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RE: [Boost-Users] Is intrusive_ptr the thing to use?
by Hickman, Greg 28 Nov '02

28 Nov '02

From: Peter Dimov [mailto:pdimov@mmltd.net] > From: "Hickman, Greg" <greg.hickman(a)lmco.com> > > > From: Peter Dimov [mailto:pdimov@mmltd.net] > > > If 'f' is virtual, have the object store a weak_ptr to itself: > > > > > > class X > > > { > > > private: > > > > > > weak_ptr<X> weak_this; > > > > > > X(); > > > X(X const &); > > > X& operator=(X const &); > > > > > > public: > > > > > > static shared_ptr<X> create() > > > { > > > shared_ptr<X> px(new X); > > > px->weak_this = px; > > > return px; > > > } > > > > I must be missing something here, because it appears as though you > > can't derive a Y from X and still initialize X::weak_this. > > You could simply make X::weak_this and X::X() protected... > although if you follow the design rule that says that > non-leaf classes should be abstract (and if possible contain > no data) this shouldn't be necessary, as X as pictured above > would be a leaf. Its seems the leaf itself must implement the factory method/weak_this idiom. This initially didn't seem like a good idea in our case since clients write the leaves - we only provide X. But on second thought, perhaps two alternatives are (1) provide a helper template for clients to use when deriving from X to automatically declare the static create()/weak_this pair, or (2) use an intrusive reference counting approach for X. If an intrusive approach ultimately works better for us, what should I do as a boost 1.29.0 user: use counted_base/shared_from_this, or intrusive_ptr (which I admittedly haven't even looked at)? Any suggestions you have are more than welcome. -Greg

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RE: [Boost-Users] ublas::matrix sharing storage with ublas::vecto r
by Scott Sinclair 28 Nov '02

28 Nov '02

Sorry, I obviously misunderstood your original question :( On 28/11/2002 03:46 Stephen Crowley wrote: > What do you mean by "just use it as" ? > For example.. I have a matrix<double> m(5,5); > > In some code I actually need to use it as a 5x5 matrix.. but > other parts > must reference it as a vector (to pass to another library). > > Currently I am doing something like this > > matrix<double> m(5,5); > // do stuff to m > vector<double> v(25); > v.data() = m.data(); > // pass v to library > // get results back > m.data() = v.data(); > > This is obviously not optimal.. and if both m.data() and > v.data() pointed to > the same location in memory the problem would be solved. > > I suppose I might be able to get around it by making my own > storage class > that allows you to specify a location and size instead of > allocating one > itself. > > --Stephen The contents of this email may be confidential. Unauthorised use is prohibited. Umgeni Water does not accept liability for any statements and opinions which are the sender's own view and not expressly made on its behalf.

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RE: [Boost-Users] Is intrusive_ptr the thing to use?
by Hickman, Greg 27 Nov '02

27 Nov '02

> -----Original Message----- > From: Peter Dimov [mailto:pdimov@mmltd.net] > Sent: Tuesday, November 26, 2002 6:49 AM > To: Boost-Users(a)yahoogroups.com > Subject: Re: [Boost-Users] Is intrusive_ptr the thing to use? > If 'f' is virtual, have the object store a weak_ptr to itself: > > class X > { > private: > > weak_ptr<X> weak_this; > > X(); > X(X const &); > X& operator=(X const &); > > public: > > static shared_ptr<X> create() > { > shared_ptr<X> px(new X); > px->weak_this = px; > return px; > } I must be missing something here, because it appears as though you can't derive a Y from X and still initialize X::weak_this. -Greg

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solaris gcc 3.2 stlport regexp (bug?)
by c_twiner 27 Nov '02

27 Nov '02

Hi all, When I use bjam to compile the regexp library it compiles seems happy and then no code works properly, seg faults, rubbish results etc. When I compile using a modified make file of the shared-gcc.mak (modifications follow): INCLUDES= -I/export/home/ctwiner/STLport-4.5.3/stlport -L/export/home/ctwiner/STLport-4.5.3/lib LIBS= -lstlport_gcc_stldebug # compiler: CXX=g++ LINKER=g++ -shared -fPIC # # compiler options for release build: # C1=-c -O2 -I../../../ -fPIC # # compiler options for debug build: # C2=-c -g -I../../../ -fPIC It builds but even linking to the .so created causes a seg fault. I know that stlport is ok because I have programs linking to the new version using std::map's vectors and strings. I posted another message using 2.95 which had the same/similar problems. Everything seems to build fine but running causes seg faults. The solaris version is 2.8. When using the bjam built files and trying to run the compiled regexp_tests the locale_impl.h of stlports asserts at line 60. latest downloads of all librarys have been used. TIA Chris

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ublas::matrix sharing storage with ublas::vector
by Stephen Crowley 27 Nov '02

27 Nov '02

It is possible for a vector and a matrix to share the same storage, as long as the dimensions agree? Some of the algorithms I am implementing require some objects to be treated as an arbitrarily sized matrix, and sometimes as a vector, and it would be convient to have a matrix and a vector share the same memory. -- Stephen

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Link problem with boost::signals and console applications in MS Visual C++ 6 / Windows
by Klaus Nowikow 26 Nov '02

