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[filesystem + iterator] directory iterator problem
by Vladimir Prus 08 Jul '04

08 Jul '04

There's a bug report on sourceforge: https://sourceforge.net/tracker/index.php?func=detail&aid=937606&group_id=7… which boils down to the fact that directory_iterator it(...); path p = *it++; does not work correctly. The exact problem is that the above line return a copy of the iterator, and increments 'it', but both iterators have shared_ptr to the same internal structure, so by time user deferences the copy, it gets the next file in the directory. The filesystem lib sources contain the following comment: The *r++ requirement doesn't appear to apply to the new single_pass_traversal category Thus I'm leaving the proxy out pending confirmation from the N1477 authors I'm not sure I understand that. It seems that *r++ should work, since signle pass iterator requires that r++ should work and return object of type X (call it r2), and the reabable iterator requires that *r2 should work. Am I wrong? And BTW, don't the above requirements mean r++ cannot return a proxy object, but only a real copy of the iterator? - Volodya

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result_ofOp, operator should be a template parameter
by Andy Little 08 Jul '04

08 Jul '04

An example that I think demonstrates the superiority of this: binary_operation<A,Op,B>::result_type result; over this: result_of_plus<A, B>::type result; in this directory: http://www.servocomm.freeserve.co.uk/Cpp/physical_quantity/source/ array_calcs.hpp and array_calcs.cpp. The example shows an expression template for arrays based on the examples in: http://osl.iu.edu/~tveldhui/papers/techniques/ (BTW this is part of my next distro so no guarantee it works in pqs-1-01-04 , though should be ok.) Specifically making the operator a template parameter makes it generic IMHO and much reduces the work required. If an expression is required in "typeof" then it cant work generically , unless operators are allowed as template params And a generic "placeholder"operator param is included. (Simple promotion is inadequate for udts) Simple useage of binary_operation described here: http://www.servocomm.freeserve.co.uk/Cpp/physical_quantity/binary_operation… regards Andy Little

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Review Wizard Needed
by David Abrahams 08 Jul '04

08 Jul '04

After pioneering the role of Boost Review Wizard, and doing a darned fine job of it, Thomas Witt has resigned, leaving this important position open. The moderators are now accepting applications for his replacement. The responsibilities of the review wizard are listed here: http://www.boost.org/more/formal_review_process.htm#Wizard. If you're interested in making a crucial contribution to the future of Boost, please send a short note to boost-owner(a)lists.boost.org with a sentence or two about why you'd like to be the next Review Wizard. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com

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RE: [boost] Generalizing the shared_ptr
by Hurd, Matthew 08 Jul '04

08 Jul '04

> Behalf Of Maciej Sobczak <snip bits everywhere> > Hi, Hi Maciej, > Is it possible to achieve the same results with the existing Boost > libraries? I think so. Have a gander at http://www.boost.org/libs/smart_ptr/sp_techniques.html and see if that meets cooks your goose. Regards, Matt Hurd. _________________ +61.2.8226.5029 hurdm(a)sig.com Susquehanna _________________ IMPORTANT: The information contained in this email and/or its attachments is confidential. If you are not the intended recipient, please notify the sender immediately by reply and immediately delete this message and all its attachments. Any review, use, reproduction, disclosure or dissemination of this message or any attachment by an unintended recipient is strictly prohibited. Neither this message nor any attachment is intended as or should be construed as an offer, solicitation or recommendation to buy or sell any security or other financial instrument. Neither the sender, his or her employer nor any of their respective affiliates makes any warranties as to the completeness or accuracy of any of the information contained herein or that this message or any of its attachments is free of viruses.

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is_polymorphic type_trait question
by Robert Ramey 07 Jul '04

07 Jul '04

I have the following little test program #include <boost/static_assert.hpp> #include <boost/type_traits/is_polymorphic.hpp> struct vbase { }; struct derived : public virtual vbase { }; // VC 7.1, borland 5.51 and Commeau trap here (gcc 3.2 doesn't trap here!) BOOST_STATIC_ASSERT(boost::is_polymorphic<derived>::value); // everything including gcc traps here ! BOOST_STATIC_ASSERT(boost::is_polymorphic<vbase>::value); int main(int argc, char *argv[]) { } This suggests to me that is_polymorphic returns true for a class derived virtually from a base class under the gcc compiler even though the base class has no virtual function!

