January 2008 - Boost-users - lists.preview.boost.org

releasing code under the BSL
by Manfred Doudar 31 Jan '08

31 Jan '08

Hello all, Hoping some one might offer some guidance... (somewhat off-topic, appologies). I've developed a generic DAG library in-house and seeking to place it under the BSL, and would even go as far as a Boost review if people here want such a thing (that's the intention after all). Now, I have obtained authorization from my organization's management and their legal representatives for the software release (yippee!). However, an email trail of approvals, while legal tells me is satisfactory, I would much rather a written approval on company a letter-head. IP Counsel of the organization I work for just said I ought to draft the letter myself and just have the Lab Director sign it (, consistent with the approval already granted .. ie. "Ok to release the work under the BSL"). My question is, what exactly ought to be the wording of such a letter? All help appreciated, and again apologies if it is too far removed from Boost.users NG business. If I ought to take this question elsewhere, please do let me know. Cheers, -- Manfred Doudar - Principal Research Engineer (Software) National ICT Australia - Canberra Research Lab | www.nicta.com.au Research School of Information Sciences and Engineering (RSISE) The Australian National University - Canberra, ACT 0200 AUSTRALIA

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[boost any] casting problems (BUG?)
by Ovanes Markarian 31 Jan '08

31 Jan '08

Hello *, I would like to ask the developers of boost::any if the ctor template in boost::any template<typename ValueType> any(const ValueType & value) : content(new holder<ValueType>(value)) { } is intentionally not marked as explicit. Today using boost::any_cast and with a std::map (mapping of some id to boost::any) iterator I was wondering why I got an exception when I found a correct any instance. My code looked like: map_type::const_iterator iter = map.find(Key); if(map.end()!=iter) return boost::any_cast<SomeResultType const&>(*iter); Unforturenately, I forgot that map iterator references a pair<KeyType, ValueType>. This cast caused the compiler to implicitly create a new const any type containing the dereferenced pair and throw an exception that my expected result type was wrong. I don't know which design rationale was intended when this ctor was not marked as explicit or if it is a bug. With Kind Regards, Ovanes BTW, I use boost 1.34.1 and vc 7.1.

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Re: [Boost-users] Boost Thread: condition.wait()
by Kesseli Pascal 31 Jan '08

31 Jan '08

Hey Ya Thanks for the quick reply. Well, it would be more complicated in the way that the only condition that would keep in the loop would be the number of threads already arrived on this condition (numberOfThreadsReady). As soon as all threads have arrived, this number is set back to zero, which would keep the threads waiting if they re-checked this condition. But I found out that Boost supports a much more suitable solution for this problem, namely the barrier class. And, concerning the use of a barrier, I trust I am not mistaken that there is no loop needed when calling barrier.wait(), or is there :) ? If so, that would call my complete understanding of the barrier mechanism into question :) . Thanks again & greeetz Pascal "Vladimir Prus" <ghost(a)cs.msu.su> schrieb im Newsbeitrag news:<fnp5p1$cce$1(a)ger.gmane.org>... > Kesseli Pascal wrote: > > > Hi everyone > > > > Recently I was trying to synchronize one of my functions using the > > following code: > > > > // write own data to shared vector... > > // ... > > if (++numberOfReadyThreads < numberOfInvolvedThreads) { > > allChargingDataReady.wait(lock); > > return; > > } > > numberOfReadyThreads = 0; // Only the last thread enters this section. > > // write data to file... > > allChargingDataReady.singal_all(); > > > > The idea is that all threads submit their data using this function and > > then wait before reading in the next set of data until all threads have > > submitted their data. The last thread to submit his data is the one who > > has to write the collected data to a file. > > > > Using this structure, I find it very simple to realize this behavior. > > However, I know from programming with Java that the VM there sometimes > > awakens one's threads without any reason, which means that I would have to > > realize my condition like this instead: > > > > > > // ... > > while(numberOfReadyThreads < numberOfInvolvedThreads) { > > allChargingDataReady.wait(lock); > > } > > // ... > > > > Implementing the same behavior using this snippet is much more complicated > > though and I would rather avoid it if possible. > > Why is it more complicated? > > > And that leads us right > > away to my question: > > > > Is the while()-workaround using Boost & C++ needed as well as in Java? Or > > can I use the much simpler if()-version? > > As docs say, you need to test your condition in a loop in Boost.Threads. > This is not a particular property of Java or Boost.Threads -- that's how > POSIX threads work. (Windows don't have native condition, and I have much > clue how conditions are simulated on windows and whether window Event thing > has similar behaviour). > > - Volodya No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.19.16/1251 - Release Date: 30.01.2008 09:29

