October 2004 - Boost - lists.preview.boost.org

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

19 Oct '04

(sorry been away from mail over the last 3 days)- I wanted to respond that JOAQUIN LOPEZ MU?Z Writes: "> If you'd care to sketch what kind of dynamic multi_index > you have in mind (from the user point of view) maybe we > can come out with some solid design to implement > in future releases of the lib. My intention is to stay > away from relational stuff, but I'll go for a dynamic > container if it can be made general purpose." I *very* much want to take you up on this- tonight (about 12 hours from now) I will write something up and show you what I did. > -----Original Message----- > From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] > On Behalf Of JOAQUIN LOPEZ MU?Z > Sent: Friday, October 15, 2004 12:06 PM > To: boost(a)lists.boost.org > Subject: Re: RE: [boost] Library Proposal: database (boost::db) > > Hi Brian, > > ----- Mensaje original ----- > De: Brian Braatz <brianb(a)rmtg.com> > Fecha: Viernes, Octubre 15, 2004 6:56 pm > Asunto: RE: [boost] Library Proposal: database (boost::db) > > [...] > > > > I am currently going down this exact path and wanted to share what > > I ran > > into: > > > > 1- Boost does not have a 2dim "Table<>" - i.e. a Recordset > > 2- Boost.multi_index only works with concrete structures > > I would love it if I could use that to make a dynamic Table\ > > recordset > > What do you mean by concrete structures? > > > 3- I have had to build my own Table<> by internally using > > boost.multiindex > > Do you mean, you have actually built a Table<> class > using Boost.MultiIndex? > > > [...] > > > I believe boost is missing a "recordset" analolgy and I would hope > > thatwhatever is created is not "struct only" like > > boost.multi_index. (don't > > get me wrong I LOVE the multi_index - it just doesn't work > > dynamically) > > Well, in the past I thought about what a > dynamic_multi_index_container (with run-time specification > of indices) could look like: the implementation internals > are not hard to solve with the same framework as > Boost.MultiIndex, it is the interface that I don't have a > clear idea about. Also, I don't envision a clear usage > scenario for this, and there are RTTI-like issues > involved as well (what should get<N>() return?) > > If you'd care to sketch what kind of dynamic multi_index > you have in mind (from the user point of view) maybe we > can come out with some solid design to implement > in future releases of the lib. My intention is to stay > away from relational stuff, but I'll go for a dynamic > container if it can be made general purpose. > > On another topic, have you considered Arkadiy's > RTL as another source of ideas/synergies? Seems like > Arkady sort of diverted to his BOOST_TYPEOF facility, > so I don't know what the current status of the lib is. > > Joaquín M López Muñoz > Telefónica, Investigación y Desarrollo >

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

19 Oct '04

That's cool. Thank you. Tito/Anyone It would appear that I am working on something similar (though closer to the MYSQL++ model). I am working on a wrapper over ODBC in this vein. I invite again anyone to send me private mail if this discussion gets off topic boost wise. Motivations: 1- We *need* a db layer in boost 2- I *need* to make some modifications in some existing code for a project I am working on- this may or may not be appropriate for boost- i.e. if I can do this and also somehow help a boost db along- then great > On Behalf Of Maciej Sobczak > Sent: Friday, October 15, 2004 11:51 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] Re: Library Proposal: database (boost::db) > Hi, > > Brian Braatz wrote: > > > 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. > > Just to stirr up a little bit: > > http://www.msobczak.com/prog/soci/ > > This library aims at simple usage patterns, where intuitive and almost > "embedded" syntax at at premium. A very different approach from those > you discuss, but in fact complementary and can be merged with other > approaches. > > (the code is to be modified a little bit, but what is available at the > moment works fine with Visual C++ 7.1 and g++ 3.2) > > -- > Maciej Sobczak : http://www.msobczak.com/ > Programming : http://www.msobczak.com/prog/

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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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