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Re:RE: [boost] Does anyone have an is_virtual_base_and_derived ?
by Robert Ramey 07 Jul '04

07 Jul '04

SRobb(a)reflectionsinteractive.com > I wrote that very thing a year or so ago for the purpose of testing if a > base pointer type can be statically downcast to a derived type. My problem exactly ! So I think this is what I need. Just to prove once again that no good deed goes unpunished - a) at a very minimum I want to add a boost copyright license and for that I would need your name which wasnn't on your post. b) any chance of this getting "boostified" with a couple of tests an maybe a micro-review?. c) I notice that the type_traits already in the library are much - much more elaborate due to the variations in compilers. Any chance of this getting subjected to this kind of treatment? I'm now testing this on my problem. Robert Ramey

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Boost Mathematicians
by Tom Brinkman 07 Jul '04

07 Jul '04

What is the current status of all Boost mathmatical, statistical and econometric libraries currently in development? The collection of boost math libraries that are currently included in the library are world-class and provide a wonderful foundation to build-upon. However, many areas of advanced statistical and mathmatical inference are not currently being addressed by any of the boost libraries. Is there currently a way for those boost developers with a background in mathmatics to coordinate their efforts. If not, why not? Lets get such a discussion started. A continued and regular dialog of mathmatics as it relates to boost library development would be of great use, primaryily to avoid overaping our efforts. If your a mathmetician and agree with me that boost is a great foundation to build-upon, let the group/me know. Points for Discussion: 1) We should keep a seperate list of boost::math libraries that are currently under development and provide a forum for advanced discussions. How can we do this? 2) We need a way to attract the best mathmaticians in the world. How can we make the boost libraries an even more attractive development platform for the mathemiticians? 3) We should create a list of mathmatical algorithims and libraries that are needed. 4) We need some very basic boost specific math-tutorials for our future mathemiticans and potential library writers. 5) We need to advertise to the development community about how strong of a foundation boost is for mathmatical library development. In short, lets tell the world that this is the premiere place for advanced mathmatical library development, as I believe that it could be. Comments? Regards, Tom Brinkman __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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RE: [boost] Re: [utility] boost::reset
by jhopkin＠reflectionsinteractive.com 07 Jul '04

07 Jul '04

Daniel Frey wrote: > jhopkin(a)reflectionsinteractive.com wrote: > > The STL implementation I have been using seems to allocate a buffer on first > > insertion into any container of a given type, and frees it only when it > > feels like it (often on program shut-down). > > Sounds like a pool allocator. Question: Does .clear() for your STL > return the buffer to the pool or is it still bound to the instance? What > happens in case of the .swap()-trick? I believe .clear() and the swap trick do what's expected per instance. Specifically for vector, clear generally won't release any memory to the pool; the swap trick releases it all. James Hopkin

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RE: [boost] Does anyone have an is_virtual_base_and_derived ?
by SRobb＠reflectionsinteractive.com 07 Jul '04

07 Jul '04

I wrote that very thing a year or so ago for the purpose of testing if a base pointer type can be statically downcast to a derived type. I don't claim to have tested all permutations of its usage, but it certainly worked on the cases I was testing it with. However, it does have the unfortunate side-effect of generating an 'ambiguous base' warning on the later GCCs every time it is used with a class which inherits another non-virtually. (though the traits class still gives the correct answer) If anyone can find a way of preventing this warning, or even an alternate implementation, I'd be glad to hear it. Here is my basic implementation: #include <boost/config.hpp> #include <boost/type_traits/is_convertible.hpp> namespace is_virtual_base_and_derived_detail { #ifdef _MSC_VER #pragma warning(push) #pragma warning(disable : 4250) #endif template <typename BaseImpl, typename DerivedImpl> struct tester : public DerivedImpl, virtual public BaseImpl { tester(); tester(const tester&); }; #ifdef _MSC_VER #pragma warning(pop) #endif template <typename Base, typename Derived, bool IsBaseAndDerived> struct impl; template <typename Base, typename Derived> struct impl<Base, Derived, true> { BOOST_STATIC_CONSTANT(bool, value = sizeof(tester<Base, Derived>) == sizeof(Derived)); }; template <typename Base, typename Derived> struct impl<Base, Derived, false> { BOOST_STATIC_CONSTANT(bool, value = false); }; } template <typename Base, typename Derived> struct is_virtual_base_and_derived : is_virtual_base_and_derived_detail::impl<Base, Derived, boost::is_convertible<Derived*, Base*>::value> { }; template <typename T> struct is_virtual_base_and_derived<T, T> { BOOST_STATIC_CONSTANT(bool, value = false); }; -----Original Message----- From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Robert Ramey Sent: Tuesday, July 06, 2004 6:01 PM To: boost(a)lists.boost.org Subject: [boost] Does anyone have an is_virtual_base_and_derived ? Type traits includes: ::boost::is_base_and_derived<T,U> Does anyone have a version that might be called is_virtual_base_and_derived<B, D> which would return true iff D is derived virtually from B ? Robert Ramey _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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regression tests on irix
by Toon Knapen 07 Jul '04

07 Jul '04

I'm trying to get the regression tests working again on SGI/Irix but I fail to build the html tables. Apparantly the compiler_status tool is looking for a Jamfile in the wrong place. Anybody a clue what could be happening (failing command and its output in attachment) toon generating html tables: /disk2/home/tk/boost_regression/boost/tools/regression/build/run/compiler_status --comment /disk2/home/tk/boost_regression/boost/../regression_comment.html /disk2/home/tk/boost_regression/boost cs-IRIX64.html cs-IRIX64-links.html Could not open Jamfile: /disk2/home/tk/boost_regression/Jamfile **** error return code: 1 ******** errors detected; see standard output for details ******** Failed HTML result table generation.

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