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

Help me pay the piper?
by dick.bridges＠tais.com 08 May '02

08 May '02

Now that I've used all this swell stuph, it's time to pay the piper: turn it over to QC and get it into "The Build". Unfortunately the QC people would like some instructions that describe which version of boost-build I'm using; how to install it; which version of the libs I'm using; etc. <some background> It's been a couple of months since I started with the boost libs, and I don't remember all the gyrations I went through to get it working and I'm POSITIVE I did a LOT more than is required. I remember that, after downloading and extracting boost_1_27_0.tar.gz, I had to get the current version from CVS before I could get a clean compile. (I tried turning over copies of my disk drives to them but it turns out that is not considered acceptable documentation. %>[ ) I've been following the jamboost and Boost-Users mailing lists so I know there've been quite a few changes - especially to boost-build. After building a "clean" testbed machine, I started by downloading boost-build.win.zip and following the instructions in the readme.html. Well, that didn't work. I can do a hand job on the path but I'm not sure what environment variables are actually required. Current plan is to pull the library source directly from CVS. Problem is, I don't know what version to tell QC I'm using and, unless all the folks at boost.org would agree not to add anything to CVS for a while, I SURE can't tell them how to re-create what I did. ;) </some background> I can always take what I've got; check it in and call it a day but that's not the path to getting boost integrated into the development environment around here. (Hey, I'm trying to be an evangelist here.) Anyone by any chance working on some updated instructions and/or docs that maybe aren't ready for prime time but would be willing to share? TIA PS: Current target systems are Win2000, SP2 and Visual C++ 6.0, SP5 and vanilla Red Had Linux 7.2.

2 1

voronoi diagram and BGL
by Louis Lavery 08 May '02

08 May '02

Hi, Is it possible to order the edges of a vertex of a boost graph? >From what I can glean from the BGL documentation, I guess the answer will be "No, but may be some time in the future". I so, how soon in the future? Thanks, Louis.

5 5

Solaris jam build
by cs_jritchie 08 May '02

08 May '02

I am receiving the following on a Solaris system when using: jam -sBOOST_ROOT=. -sTOOLS=gcc status/Jamfile:53: in failed-test-file warning: unknown rule FAIL_EXPECTED status/Jamfile:100: in fail-to-build ./tools/build/boost-base.jam:1407: in subvariant-target ./tools/build/boost-base.jam:1448: in main-target ./tools/build/boost-base.jam:1065: in declare-local-target status/Jamfile:35: in boost-test status/Jamfile:119: in compile-fail status/Jamfile:368: in SubInclude ./tools/build/allyourbase.jam:1141: in subinclude Jamfile:5: in module scope {...above repeated many times...} Unable to load Boost.Build, it seems that the build system files were located, but the build system is not defined. Attempted to use, as the bootstrap, this file: ./tools/build/boost-build.jam. This means that even though that file was loaded it either failed to directly load the build system files, or it failed to specify where to find and load the files by calling the 'build-system [path] ;' rule. Please consult the documentation at 'http://www.boost.org'. What am I doing wrong? Any help is appreciated.

2 4

Re: Problems building Python lib
by pendrildurham 08 May '02

08 May '02

Sorry -- Newbie here -- I don't know exactly what the 'latest CVS state' is or how to get it. I have been trying to build boost-python on Windows95 with MSVC++6. I have boost 1.27 and activestate python 2.2.1 build 222. I can get it to compile but the link fails. Here is the linker message for the boost-example1: Linking... Creating library Debug/hello.lib and object Debug/hello.exp example1.obj : error LNK2001: unresolved external symbol "bool __cdecl boost::python::handle_exception_impl(class boost::function0<void,struct boost::empty_function_policy,struct boost::empty_function_mixin,int>)" (?handle_exception_impl@python@boos t@@YA_NV?$function0@XUempty_function_policy@boost@@Uempty_function_mix in@2@H@2@@Z) bpl_static.lib(types.obj) : error LNK2001: unresolved external symbol "bool __cdecl boost::python::handle_exception_impl(class boost::function0<void,struct boost::empty_function_policy,struct boost::empty_function_mixin,int>)" (?handle_exception_imp l@python@boost@@YA_NV?$function0@XUempty_function_policy@boost@@Uempty _function_mixin@2@H@2@@Z) bpl_static.lib(extension_class.obj) : error LNK2001: unresolved external symbol "bool __cdecl boost::python::handle_exception_impl(class boost::function0<void,struct boost::empty_function_policy,struct boost::empty_function_mixin,int>)" (?handle_exc eption_impl@python@boost@@YA_NV?$function0@XUempty_function_policy@boo st@@Uempty_function_mixin@2@H@2@@Z) bpl_static.lib(extension_class.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) bpl_static.lib(functions.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) bpl_static.lib(objects.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) example1.obj : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) bpl_static.lib(module_builder.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) bpl_static.lib(init_function.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) bpl_static.lib(classes.obj) : error LNK2001: unresolved external symbol "struct _object * __cdecl boost::python::expect_non_null(struct _object *)" (?expect_non_null@python@boost@@YAPAU_object@@PAU3@@Z) Debug/hello.dll : fatal error LNK1120: 2 unresolved externals Error executing link.exe. hello.dll - 11 error(s), 0 warning(s) Perhaps there is something simple I can do to fix this? Perhaps there is something I need to include in the project to get the link to work? Can anyone help? Thanks --- In Boost-Users@y..., Albrecht Fritzsche <albrecht.fritzsche@t...> wrote: > David Abrahams wrote: > > >1. Get the latest CVS state. Release 1.27 is broken in several ways. > > > Ooops, ok - I will try the CVS version. > > >The library works with Python 2.2.1 > > > Thanks - that's the info I was hoping for :-) > > Ali

