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[Formal review request] const_string
by Maxim Yegorushkin 19 Oct '04

19 Oct '04

Recent postings showed interest in an immutable string facility [*]. Its interface and implementation has now reached a stable state (I hope). I am formally requesting that const_string be added to the review queue. The documentation can be found here: http://conststring.sf.net/ (it's not in a final state, but I'm going to extend it while it stays in the queue) [*] http://aspn.activestate.com/ASPN/Mail/Message/boost/2180929 -- Maxim Yegorushkin

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[serialization] warnings while building Boost.Serialization
by Christoph Ludwig 19 Oct '04

19 Oct '04

Hi, when building Boost.Serialization my compiler (gcc 3.4.2 on i686-pc-linux-gnu) issues some warnings. They are no big deal for me, but I think they can (and should) easiliy be avoided. * In wchar_from_mb.hpp, line 107, we have for(int i = 0; i++ < MB_CUR_MAX;){ //... On my system, MB_CUR_MAX evaluates to an expression of type size_t, whence the compiler warns about a comparison between signed and unsigned. I don't know which type MB_CUR_MAX is supposed to have according to the relevant standards, but I think it is safe to assume that the value of MB_CUR_MAX will always fit into a signed int. I therefore propose to change above line into: for(int i = 0; i++ < int(MB_CUR_MAX);){ //... * In basic_xml_archive, line 38, I get a warning about a potentially uninitialized variable msg: virtual const char *what( ) const throw( ) { const char *msg; switch(code){ case xml_archive_parsing_error: msg = "unrecognized XML syntax"; break; case xml_archive_tag_mismatch: msg = "XML start/end tag mismatch"; break; default: archive_exception::what(); // (*) } return msg; } I think the compiler caught a genuine mistake and the line marked (*) should read msg = archive_exception::what(); Regards Christoph -- http://www.informatik.tu-darmstadt.de/TI/Mitarbeiter/cludwig.html LiDIA: http://www.informatik.tu-darmstadt.de/TI/LiDIA/Welcome.html

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[signals]
by Roland Schwarz 19 Oct '04

19 Oct '04

I wonder if it is possible to use the signal library to do interprocess/(synchronized)interthread calls. Would it be easily possible to extend it into this aerea if not already possible? Am I considering the wrong library? If yes, could anyone please suggest a better approach? Thanks, Roland

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RE: [boost] Re: Library Proposal: database (boost::db)
by Brian Braatz 19 Oct '04

19 Oct '04

> On Behalf Of Michael van der Westhuizen > >> > >>Can you compae it with Database Template Library > >>http://dtemplatelib.sourceforge.net/index.htm > >>? > > > > > > Just an FYI here- I recently evaluated the DTL and it uses RTTI > > internally- > > Thoughts on OTL? > > http://otl.sourceforge.net/ > > I've used it a few times, and it's extremely capable. > > Michael Thanks for the link- that is very interesting. It looks like I can get what I need from it. IN rough comparison, it looks like the MYSQL++ library may be a bit more "normal" looking to DB developers who are used to disconnected recordsets, but it looks like the OTL libraries have far greater power. At the end of the day- I believe that a balance between "recordset"-ish model of MYSQL++ and the power of OTL would be a good combination. A library is not useful if it is too hard to get up to speed on OR too terribly different from what people are used to.

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Serialization - building shared libs
by Neal Becker 19 Oct '04

19 Oct '04

I brought up the topic that int the current cvs serialization libs are only built static, not shared. The reason for this is that the library uses this construct: ,----[ /home/nbecker/stuff/A.hpp ] | // {{{ struct A | | struct A { | int i; | A() { i = 1; } | static const A instance; | }; | | // }}} | | extern const A A::instance = A(); `---- If this is included into 2 shared libraries, will A::instance be shared? I have tested this on Linux. If you dlopen 2 different shared libs, it will work correctly, if you set the flags RTLD_NOW|RTLD_GLOBAL. Since this will work correctly on some systems, I would like to see this supported. It is impossible to use serialization with boost::python without shared libs.

