October 2003 - Boost-users - lists.stage.boost.cppalliance.org

boost::shared_ptr and stl algorithms
by Bill Eidson 15 Apr '05

15 Apr '05

std::vector< boost::shared_ptr<T> > TVec; I want to write a function object to run std::for_each. to do somework against members of T and accumulate results in functor. My attempts have failed in VC7 with memory errors in my operator() method. struct fo { bool operator()( boost::shared_ptr<T>& t ) { return true; } }; Thanks in advance bille

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Will libraries built on WinNT run on Win98? (MinGW)
by Reed Hedges 31 Mar '05

31 Mar '05

I know that Win98 is not really supported, but is there any chance that libraries (specifically thread and regex) that were build on WinNT using MinGW work on Win98 (in MinGW)? My guess is no, but has anyone tried it? thanks reed

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BGL and reversing / moving edges
by joshrose 17 Dec '03

17 Dec '03

G'day, I was hoping someone might be able to tell me if they've run into any situations using BGL where they needed to move (or reverse (i.e. flip the source and target)) an edge within a graph implemented as an adjacency_list. I'm working on an implementation of an algorithm for max. weight bipartite matching ("the assignment problem"), and one of the assumptions in the algorithm is that non-matched edges are directed from one subgraph, A, to the other subgraph, B, and matched edges are directed the other way. Over the course of growing the matching, a simple way to add and remove edges from the candidate set is just to reverse the edge, thus the need for some way to reverse the edge within BGL. I don't think I can just remove and then re-add the edge in the other direction, primarily because doing so will (I believe) invalidate any edge_descriptors referring to that edge. In particular, there are property maps keeping track of the weight of edges, the predecessors of certain nodes, etc. that use edge descriptors as keys. I've spent a fair bit of time reading the documentation and looking through the implementation of adjacency_lists (incl. edge_list_impl), and I'm not really sure of a way to either move an edge directly within a graph, or even to create a new edge from another s.t. they have the same edge_descriptor (in general a bad thing, probably). Anyone have any thoughts on this? Thanks, -Josh

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Boost Software License: redistribute modified works?
by Steve M. Robbins 16 Dec '03

16 Dec '03

Hi, I've a question for the drafters of the Boost Software License - Version 1.0 - August 17th, 2003. Put yourself in the position of someone who wants to redistribute a modified version of Boost. For example, the linux distributors like Debian. The license begins with the permission grant: Permission is hereby granted, free of charge, to any person or organization obtaining a copy of the software and accompanying documentation covered by this license (the "Software") to use, reproduce, display, distribute, execute, and transmit the Software, and to prepare derivative works of the Software, and to permit third-parties to whom the Software is furnished to do so, all subject to the following: [... a restriction and a disclaimer paragraph ...] As I read this, "the Software" means "the unmodified tar or zip file obtained from boost.org". Is that correct? I'm permitted to "prepare derivative works of the Software", but the license doesn't specify what I may do with my derivative works. Clearly, I may distribute "the Software", but may I distribute the derivative work? Some licenses (e.g. the BSD and the GPL) make it clear that the terms apply to both the software and to derivative works. Shouldn't the boost license do likewise? -Steve

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[BGL] Using default_dfs_visitor on a graph with std::list as the vertex type
by sashan 25 Nov '03

25 Nov '03

I'm trying to use a vistitor class on a graph I have defined. The visitor class is very simple and inherits from default_dfs_visitor: class OpenGLVisitor : public boost::default_dfs_visitor { public: OpenGLVisitor(void); virtual ~OpenGLVisitor(void); }; My graph type is: typedef adjacency_list < vecS, listS, directedS > graph_t; The code to perform a dfs on the graph is as follows: graph_t g; depth_first_search(g, visitor(OGLVisitor)); However I get the compiler error (see attachment). If I change the typedef to typedef adjacency_list < vecS, vecS, directedS > graph_t; then there is no error. This seems odd since it should also work when the vertices of the graph use the std::list as their container class. I'm using VC++7.1.

