- Boost-users - lists.boost.org

Re: [Boost-users] how to use shared_ptr to wrap std::vector and returnfrom function?
by Sohail Somani 21 Mar '06

21 Mar '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org > [mailto:boost-users-bounces@lists.boost.org] On Behalf Of > kdsfinger(a)gmail.com > Sent: Monday, March 20, 2006 9:59 AM > To: Boost-users(a)lists.boost.org > Subject: [Boost-users] how to use shared_ptr to wrap > std::vector and returnfrom function? > > hi, Boost users > > Suppose I created a large data in a function and want to > return it back to where the function was called. I want to > return the pointer so that the deep copy of the large data is > not needed and memory leak is nicely handled. Can someone let > me know how to do it? This is what auto_ptr is for, shared_ptr is overkill as far as I can tell: #include <iostream> #include <memory> #include <vector> typedef std::auto_ptr<std::vector<double> > avd; avd getV() { avd a(new std::vector<double>); a->reserve(2); a->push_back(1.0); a->push_back(2.0); return a; } int main() { const avd a = getV(); std::vector<double> & ref = *a; std::cout << ref[0] << " " << ref[1] << std::endl; ref[0]=5; std::cout << ref[0] << " " << ref[1] << std::endl; }

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[regex] Working with wchar_t on older UNIX platforms
by Andrei Tarassov 21 Mar '06

21 Mar '06

Hi! I am experiencing a problem with integrating boost::regex into one of software projects. The problem is that the project supports a number of old operating systems (such as AIX 4.3.3 and HP-UX 11.00), where full support for functions working with wide characters (wchar_t) does not exist. This causes GCC to be compiled without wstring support. On the other hand, we do use wchar_t to the extent allowed by these operating systems and find the limited support more or less enough. Now I tried to integrate wregex in the software, but it just would not compile complaining about missing wstring (and defined BOOST_NO_WREGEX). I tried to make up my own regex character traits class, but this does not seem to help, because some other classes/types (such as sub_match) make use of basic_string<charT>. Is there any way to bypass the problem? I could be using the plain-char version of regex, but that causes me problems with determining the position of a match in the original wide-character string (conversion from wchar_t to char could involve some multibyte encoding). Thanks, -- ANDREI TARASSOV Software Engineer III Altiris OÜ T > +372 6507154 M > +372 53403298 www.altiris.com Security. Compliance. Patch management. IT service management. Altiris solves your most pressing IT issues. www.altiris.com

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Boost.regex examples using boost::mapfile::iterator and std::string::const_iterator
by John Grabner 21 Mar '06

21 Mar '06

I used the regex library from version 1.28.0 with BCB6. I was able to have a single function CommentsStrings::MatchFound(boost::match_result<std::string::const_iterator> what); to process both a std::string and a boost::mapfile. The calling functions are: //--------------------------------------------------------------------------- void CommentsStrings::Analyse(const std::string& Buffer) { Buffer_ = Buffer; AllCommentsStrings_.clear(); // find comments and strings std::string::const_iterator start, end; start = Buffer_.begin(); end = Buffer_.end(); boost::regex_grep( std::bind1st(std::mem_fun(&CommentsStrings::MatchFound), this), start, end, CommentStringExpression); } //--------------------------------------------------------------------------- void CommentsStrings::Analyse(const char *file) { currentFile = file; AllCommentsStrings_.clear(); // find comments and strings boost::mapfile f(currentFile.c_str()); boost::mapfile::iterator start, end; start = f.begin(); end = f.end(); boost::regex_grep( std::bind1st(std::mem_fun(&CommentsStrings::MatchFound), this), start, end, CommentStringExpression); } Now I am using BDS2006 and boost 1_33_1 I am getting an error Could not find a match for 'std::bind1st<std::mem_fun_t<bool,CommentsStrings,smatch> >::operator ()(cmatch)'. I know that the iterator for std::string is a class and not a char pointer. I am at a loss as how to proceed. John.

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boost/thread/once.hpp - problem with boost::call_once() on MSVC++ on AMD64
by Bill Somerville 21 Mar '06

21 Mar '06

Hi I'm having trouble linking a program that uses boost::call_once() on a Windows AMD64 machine. I get a link error saying _InterlockedCompareExchange() is undefined - this should be an intrinsic function on this platform but I think the code in thread/src/once.cpp where the address is taken of the intrinsic function has fooled the development system. It works OK on IA64 were the function is also intrinsic. We are building statically so it's possible that we are not passing some compiler switch that fixes this - but I don't see it. Has anyone else hit this problem with 64-bit AMD64 code and boost::call_once() on Windows? Compiler version is: Microsoft (R) C/C++ Optimizing Compiler Version 14.00.40121 for AMD64 Bill Somerville

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2D multiindex container or simply vector<vector<T> > ?
by Sliwa, Przemyslaw (London) 21 Mar '06

