April 2006 - Boost - lists.boost.org

[plugin] problems with plugin base class
by Tim Blechmann 29 Apr '06

29 Apr '06

hello boost devs, using the plugin library from the boost-sandbox, i experience problems in the following two cases: - the base class of the plugin accepts parameters: *** Creating an instance of plugin class Could not load weapon: Boost.Plugin: Can't cast to the right factor type - the base class of plugin is inherited from another class: Could not load weapon: Boost.Plugin: Could not open shared library './library.so' i've added both cases to the example sources and attached them, would be awesome, if this could be made working ... although i'm not really familiar with the plugin internals, i'd be willing to test any code, the plugin developers send me... thanks in advance ... tim ps: please cc any response to me, since i'm a posting-only member. pps: since sourceforge currently seems to have some problems with synchronizing anonymous and developer's cvs, please also send me patches -- TimBlechmann(a)gmx.de ICQ: 96771783 http://www.mokabar.tk Linux is like a wigwam: no windows, no gates, apache inside, stable.

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Re: [boost] Possible class submission: Sparse Array
by Sohail Somani 29 Apr '06

29 Apr '06

> -----Original Message----- > From: boost-bounces(a)lists.boost.org > [mailto:boost-bounces@lists.boost.org] On Behalf Of Spencer Collyer > Sent: Thursday, April 27, 2006 12:11 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] Possible class submission: Sparse Array > > On Wed, 26 Apr 2006 12:33:06 -0700, Sohail Somani wrote: > > > Would there be a bounds type for specifying runtime bounds? > It seems the > > upper bound if specified, can only be specified at compile > time and this > > would limit the size of your arrays... Or is this by design? > > Because the bounds checking is specified using an inherited > policy class, > there is in principle no reason why run-time bounds cannot be > used, and I > did indeed look at doing this. I had figured this was the case, just wasn't sure :) > The option I came up with was to have a set_limit function on > the bounds > policy which you would call to define the limits at run time. The only > reason I haven't gone ahead and done the work to implement run-time > limits as yet is because I'm still not sure about the answers to a few > questions: I think you can have the sparse array implementation have an overloaded constructor that takes an instance of the policy. With a set_limit you may end up having invalid arrays for some length of time. Then, I don't think there is anything stopping you from having a reset_bounds/resize type function, but I'd rather only have them be set once as you suggested. To be honest, I'm quite used to having runtime dimensions specified and ublas's sparse arrays interface is pretty good this way. Thanks for your email! Sohail

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Report from Berlin C++ Standards Committee meeting
by Beman Dawes 29 Apr '06

29 Apr '06

The C++ Standards Committee met last week in Berlin, Germany. Of interest to Boosters: * All of TR1 except special functions has been voted into C++0x, the next standard. Special functions were supported by the Library Working Group (LWG), including vendors such as Dinkumware, but they didn't fly in full committee. Compiler vendors indicate great worry about support costs. This vote isn't necessarily the end of the story since support for special functions was strong, although not quite enough to achieve the consensus needed. (The committee will only go ahead if there is consensus - a simple majority isn't good enough.) * Boost Filesystem was voted into TR2. * Boost Lexical Cast has been tentatively accepted by the LWG for TR2. * Boost Any has been tentatively accepted by the LWG for TR2. * A Boost Date-Time query was presented at the last meeting, and LWG members again in Berlin indicated interest in seeing a full proposal for TR2. * A Boost Networking [asio] query was presented, and the LWG has indicated their interest in a full proposal for TR2. The developer of a competing proposal has graciously thrown his support behind the Boost proposal, and may propose some additional higher level functionality. * Boost Threads has been reaffirmed as the LWG's choice as the basis for a TR2 threading library. Pete Becker's www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1907.html is the most recent version of the proposal. It will be refined and modified as work progresses. Howard Hinnant plans to propose unifying the lock classes into scoped_lock/shared_lock and possibly one other class. Pete will propose a function to access the underlying operating system handles to allow access to non-portable functionality. I've committed to review error handling to ensure handling of operating system errors is consistent between all TR2 libraries. * It looks more and more likely that Concepts will go into C++0x. If Concepts do go into the core language, the LWG has indicated their intent to percolate Concepts throughout the Standard Library. (Concepts were being held up by two competing proposals, but those two proposals are in process of being coalesced into a single proposal by Bjarne Stroustrup and Doug Gregor.) The next committee meetings are: October, 2006, Portland, Oregon. See www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n1946.htm Spring, 2007, Oxford, England. Fall, 2007, Kona, Hawaii This coming October is the deadline for TR2 proposals. See www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1810.html --Beman

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[plugin] problem with headers in different objects
by Tim Blechmann 29 Apr '06

