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[BGL] dag_shortest_paths broken?
by Vladimir Prus 11 Oct '04

11 Oct '04

Hello, it appears that the dag_shortest_paths algorithm is broken. The attached program tries to find the longest path by changing inf/comparison operators. The graph is 0 -----> 1 ------> 2 ^ | 3 ----------/ The edge weights are 1 for 0->1 and 1->2 and 2 for 3->1 and I'm searching for the longest path starting from '0'. The final result for '2' is 0x7FFFFFFF, while I'd expect to get '2'. The problem is two-fold. First, the algorithm runs topological sort on the graph, and process the vertices in topological order -- which include the '3' vertex. That vertex is not reachable from '0', so it should not be included in the search at all. The second problem is that the distance to that vertex is set to -inf. When combining that distance with edge weight, due to a bug we get +inf. Here's the code: template <class T> struct closed_plus { // std::abs just isn't portable :( template <class X> inline X my_abs(const X& x) const { return x < 0 ? -x : x; } T operator()(const T& a, const T& b) const { using namespace std; T inf = (numeric_limits<T>::max)(); if (b > 0 && my_abs(inf - a) < b) return inf; return a + b; } }; When 'a' is -inf (as is for '3') inf - a overflows and gives -1, and when b is greater than 1, "inf" is returned. I think that the right solution is to change the algorithm so that it does not traverse the vertices not reachable from the start one. Besides fixing my problem, this will also speed up the algorithm. For example, if you have a forest and call dag_shortest_path on the root of just one tree, the algorithm will travese all trees, setting pretty useless values for all of them. I would like to commit the attached patch. All tests still pass on gcc when it's applied. Comments? - Volodya

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[spirit] documentation typo correction
by Jurko Gospodneti� 11 Oct '04

11 Oct '04

Hi In 'http://www.boost.org/libs/spirit/doc/functional.html' 'It is obvious that the authors of STL knows and practices FP.' should read 'It is obvious that the authors of STL know and practice FP'. HTH, Jurko

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Re: [boost] Re: [review] Formal review of the Smart Container library
by brangdon＠cix.compulink.co.uk 10 Oct '04

10 Oct '04

In-Reply-To: <ck8rf2$njl$1(a)sea.gmane.org> nesotto(a)cs.auc.dk (Thorsten Ottosen) wrote (abridged): > At some point it was discussed to have a new policy that decided the > indirection of the reference type. I feel the kinds of container are so different that it isn't appropriate to have a user-level policy which turns one into the other. It might make sense for them to share some common implementation, though. > It create much attention. Indeed. My biggest problem was understanding what the library was, other than a grab-bag of features. The access syntax, for example - I sometimes felt it was a stand alone feature - that it would make just as much sense to have a vector<shared_ptr<T> > or vector<T*> that used the v.begin()->method() syntax, rather than something which flowed out of the specific intent of ptr_vector<T>. I suppose a policy approach might be appropriate if the same policy could be applied to all 3 kinds of vector. However, I am not keen on having 2 syntaxes for doing the same thing in the first place. I'm happy to use pointer syntax for things which are pointers. > smart in the same way smart pointers are smart. It should give the > impression of exception-safety and resource ownership. "Smart" suggests neither of those things to me. > | I am bothered by the libraries interaction with std algorithms. For > | example, std::remove_if<> doesn't work with the container's iterators. > | That makes it, at best, a low-level library that needs to be managed > | carefully. > > Ok, what do you suggest we do instead? I don't know. > | The present library claims performance benefits, but if I need those > | I'd write my own wrapper for vector<T *> which did exactly what I > | needed and no more. > > Could you enumerate what exactly you need and maybe tell why > if a library suported more than you needed, but you didn't use that > extra stuff, it would still be a bad thing? Exactly what I need depends on circumstances. For example, I don't always need to let client code enumerate the container's contents. A container which allow that would need to be wrapped by a class which hid those members, because I don't like my classes to publish more interface than they need to. > Would an unindirected interface be enough? > (eg, you can determine to disable cloning etc). I'm not sure what you mean. > Did you ever forget to implement a wrapper function > with the right exception-safety? I don't believe I've ever had a problem in that area. -- Dave Harris, Nottingham, UK

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Nonconforming filenames in "libs/serialization"
by Aleksey Gurtovoy 10 Oct '04

10 Oct '04

Robert, According to http://tinyurl.com/5abnh, there are still a few nonconforming filenames in the serialization library that need to be fixed: libs/serialization/test/test_polymorphic_archive_data.hpp: filename > 31 chars libs/serialization/vc6ide/demo_portable_binary_archive.dsp: filename > 31 chars libs/serialization/vc7ide/test_derived_class_ptr..vcproj: filename contains more than one dot character ('.') libs/serialization/vc7ide/test_level_class_info_load.vcproj: filename > 31 chars libs/serialization/vc7ide/test_multiplel_ptrs..vcproj: filename contains more than one dot character ('.') Could you please take care of these? TIA, -- Aleksey Gurtovoy MetaCommunications Engineering

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Boost 1_31 - Problem with Lambda, UnNamed namespaces VC7.1
by Brian Braatz 10 Oct '04

