does anybody have any ideas or comments? Thank you! Fanz

1 0

Help
by Сергей Островский 15 Feb '07

15 Feb '07

I have a problem. Here is example of my code: class CAddress { public: std::string GetName()const; int GetSize()const; }; class CItem { public: const CAddress& GetAddress()const; int GetItemCount()const; int GetItemBytes()const; }; class CReport { public: virtual ReportItem(const CItem& rItem,std::ostream& out)const = 0; }; template<class TFormula>class CReportFormula : public CReport { TFormula m_f; public: CReportFormula(TFomula f) : m_f(f){} virtual ReportItem(const CItem& rItem,std::ostream& out)const { out << m_f(rItem); } }; template class<TFormula> CReport* make_report(TFormula f) { return new CReportFormula<TFormula>(f); } somewhere in code: std::vector<CReport*> apReports; apReports.push_back(make_report(boost::mem_fun(&CItem::GetItemCount))); apReports.push_back(make_report(boost::mem_fun(&CItem::GetItemBytes))); it's Ok and it does work. Now I want to output to a stream some fields of CAddress class. I can get a reference to CAddress object with the CItem::GetAddress method. So I am writing something like it: apReports.push_back(make_report(boost::bind(&CAddress::GetName,boost::mem_fun(&CItem::GetAddress))); apReports.push_back(make_report(boost::bind(&CAddress::GetSize,boost::mem_fun(&CItem::GetAddress))); these 2 lines are not compiled. Where is my error? Can I resolve this problem with boost library? Now I fixed these problem with that code: template<TResult> class CReportAddress : public CReport { TResult (CAddress::*m_p)()const; public: CReportAddress( TResult (CAddress::*_p)()const) : m_p(p){} virtual ReportItem(const CItem& rItem,std::ostream& out)const { const CAddress& rAddress = rItem.GetAddress(); out << (rAddress.*m_p)(); } }; template<class TResult>CReport* make_report(TResult (CAddress::*p)()const) { return new CReportAddress<TResult>(p); } apReports.push_back(make_report(boost::mem_fun(&CAddress::GetName))); apReports.push_back(make_report(boost::mem_fun(&CAddress::GetSize))); but may be there is some better and more common solution?

3 2