29 Apr '06

hi all, currently it's not possible to include boost/plugin.hpp or boost/plugin/virtual_constructors.hpp from different object files with gcc-3.4.6 including plugin.hpp from two object files: tim@laptop ~/sandbox $ g++ main.cpp t1.o t2.o t2.o: In function `boost::dynamic_visitor_base::~dynamic_visitor_base()': t1.cpp:(.text+0x0): multiple definition of `boost::dynamic_visitor_base::~dynami c_visitor_base()' t1.o:t1.cpp:(.text+0x0): first defined here t2.o: In function `boost::dynamic_visitor_base::~dynamic_visitor_base()': t1.cpp:(.text+0x28): multiple definition of `boost::dynamic_visitor_base::~dynam ic_visitor_base()' t1.o:t1.cpp:(.text+0x28): first defined here t2.o: In function `boost::dynamic_visitor_base::~dynamic_visitor_base()': t1.cpp:(.text+0x50): multiple definition of `boost::dynamic_visitor_base::~dynam ic_visitor_base()' t1.o:t1.cpp:(.text+0x50): first defined here t2.o:(.bss+0x0): multiple definition of `(anonymous namespace)::_1' t1.o:(.bss+0x0): first defined here t2.o:(.bss+0x1): multiple definition of `(anonymous namespace)::_2' t1.o:(.bss+0x1): first defined here t2.o:(.bss+0x2): multiple definition of `(anonymous namespace)::_3' t1.o:(.bss+0x2): first defined here t2.o:(.bss+0x3): multiple definition of `(anonymous namespace)::_4' t1.o:(.bss+0x3): first defined here t2.o:(.bss+0x4): multiple definition of `(anonymous namespace)::_5' t1.o:(.bss+0x4): first defined here t2.o:(.bss+0x5): multiple definition of `(anonymous namespace)::_6' t1.o:(.bss+0x5): first defined here t2.o:(.bss+0x6): multiple definition of `(anonymous namespace)::_7' t1.o:(.bss+0x6): first defined here t2.o:(.bss+0x7): multiple definition of `(anonymous namespace)::_8' t1.o:(.bss+0x7): first defined here t2.o:(.bss+0x8): multiple definition of `(anonymous namespace)::_9' t1.o:(.bss+0x8): first defined here collect2: ld returned 1 exit status t1.cpp & t2.cpp contain: #include "boost/plugin.hpp" main.cpp contains: int main(){return 0;} similar things happen with boost/plugin/virtual_constructors.hpp ... not sure, if it's a but in the library, or a compiler bug ... cheers ... tim -- TimBlechmann(a)gmx.de ICQ: 96771783 http://www.mokabar.tk You can play a shoestring if you're sincere John Coltrane

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Re: [boost] [Boost Review] Do property_tree and program_options overlap?
by bwood 29 Apr '06

29 Apr '06

: "Gennadiy Rozental" <gennadiy.rozental_at_[hidden]> wrote in message :>"Ivan Vecerina" <ivec_at_[hidden]> wrote in message :> It's not like boost::serialize currently dominates the world :> of persistent storage. : :So? I see a potencial for it to become a standard like iostreams now. I'm glad you added the part about iostreams as I think it hits the nail on the head. I agree with Andrei's opinions of iostreams. http://groups.google.com/group/comp.lang.c++.moderated/browse_frm/thread /86a5a3f804c84ea4/48842ae2fd029ce6?hl=en#48842ae2fd029ce6 While iostreams is a part of the standard that doesn't mean it is a healthy part of it. I think eventually someone will develop something better. You've been touting multi_index here as well. I wouldn't balk if you suggested adding it to the standard. Brian www.webEbenezer.net

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Property Tree library review
by Jose 29 Apr '06

29 Apr '06

I vote a weak NO. I would change this to yes once the library has some decent functionality to select values by path (see the related thread on testing the PT xml parser) I also have some general comments about the name, scope and design of the library: 1. The library name I think the library should be named after what it does (not how it does it). The property tree is the container but in this case the library is about program configuration - Boost.ProgramConfiguration (there are other libraries where a more technical name is better because of the library scope, like the property map library, but not for this one) 2. Relation to other libraries I think the relation to the Boost.ProgramOptions library is not clear. Maybe it should ! Without having used the PO lib, I think the PT lib is a superset, focusing on both command-line and file-based configuration. The use of the Spirit library for the xml parser is good. Using other boost libraries like serialization, .. do not seem correct for this specific library. 3. The scope This is the strong point of this library. I has the potential to be widely useful as it can be used in any program to load and save the program settings 4. The design * The strong points: I think the only strong point is the focus on simplicity. I think this attracts everybody attention as the library can be quickly used and everybody sees and specific use right away but I see many design issues too - see below * The weak points: a) The container The use of a generic tree container has not been seriously considered. The argument against using a generic container is that it would complicate the library. I don't agree. For a specific example check the tree.hh library: an STL-like C++ tree class http://www.aei.mpg.de/~peekas/tree/ This library provides a generic tree container and well thought-out interfaces. It is as easy or easier to use than the PT lib b) The parsers (library vs utilities) It is not clear whether the parsers are utilities or whether the PT lib is supposed to provide some framework to build specific parsers. E.g. * How easy is to use this existing file format with ":" separator name1: value1 name2: value2 * How easy is to use a more advanced format, e.g. a CSS file h1 { font-family: arial; font-size: 12px; } .show { ... } This also should be explained in the docs. d) Relation to standards The library has been presented many times as a sort of DOM ... >From the docs: "One can think of it as a sort of Document Object Model, which is minimalistic, ..." I think this is a fallacy, because there are standards like the W3 DOM and XPath that are widely useful and widely used, and taking these out of the design just limits what the library can do (if the standards were both not widely useful and widely used then I would think otherwise). Again, the argument is simplicity but I think with a generic tree container, like tree.hh, these standards can be supported without complicating the usage. Conclusion ---------------- Maybe one way out of this conundrum is to consider the current library as the basic one and later have an advanced version that really provides the generic container and the proper query mechanisms.