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RE: [boost] Object Pool
by Abdullah Sowayan 18 Oct '04

18 Oct '04

Please ignore my prior question. I finally understood the whole process. Abdul -----Original Message----- From: Abdullah Sowayan Sent: Monday, October 18, 2004 11:53 AM To: boost(a)lists.boost.org Subject: [boost] Object Pool I am trying to use the Object Pool library. In the documentation I came across the following (html table): t.construct(???) ElementType * ElementType must have a constructor matching ???; the number of parameters given must not exceed what is supported through pool_construct <http://www.boost.org/libs/pool/doc/implementation/pool_construct.html> Allocates and initializes an object of type ElementType. If out of memory, returns 0. Amortized O(1). 1) What is "???" referring to? 2) What is I have the following class class A { public: A(int i, std::string s); ... }; How can I create a pool of As? Note that there isn't a constructor A::A( ) that takes nothing. How can I say that the pool for instance would initialize all objects to A::A(1, "Howdy") Thanks, Abdul _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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Re:Re: [boost] Sprit-1.6 and latest boost
by Robert Ramey 18 Oct '04

18 Oct '04

Joel de Guzman wrote: > And thank you too for fixing all apply_if's and stuff in all spirit > related libraries in the boost CVS. And thanks for doing the same for the serialization library! Robert Ramey

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Object Pool
by Abdullah Sowayan 18 Oct '04

18 Oct '04

I am trying to use the Object Pool library. In the documentation I came across the following (html table): t.construct(???) ElementType * ElementType must have a constructor matching ???; the number of parameters given must not exceed what is supported through pool_construct <http://www.boost.org/libs/pool/doc/implementation/pool_construct.html> Allocates and initializes an object of type ElementType. If out of memory, returns 0. Amortized O(1). 1) What is "???" referring to? 2) What is I have the following class class A { public: A(int i, std::string s); ... }; How can I create a pool of As? Note that there isn't a constructor A::A( ) that takes nothing. How can I say that the pool for instance would initialize all objects to A::A(1, "Howdy") Thanks, Abdul

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boost::shared_ptr interface
by David M. Jones 18 Oct '04

18 Oct '04

I ran into a situation (see my "smart list" post on the boost users group) where I wanted to create a custom allocator whose pointer typedef is boost::shared_ptr. In other words, the code would look something like: template <typename T> class my_allocator { public: typedef boost::shared_ptr<T> pointer; }; The problem with doing this is that boost::shared_ptr<T> does not have the same "interface" as the equalivalent raw pointer type T*. (I use the term interface in the generic programming/template sense; not in the object oriented sense.) One example is that there is no operator= on boost::shared_ptr that takes a raw pointer; instead reset() must be used. Here are my questions: (1) What advantage does this change of interface serve that makes it worth breaking potential operations such as that above? (2) Does anyone have ideas on how to get around this problem? I toyed with the idea of writing a class that derives from boost::shared_ptr and has the interface that I desire -- anybody have thoughts on this? Thanks, David M. Jones

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explicit shared_ptr(weak_ptr<Y> const & r);
by John Torjo 18 Oct '04

18 Oct '04

Hi Peter, Just a thought: perhaps this constructor: explicit shared_ptr(weak_ptr<Y> const & r); should be private, and the only way to create a shared_ptr from a weak_ptr is: shared_ptr<T> val = weak->lock(); This way, the shared_ptr public constructors will never throw. Users will not make mistakes like this: shared_ptr<T> val = weak; I'm saying this, because I just made this mistake a few hours ago... After a while, the shared_ptr<> constructor started to throw at me ;) Best, John -- John Torjo, Contributing editor, C/C++ Users Journal -- "Win32 GUI Generics" -- generics & GUI do mix, after all -- http://www.torjo.com/win32gui/ -- v1.5 - tooltips at your fingertips (work for menus too!) + bitmap buttons (work for MessageBox too!) + tab dialogs, hyper links, lite html

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