26 Nov '02

Hi all, a colleague asked me to post the following question: When using the boost signal lib in VC6 (Win32 Console Application), the linker produces the following errors: msvcprt.lib(MSVCP60.dll) : error LNK2005: "public: __thiscall std::_Lockit::~_Lockit(void)" (??1_Lockit@std@@QAE@XZ) already defined in libcpd.lib(iostream.obj) msvcprt.lib(MSVCP60.dll) : error LNK2005: "public: __thiscall std::_Lockit::_Lockit(void)" (??0_Lockit@std@@QAE@XZ) already defined in libcpd.lib(iostream.obj) MSVCRT.lib(MSVCRT.dll) : error LNK2005: "public: __thiscall exception::exception(class exception const &)" (??0exception@@QAE@ABV0@@Z) already defined in LIBCD.lib(stdexcpt.obj) MSVCRT.lib(MSVCRT.dll) : error LNK2005: "public: __thiscall exception::exception(void)" (??0exception@@QAE@XZ) already defined in LIBCD.lib(stdexcpt.obj) MSVCRT.lib(MSVCRT.dll) : error LNK2005: "public: virtual __thiscall exception::~exception(void)" (??1exception@@UAE@XZ) already defined in LIBCD.lib(stdexcpt.obj) LINK : warning LNK4098: defaultlib "MSVCRT" conflicts with use of other libs; use /NODEFAULTLIB:library Debug/boost.exe : fatal error LNK1169: one or more multiply defined symbols found There seems to be a conflict between the libraries signals.lib, libcpd.lib and libcd.lib. When I try to ignore the libraries libcpd.lib and libcd.lib in the project settings, other linker errors occur when I use std::cout for example: main.obj : error LNK2001: unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > std::cout" (?cout@std@@3V?$basic_ostream@DU?$char_traits@D@std@@@1@A) Is there a way to use the boost::signals library in a Win32 Console Application in VC6? Regards, Klaus

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Is intrusive_ptr the thing to use?
by Hickman, Greg 26 Nov '02

26 Nov '02

I need an object managed through a shared_ptr to be able to pass itself (i.e., this) to another object which also expects a shared_ptr. Is there a preferred implementation technique for this when using the boost smart pointers? I think I've seen conversation in the past about deriving from boost::counted_base and calling shared_from_this(), but I think I also remember seeing comments to the effect that this is going away. OTOH, I know there's something called intrusive_ptr that's currently undocumented. Should I be using one of these approaches? If the answer is intrusive_ptr, are there docs? Should I roll my own? What's a Booster to do? -Greg

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matrix inside a matrix?
by Stephen Crowley 26 Nov '02

26 Nov '02

Is it possible to define a matrix that is part of a larger matrix, without having to create temporaries and copy part of the larger? /----------\ | | | | SM | | |----| LM | | | \----------/ I need to extract a sub-section of a matrix, multiply it, and then copy it back. I am currently using a temporary, but I have a feeling there must be a better way. -- Stephen

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RE: [Boost-Users] Is intrusive_ptr the thing to use?
by Mark Storer 25 Nov '02

25 Nov '02

>The only problem with it currently is that the >smart_class MUST be managed with smart_ptrs, >if you try to 'delete' it, it will try to delete >itself and crash. This seems like a problem that could be overcome through overloading the "delete" operator. Perhaps if you declared your delete operator as protected (or private), and then made the smart pointers you wanted to use friends? That would force you to use a specific set of smart pointer classes, but that doesn't sound like it would be a problem in your case. It's fixing the symptom rather than the disease, but is better than nothing. Turning runtime errors into compiletime errors is always a Good Thing. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard;

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RE: [Boost-Users] Re: uBLAS, MTL performance tests.
by Randy Bowen 25 Nov '02

25 Nov '02

Actually, default behavior of the IDE is to define "_DEBUG" in the debug configurations, and "NDEBUG" in the release versions. Those are set as defaults for all files, but may be overridden on a case-by-case basis as necessary. This is a bit off topic for the Boost list. If you have other questions in this area, feel free to email me directly. Randy Bowen rbowen(a)stamps.com -----Original Message----- From: Jon Agiato [mailto:JonAgiato@nyc.rr.com] Sent: Friday, November 22, 2002 6:32 PM To: Boost-Users(a)yahoogroups.com Subject: Re: [Boost-Users] Re: uBLAS, MTL performance tests. Thanks Randy! Would you know if it is also set for release by default as well? Jon Agiato JonAgiato(a)nyc.rr.com ----- Original Message ----- From: Randy Bowen To: Boost-Users(a)yahoogroups.com Sent: Friday, November 22, 2002 6:40 PM Subject: RE: [Boost-Users] Re: uBLAS, MTL performance tests. > > > add -DNDEBUG to command line arguments. Unfortunately > I don't know where exactly you can edit command line > arguments in VC.NET. > > Alexei. > In VC.NET, this can be set under Project Properties -> C/C++ -> Preprocessor -> Preprocessor Definitions. (It's normally preset for debug configurations.) Randy Bowen Yahoo! Groups Sponsor ADVERTISEMENT Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. [Non-text portions of this message have been removed] Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

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