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Flyweight
by Martin Fisher 31 Jan '08

31 Jan '08

My test program was as follows: [Code] // fly.cpp : main project file. #include "stdafx.h" #include <string> #include <iostream> #include <vector> #include <fstream> #include <iterator> #include <algorithm> #include <boost/progress.hpp> #include <boost/flyweight.hpp> using namespace std; vector<boost::flyweight<string> > vec; //vector<string> vec; struct Insert { void operator()(string s) { vec.push_back(boost::flyweight<string>(s)); //vec.push_back(s); } }; void Test() { fstream f("d:\\bible12.txt", ios_base::in); // A large text file! { boost::progress_timer t; for_each(istream_iterator<string>(f), istream_iterator<string>(), Insert()); } } int main(int argc, char* argv[]) { Test(); cout << vec.size() << endl; getchar(); copy(vec.begin(), vec.begin() + 200, ostream_iterator<string, char>(cout, " ")); getchar(); return 0; } [/Code] Using the boost_1_35_0 svn library download and Visual C++ 2008 Express edition. Originally compiled as a CLR program. Recompiling using native Win32 still gives a crash during program termination - in atomic_count_win32.hpp in operator-- (BOOST_INTERLOCKED_DECREMENT) Unhandled exception at 0x010752b9 in fly2.exe: 0xC0000005: Access violation writing location 0x00779040. There is still the anomaly of release version being slower than debug. Compiled as release - the exception occurs in xmemory in _Destroy_range. I'll experiment using set_factory in Borland - although I have largely abandoned it's use, just can't compile enough of Boost to be useful now... Martin

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[boost-users] [general question].
by chun ping wang 31 Jan '08

31 Jan '08

Hey guys does anyone know any good template engine for c++. I mean not like c++ template programming but web template engine that are easy to use, works on multiple platform, etc... Example Smarty <http://www.smarty.net/> for php. Velocity <http://velocity.apache.org/> for java. Cheetah <http://www.cheetahtemplate.org/> for python. Is their an ongoing project for boost to do this? Thanks, Chun Ping Wang.

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BGL - changing internal values of a graph
by Renato Golin 31 Jan '08

31 Jan '08

Hi, I'm trying to write a simple graph: // Link and Edge types struct Link { std::string name; }; struct Edge { long count; }; // directed graph typedef boost::adjacency_list < boost::vecS, boost::vecS, boost::directedS, Link, Edge > graph_t; // Vertex and Edge descriptors typedef boost::graph_traits < graph_t >::vertex_descriptor link_d; typedef boost::graph_traits < graph_t >::edge_descriptor edge_d; // Map with all vertexes and links (deduplicate) typedef std::map < std::string, link_d > link_map_t; And my method to add a vertex (which is working well) is: link_d Chain::addVertex (string& name) { link_map_t::iterator pos; link_d descriptor; Link link; bool inserted; // Insert into map boost::tie(pos, inserted) = links.insert(make_pair(name, link_d())); // Insert into graph (or get descriptor) if (inserted) { link.name = name; descriptor = add_vertex(link, graph); pos->second = descriptor; cerr << "Added new vertex: " << graph[descriptor].name << endl; } else { descriptor = pos->second; cerr << "Reused old vertex: " << graph[descriptor].name << endl; } return descriptor; } And my method to connect the edges (which is not working) is: void Chain::addConnection (string subject, string object) { link_d sub, obj; edge_d pred; Edge e; bool inserted, found; // Add vertices sub = addVertex(subject); obj = addVertex(object); // Connect through predicate and increment counter boost::tie(pred, found) = edge (sub, obj, graph); if (found) { e = graph[pred]; cerr << "Old, pred: " << pred << " count: " << e.count << endl; e.count++; } else { e.count = 1; } boost::tie(pred, inserted) = add_edge(sub, obj, e, graph); e = graph[pred]; // Print to see if it was correct cerr << "New, pred: " << pred << " count: " << e.count << "\n" << endl; } By reading a text line "ABABAB." and taking letter by letter and inserting into sub and obj (A,B), (B,A) ... I have the following output: line [ABABAB.] Added new vertex: first Added new vertex: A New, pred: (0,1) count: 1 Reused old vertex: A Added new vertex: B New, pred: (1,2) count: 1 Reused old vertex: B Reused old vertex: A New, pred: (2,1) count: 1 Reused old vertex: A Reused old vertex: B Old, pred: (1,2) count: 1 New, pred: (1,2) count: 2 Reused old vertex: B Reused old vertex: A Old, pred: (2,1) count: 1 New, pred: (2,1) count: 2 Reused old vertex: A Reused old vertex: B Old, pred: (1,2) count: 1 New, pred: (1,2) count: 2 Reused old vertex: B Added new vertex: . New, pred: (2,3) count: 1 Reused old vertex: . Added new vertex: last New, pred: (3,4) count: 1 The creation and reuse of vertices is working pretty well as you can see but the edge, even when reused doesn't have its value updated on a second time. It may be a very stupid problem (not even in BGL) but can you help me find out what's going on? Basically, the following part works while inside the function: if (found) { e = graph[pred]; cerr << "Old, pred: " << pred << " count: " << e.count << endl; e.count++; } I'm getting it again from the graph in order to assure it changed: boost::tie(pred, inserted) = add_edge(sub, obj, e, graph); e = graph[pred]; And even when using a new variable: boost::tie(pred, inserted) = add_edge(sub, obj, e, graph); Edge f; f = graph[pred]; My cerr still produces the correct value. But when I get it a few iterations later the value is 1 again. What's going on? Or better, how to change the value of the structure inside the graph? thanks, --renato