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[Boost-bugs] [ boost-Support Requests-1478619 ] new timezone db file for #1471723 - 2007 DST support
by SourceForge.net 29 Apr '06

29 Apr '06

Support Requests item #1478619, was opened at 2006-04-28 16:01 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1478619&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Robert Hodge (quatras) Assigned to: Nobody/Anonymous (nobody) Summary: new timezone db file for #1471723 - 2007 DST support Initial Comment: This relates to support item #1471723. The attached file is a suggested replacement for the timezone.csv file which will assist in supporting the upcoming DST rule changes in 2007 ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1478619&group_… ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[type_traits][regex] VC++ __fastcall /clr
by Edward Diener 28 Apr '06

28 Apr '06

Since no one responded to this in the boost user group, I will post it here in this group. When compiling managed code in VC++ .NET, which is any of the /clr compiler options, the programmer can mix both CLR classes and regular C++ classes. In the regular C++ classes, Boost should work fine. The VC++ macro which tells one that managed code of any kind is being compiled is _MANAGED, which is defined if managed code is being compiled else it is not defined. So when any of the /clr compiler options are being used _MANAGED is defined, else it is not defined. The VC++ compiler issues compiler warning C4561 whenever managed code is being compiled and __fastcall shows up as a calling convention in any way. Obviously the programmer can turn off this warning via a VC++ #pragma, but I am wondering if Boost could not change some of its headers to avoid this warning. In Boost bind and mem_fn, the programmer has to specifically ask for __fastcall support via special Boost macros to have any functions declared with the __fastcall calling convention, so nothing should be done there since it is clearly a programming error if he does so while compiling managed code. However there are two other places in Boost which I have discovered where functions with the __fastcall calling convention are declared without the programmer doing anything. The first, and most cumbersome reagrding warning messages, is in type_traits in the helper header files type_traits\detail\is_mem_fun_pointer_tester.hpp and type_traits\detail\is_function_pointer_tester.hpp. Since many other libraries, lambda in my case recently, uses type_traits, might not these headers be changed so that when VC++ is the compiler and _MANAGED is defined, the __fastcall versions of these helper functions are not declared ? The second, which I have not encountered but which I saw while searching through Boost header code, is in regex\config.h and I do not know, given some other macros there, whether BOOST_REGEX_CALL can ever be __fastcall when compiling with /clr, but if it can perhaps a change can be made there also. I know that it is not the purpose of Boost to try to accomodate C++ .NET programmers creating /clr compilations using Boost, especially when just warnings and not errors are issued. But in this case, using the predefined macro _MANAGED in VC++ and BOOST_MSVC, it would seem this acoomodation could be made. So I would like the Boost developers of type_traits, especially since it is used by so many other Boost libraries, and regex to consider it.

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[Boost-bugs] [ boost-Bugs-1478435 ] boost/crc.hpp used non-standard conforming syntax
by SourceForge.net 28 Apr '06

28 Apr '06

Bugs item #1478435, was opened at 2006-04-28 16:48 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1478435&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Mattias Ellert (mattiasellert) Assigned to: Nobody/Anonymous (nobody) Summary: boost/crc.hpp used non-standard conforming syntax Initial Comment: [ellert@ellert ~]$ g++ -pedantic -x c++ /usr/include/boost/crc.hpp /usr/include/boost/crc.hpp:464: error: ISO C++ forbids variable-size array `table_type' [ellert@ellert ~]$ g++ --version g++ (GCC) 3.4.4 20050721 (Red Hat 3.4.4-2) Copyright (C) 2004 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. The header file uses a non-constant expression as the size in an array declaration. This is not valid c++, and the compiler rejects it when using the -pedantic flag. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1478435&group_… ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Class views on an associative container
by SeskaPeel 28 Apr '06

28 Apr '06

Hi list, I'm looking for a "multi-class container", with access to sub-containers of elements depending on their class. All elements are derived from the same base class, and I want to have "views" of containers of final classes, or even intermediate classes. This container would be associative, like a map. As instance if I have // Base class class A {} ; // Intermediate classes class B : public A {} ; // Final classes class C : public B {} ; class D : public B {} ; class E : public A {} ; I want a container that can hold any A-derived class, on which I could have views of sub containers of class C, D or E, and even a sub container of intermediate class B. I looked at multi-index, but no such feature seems to be feasible. And I have no need of multiple indices, as I access all theses elements by their ID which is a member of A. Any hint on how I could implement this? Cheers, SeskaPeel.

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