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travelling salesman for BGL ?
by Philippe Guglielmetti 13 Nov '03

13 Nov '03

I'm looking for a free "travelling salesman problem" solver. Does anyone know if something exists for the Boost Graph Library ? I found nothing in the book... Is anybody interested in porting existing code, for example http://www.math.princeton.edu/tsp/concorde.html on BGL ? -- Philippe Guglielmetti - www.dynabits.com

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Is threads CodeWarrior project broken?
by Steve Folly 04 Nov '03

04 Nov '03

Hi, I'm trying to build the threads library on Codewarrior with the .mcp project supplied in libs/thread/build/ (using CW9, OS X 10.2.8), but Codewarrior says the file is not a project file. Is it broken? I could probably recreate it, but I'm not sure about about what source files to include for the Mac - there's all the extra stuff under src/mac/ and then what about the src/mac/msl_replacements/ stuff? Any help gratefully received. I'd like to do a multi-target project for Mac and Win32; tips for source files for Win32 would be helpful too. Thanks. Steve.

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RE: [Boost-users] [BLL] How to search in a list for an object comparing a data member?
by Ben Hutchings 01 Nov '03

01 Nov '03

Gianluca Silvestri <gianluca.silvestri(a)maior.it> wrote: > Hi all, > What I want to achieve is a code similar to this: > > struct Foo { int fDataMember;} > > int main() > { > std::vector<Foo> foos; > Foo fo; > std::find_if(foos.begin(), foos.end(), _1->fDataMember == > fo.fDataMember); //<-- won't compile; } Well, apart from the missing semi-colon, missing includes and missing closing brace, I imagine you're having trouble with "_1->fDataMember". This is a documented limitation of the lambda library - there is no way to defer lookup of member names (overloading -> just changes the type and value of the pointer used) so member access can't be done on a placeholder. > I know I could use a functor object but this is just an example for a > more general need. Sorry, you'll have to define functors. These template functor classes might be useful: template<typename C, typename V, const V C::* P> struct lookup_member_const { const V & operator()(const C & c) const { return c.*P; } }; template<typename C, typename V, V C::* P> struct lookup_member { V & operator()(C & c) const { return c.*P; } }; Mind you, there might be similar things in Boost already.

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Build+Install+/Zc:wchar_t in Visual studio builds
by John Maddock 01 Nov '03

01 Nov '03

Guys, Rene's new Install code is working very well for me now, but I have a question about how we're building with Visual Studio .NET. Currently the vc7 and vc7.1 toolsets turn on /Zc:wchar_t unconditionally when building, however this is not the default option in current versions of the IDE, and of course the two options produce binary-incompatible libraries (at least as far as regex is concerned). How should we handle this? At the very least I would like to see a bjam option to turn off /Zc:wchar_t, but how should we be building the libraries by default: turning native wchar_t support on is the standards conforming way, but not currently the default Visual Studio way, or the way many third party libraries (like ICU for example) are built. Does anyone know how this option interacts with MFC/ATL/VisualForms etc? We could of course create a new build variant to handle this, but with 8 regex lib/dll variants already I'm not keen to add another 8 (apart from anything else testing already takes too long). I'm cross posting this to the Boost.users group as well, since whatever resolution we take will affect them the most :-) Thanks, John.

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[newbie] creating a (complex?) C++ wrapper around a C function call...
by Jason House 31 Oct '03

31 Oct '03

I want to create a wrapper function template <class foo> op_pk_fd_set_class(packet *packet, int index, foo &value, int simulated_bits); around the following function... (in OPNET) op_pk_fd_set( packet* pkptr, // same as in wrapper int index, // same as in wrapper int some_constant, //OPC_TYPE_STRUCT void* value, int simulated_bits, // same as in wrapper void* (*copy_proc)(void* obj_to_copy,int alloc_size), void (dealloc_proc*)(void *obj), int alloc_size); I believe dealloc_proc can just be a function pointer to the destructor. I could very well be mistaken, but I believe that a normal constructor takes only one parameter. I also think alloc_size should be sizeof(foo). I do not know how to obtain function pointers for constructor and deconstructor member functions. Any assistance I could get would be appreciated.

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