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Re: [Boost-users] [boost] [review] Fast track review of Boost.Utility/Singleton - rejected for now
by John Torjo 31 Jan '08

31 Jan '08

Hi Tobias, > >> I would like to see this into Boost, so I hope Tobias will update the >> library, given all this feedback, and I would suggest another review in >> 2-3 months. I'd like to be the review manager then as well, if Tobias >> will still want me. >> > > I've no objections to the review manager part but I'm afraid that I'll > have to put this one on hold, as I don't have enough time nor energy for > a redesign in the immediate future. Right now, I can't promise anything, > so I'm fine with "just reject" for now :-). > > > Ok. Please let me know when you're ready to revive it. Best, John > Regards, > Tobias > > _______________________________________________ > Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost > > -- http://John.Torjo.com -- C++ expert ... call me only if you want things done right

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[flyweight] Review
by Neil Hunt 30 Jan '08

30 Jan '08

* What is your evaluation of the design? I like ability for the drop in replacement of const T (with assignability). It makes it easy to test whether it makes a big difference in run time scenarios, before committing to its use. I liked the policy based interface. * What is your evaluation of the implementation? I had a small hunt around the code and liked the modularity of it. A friend of mine railed against the default use of a static factory. He would prefer, by default, to control the lifetime of the factory, but that would make it harder for "drop in" usage, and there is the flexibility of overriding the holder class. * What is your evaluation of the documentation? I didn't read it all closely, but I certainly understood what the library was for and how to use it after viewing the docs. Of course, real world mileage will vary, but some performance indicators or at least discussion of the tradeoff of extra hashing vs reduced dynamic allocations would be useful, as well as any other performance impacts (how big should the data set be before using it, what percentage of unique values makes it worthwhile). * What is your evaluation of the potential usefulness of the library? Useful to have available. Unless there is a no brainer scenario, it seems that real world testing on live data will be needed to evaluate it's value in any given scenario? * Did you try to use the library? With what compiler? Did you have any problems? I didn't try the library, since I am not using 1.35. But I am keen to use it when 1.35 is released. * How much effort did you put into your evaluation? A moderate investigation. * Are you knowledgeable about the problem domain? No experience making an implementation, but knowledgable about the problem. * Do you think the library should be accepted as a Boost library? Yes Neil Hunt

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[boost::any] any chance that someone will take a look at my previous post?
by Ovanes Markarian 30 Jan '08

30 Jan '08

Hi! I posted this post http://lists.boost.org/boost-users/2008/01/33607.php 2 days ago. Can someone of the developers give a statement on this issue? Many thanks, Ovanes

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Flyweight
by Martin Fisher 30 Jan '08

30 Jan '08

/* boost::flyweights::flyweight<string>::initializer init; vector<boost::flyweights::flyweight<string> > vec; */ Thanks Joaqu?n. That fixes all. I'd noticed a bit in the doc about initialisation - just my attempt to write a minimal test case got the better of me. Release is still slower than debug under MS - 60 cf 56s with my computer cranked up to full tilt.. Put that down to some dubious MS code generation. For comparison the example program took 927s for hashed factory when compiled as debug and 1365s when compiled as release (ok I didn't repeat the tests!) I'll have to get a smaller test file :-) Best wishes Martin

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