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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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[multi-index] No constructor that takes allocator only
by Michael Fawcett 30 Jan '08

30 Jan '08

Joaquín, thanks so much for a wonderful library. I was wondering why there is no constructor that simply takes an allocator. This would make multi_index behave more like STD Library containers, which would aid me in allowing flexible storage options for generic algorithms. Is there a technical hurdle that makes this difficult to do? You currently provide: explicit multi_index_container( const ctor_args_list& args_list=ctor_args_list(), const allocator_type& al=allocator_type()); template<typename InputIterator> multi_index_container( InputIterator first,InputIterator last, const ctor_args_list& args_list=ctor_args_list(), const allocator_type& al=allocator_type()); Is it possible to also provide: explicit multi_index_container( const allocator_type& al=allocator_type()); ? Thanks again! --Michael Fawcett

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Boost Format: format strings and character types
by Daniel James 30 Jan '08

30 Jan '08

The documentation states that the same format string used with printf and boost::format should result in the same output in "almost all cases". My colleagues and I have found, though, that when a %d descriptor is used to print a char variable the result is as though a %c descriptor had been used -- printf and boost::format don't produce the same result. That is: int ii(42); char cc(42); printf( "Using printf: ii=%d, cc=%d\n", ii, cc ); cout << boost::format( "Using boost::format: ii=%d, cc=%d" ) % ii % cc << endl; Produces: Using printf: ii=42, cc=42 Using boost::format: ii=42, cc=* So, it seems that boost::format deduces the format to be used for outputting cc from its type and ignores the format explicitly requested in the format. Is this working as intended? If so the documentation seems to me to be misleading. I also note that: cout << boost::format( "As chars: ii=%c, cc=%c" ) % ii % cc << endl; Produces: As chars: ii=4, cc=* That is: the %c descriptor causes the value of ii (42) to be truncated to a single char. Also something of a surprise. My tests were carried out using boost 1.34.1 and Visual Studio 2005 on Windows. Cheers, Daniel.

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[FileSystem] Linker Error on OS X with ICC - common symbols not allowed with MH_DYLIB
by Mike Jackson 30 Jan '08

30 Jan '08

I am trying to compile some code into a dynamic library and I am getting the following linker errors: Linking CXX shared library Bin/libLibTest.dylib xilibtool: executing 'libtool' ld: common symbols not allowed with MH_DYLIB output format with the - multi_module option CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem12initial_pathINS0_10basic_pathISbIwSt11char_tr aitsIwESaIwEENS0_12wpath_traitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem12initial_pathINS0_10basic_pathISsNS0_11path_tr aitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISbIwSt 11char_traitsIwESaIwEENS0_12wpath_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZGVZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISsNS0_ 11path_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem12initial_pathINS0_10basic_pathISbIwSt11char_trai tsIwESaIwEENS0_12wpath_traitsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem12initial_pathINS0_10basic_pathISsNS0_11path_trai tsEEEEERKT_vE9init_path (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISbIwSt11 char_traitsIwESaIwEENS0_12wpath_traitsEEEEEmRKT_E7end_itr (size 16) CMakeFiles/LibTest.dir/LibTest.o definition of common __ZZN5boost10filesystem6detail14remove_all_auxINS0_10basic_pathISsNS0_11 path_traitsEEEEEmRKT_E7end_itr (size 16) libtool: internal link edit command failed make[2]: *** [Bin/libLibTest.dylib] Error 1 make[1]: *** [CMakeFiles/LibTest.dir/all] Error 2 make: *** [all] Err This is on OS X 10.4.11 with Intel C++ compiler version 10.1.007. Maybe I am not using the boost file_system library correctly? A simple reproducible case is to just try to create a library containing any code that includes boost/filesystem/operations.hpp. The same code works on gcc on OS X 10.4.11 (Xcode 2.5 tool set) -- Mike Jackson imikejackson & gmail * com

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