10 Oct '04

I have searched the list archive and have not found anything on this subject. I have what looks like to be an issue with MSVC7.1 and unnamed namespaces (the _1 _2 and _3 are in unnamed namespaces in boost::lambda) See below: #include <boost/bind.hpp> #include <boost/Lambda/lambda.hpp> // adding my code to the boost::lambda namespace // below works fine namespace boost { namespace lambda { void MyFunction() { using namespace std; list<int> v; v.push_back(1); v.push_back(2); v.push_back(3); v.push_back(4); v.push_back(5); // Line below works for_each(v.begin(), v.end(), std::cout << _1 << ' '); } } } // Now global namespace void MyFunction() { using namespace std; using namespace boost; using namespace boost::lambda; list<int> v; v.push_back(1); v.push_back(2); v.push_back(3); v.push_back(4); v.push_back(5); // Line below fails with a "error C2872: '_1' : ambiguous symbol" for_each(v.begin(), v.end(), std::cout << _1 << ' '); // This line DOES work for_each(v.begin(), v.end(), std::cout << boost::lambda::_1 << ' '); } Has anyone else run into this? Also- I do not have the current CVS tree handy (I am using 1.31), is this a problem on 1.32? If it is workedaround in some fashion, I can just qualify every _1 and _2 until 1.32 comes out. Thanks for any help or suggestions Brian Braatz

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Re: MPL - mpl::sequence to std::sequence
by Jaap Suter 10 Oct '04

10 Oct '04

>Yeah, I guess Aleksey and Dave have been busy with >the forthcoming MPL book, but as I understand >from list postings, the MPL docs will be updated in >Boost 1.32, and mpl::for_each is one of the more useful >components. Since it's not documented, I learned how it >works from Aleksey. The following works with your code: Thanks! A lot better than my code :).

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RE: [boost] Re: Boost 1_31 - Problem with Lambda, UnNamed namespaces VC7.1
by Brian Braatz 10 Oct '04

10 Oct '04

> "Brian Braatz" <brianb(a)rmtg.com> writes: > > > I have searched the list archive and have not found anything on this > > subject. > > > > I have what looks like to be an issue with MSVC7.1 and unnamed > > namespaces > > (the _1 _2 and _3 are in unnamed namespaces in boost::lambda) > David Abrahams Writes: > Don't you mean in Boost.Bind? [Brian Braatz] Yes, sorry, my mistake.

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[Boost-bugs] [ boost-Bugs-1043616 ] boost::rational documentation typos(?)
by SourceForge.net 10 Oct '04

10 Oct '04

Bugs item #1043616, was opened at 2004-10-09 08:53 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=1043616&group_… Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: boost::rational documentation typos(?) Initial Comment: <http://www.boost.org/libs/rational/ rational.html#Integer%20Type%20Requirements> states: "I must be an integer-like type, that is the following expressions must be valid for any two values n and m of type I, with the "expected" semantics. [...] n / m (must truncate, and n/m must be positive if n and m are positive)" I doubt that that is what boost::rational requires. int n = 1; int m = 3; int n_over_m = n/m; if( n_over_m > 0) { std::cout << "all OK\n"; } else { std::cout << "Can't use 'int' as base type for boost::rational\n"; } <http://www.boost.org/libs/rational/rational.html#Constructors> states: "Rationals can be constructed from a pair (numerator, denominator) of integers, or a single integer" I think that the documentation should read: "Rationals can be constructed from a pair (numerator, denominator) of I's, or a single I" ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1043616&group_… ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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[Boost-bugs] [ boost-Bugs-1043942 ] boost::serialization - strings with '&' character included
by SourceForge.net 10 Oct '04

10 Oct '04

Bugs item #1043942, was opened at 2004-10-10 04:06 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=1043942&group_… Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: Nobody/Anonymous (nobody) Assigned to: Nobody/Anonymous (nobody) Summary: boost::serialization - strings with '&' character included Initial Comment: The issue is related to xml serialization only. I am trying to serialize strings with & character included. When I am trying to deserialize such a string, everything after '&' just disappeared. Also I noticed that serializer doesn't convert '&' to xml entity '&'. I guess it should. However it converts from amp entity when deserializing. Even if I convert '&' to xml entity manually, the problem still occur. As I found debugging the source code, the problem happens because of wrong spirit rule in basic_xml_grammar.ipp file: CharData = (*(anychar_p - chset_p(L"&<"))) [ append_string< StringType, BOOST_DEDUCED_TYPENAME std::basic_string<CharType>::const_iterator >(rv.contents) ] ; when I deleted '&' I was able to deserialize strings with '&' at least. I do not know how it can affect other aspects of deserialization. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=107586&aid=1043942&group_… ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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true64cxx regresion reports
by Fernando Cacciola 10 Oct '04

10 Oct '04

Hi, While adding failure markups, I noticed that the Optional library is shown as failing with true64cxx. However, looking at the error I can see that it is using an older version of the library (one which indeed is defective) I'm also seeing similar results for this toolset and the Numeric Conversion Library Can anyone fix this? TIA Fernando Cacciola SciSoft

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