21 Mar '06

What is better? What is the added value by using 2D multi index container vs. vector<vector<T> >? Can anyone explain me the difference quickly? Thanks for help Pshemek Kind regards Pshemek Przemyslaw Sliwa Global Foreign Exchange FX Risk Engine Development Merrill Lynch ( +44 (0)20 7995 4182 ) +44 (0)79 6325 2319 * Email: przemyslaw_sliwa(a)ml.com -------------------------------------------------------- If you are not an intended recipient of this e-mail, please notify the sender, delete it and do not read, act upon, print, disclose, copy, retain or redistribute it. Click here for important additional terms relating to this e-mail. http://www.ml.com/email_terms/ --------------------------------------------------------

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Thank you !! - Joaquin & all
by Aashit Soni 21 Mar '06

21 Mar '06

Hi Joaquin, If you remember i had few questions sometime back on multi-index-container. You helped me figure it out. Last week i was able to squeeze 70%- 80% more performance with the new implementation of my storage classes, with the help of hash_index and ordered_index. This is tremendous result and i owe it to you. !!! Thank you very much for such wonderful data-structure. I appreciate all your help, that you have extended. This is first performance result, which is like a tip of an iceberg. I have still more rounds of scenerios to test upon. But this kind of results is really encouraging and i am sure now i will able to take it up forward. I am worried with the licensing issues and support provided for the boost library. If anyone can point me out in that direction. Once again thanks to Joagin and all on the list. regards, aashit

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Re: [Boost-users] enable_shared_from_this - or an alternative..
by Nat Goodspeed 21 Mar '06

21 Mar '06

> -----Original Message----- > From: boost-users-bounces(a)lists.boost.org [mailto:boost-users- > bounces(a)lists.boost.org] On Behalf Of James Hughes > Sent: Monday, March 20, 2006 11:29 AM > To: 'boost-users(a)lists.boost.org' > Subject: Re: [Boost-users] enable_shared_from_this - or an alternative.. > > > >I have a couple of classes that I want to self register > > themselves with a > > >monitoring class. To do this they must pass a shared_ptr of > > themselves to > > >the monitor register function. > > > > > >Therefore I need to make a shared_ptr form the this pointer, in the > > >constructor. [Nat] We have a similar need: the base class registers in a central registry; we have many subclasses of the base class. We use dumb base* pointers for this purpose. We can get away with that because, just as the base-class constructor registers each instance, so the base-class virtual destructor unregisters the instance. Indeed, for our purposes, we don't WANT smart pointers in the registry. If the last smart-pointer reference to a heap object goes away, we don't want the reference in the registry to make the instance immortal. In that case, the smart pointer to the heap object decrements the count to 0, the object is destroyed, and its destructor unregisters the instance. A side benefit is that we don't have to care whether the instance is static, auto or heap. Nor do we need factory functions.

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Support for Thread lib on MinGW?
by Matt England 20 Mar '06

20 Mar '06

Will Boost ever support the Thread library for mingw? As per http://boost.org/more/getting_started.html#auto-link : " <libthread>: For technical reasons static linking is supported on only one Windows compiler (Visual C++). " -Matt

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System call to get current process memory usage?
by Matt England 20 Mar '06

20 Mar '06

What if any system calls exist to get the current process' system memory usage (including all of the current process' threads)? I'm trying to write unit tests to make sure that my memory allocation processes (for Boost "smart pointers) are actually deallocating correctly after thousands of dynamic allocations...and my presumption is that a process-memory "self check" thoughout this process will be very useful for my self-running unit test. I'd prefer cross-platform calls (be it POSIX, unix/linux, Boost C++, etc...preferably not win32-specific if I can avoid it, but if I must I will) if I can get them, but I'll take a system specific all (for my testing prototype) if I must. Thanks for any help, -Matt

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how to use shared_ptr to wrap std::vector and return from function?
by kdsfinger＠gmail.com 20 Mar '06

20 Mar '06

hi, Boost users Suppose I created a large data in a function and want to return it back to where the function was called. I want to return the pointer so that the deep copy of the large data is not needed and memory leak is nicely handled. Can someone let me know how to do it? Here is something come up in my mind: boost::shared_ptr< std::vector<int> > getV(){ boost::shared_ptr< std::vector<int> > v; v->push_back(1); v->push_back(2); // bla bla bla return v; } int main(){ boost::shared_ptr< std::vector<int> > v = getV(); std::cout << v->at(0); return 0; } I got the following message when run the program: /usr/include/boost/shared_ptr.hpp:253: T* boost::shared_ptr<T>::operator->() const [with T = std::vector<int, std::allocator<int> >]: Assertion `px != 0' failed. Aborted How can I get it correct? Is there any deep copy when the getV() return the shared_ptr? Thanks a lot. zl2k

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