2 1

creating a shared_ptr<T> from a weak_ptr<T>
by Toon Knapen 08 May '02

08 May '02

When creating a shared_ptr<T> from a weak_ptr<T>, I want the shared_ptr<T> to use the same count as the shared_ptr the weak_ptr was constructed from. I could create a new shared_ptr, based on the pointer I can get() from the weak_ptr. But in this case, this shared_ptr will keep its own count. Let me fill you in on my use-case. An object creates some big data-structure on request of its clients, taking into account some options specified by the client while making the request. Now I'd like the server-object to keep a weak_ptr to these big data-structure to provide quickly the same result once another client performs an identical request. The server should however not keep a shared_ptr because otherwise all datastructure will stay in memory. And therefor I need to create a shared_ptr from a weak_ptr. thanks, toon

6 7

Re: [Boost-Users] AllExamples.dsw from BGL Errata Web-site
by Lie-Quan Lee 07 May '02

07 May '02

Hi Jon, Thanks to remind me that attachment doesn't work for yahoogroups. I put the file at http://groups.yahoo.com/group/boost/files/BGLVCprojects.tgz Just in case, it is also available at: http://www.osl.iu.edu/~llee/BGLVCprojects.tgz Jeremy Siek will update the file on BGL book errata page. On Tue, 2002-05-07 at 11:43, Jon Kalb wrote: > >Hi Richard, > > > >It looks like the BGLVCprojects.tgz online is corrupted somehow. I > >attached the right file (about 466.1K) in this message. Please extracts > >the contents of the tarball using winzip 8.0 or up. The tarball includes > >the missing workspace file and project files. > > > >Thanks for reporting that problem! > >-- > >Lie-Quan Lee (AKA: Rich Lee) > >Research Associate http://www.osl.iu.edu/~llee > >Computer Science Department llee(a)cs.indiana.edu > >Indiana University at Bloomington 812-855-3608(Office) > > > >[Non-text portions of this message have been removed] > > Rich, > > As you can see from the line inserted by Yahoo! Groups in your > message, Boost-Users is configured to not allow attachments. If you > wouldn't mind uploading the attachment to the group's shared file > area you can send a link to it. Or if you want to send the file to > me, I'll take care of it. > > Thanks. > > -- > Jon Kalb > Kalb(a)LibertySoft.com -- Lie-Quan Lee (AKA: Rich Lee) Research Associate http://www.osl.iu.edu/~llee Computer Science Department llee(a)cs.indiana.edu Indiana University at Bloomington 812-855-3608(Office)

1 0

AllExamples.dsw from BGL Errata Web-site
by loopylozzysdad 07 May '02

07 May '02

Hi, I am still having no luck with this file. In the Boost Graph Library book (Great book!), Errata web page (http://siek.info/bgl.html) it says... "On the accompanying CD, the file \BGL\VC++ Projects\AllExamples.dsw is missing. You can download the missing file from here BGLVCprojects.tgz." When I download it I get a 454K file. When I open it with WinZip winzip tells me there is a single file BGLVCprojects.tgz in it. when it opens that single file it only finds ONE file in that accum_compile_times.dsw size 4639 bytes. this does not make sense fo r a file that started at 454K but I don't seem able to get any more out of it. I am using WinZip 6.2. Another machine with WinZIP 8.0 reports 'Invalid compressed header after 1 entry'. Is anyone else getting this result. If not could you email me a file that works for you? All the best and thanks - Richard Howells

2 1

Association Library?
by rzako23 07 May '02

07 May '02

Are there any generic components in Boost (or elsewhere) for *directly* representing associations between classes? Generalization, composition, aggregation and association are major ideas in the object model. Generalization can be implemented fairly directly in C++ using inheritance. Composition and aggregation can be represented directly in C++ using data members (when the number of parts in each whole is small and fixed), or using STL containers (when the number of parts in each whole is large or variable). But Standard C++ (including the STL) provides no *direct* support for representing associations, i.e., collections of links between objects in two or more classes. (David Papurt makes this point in "Inside the Object Model: The Sensible Use of C++.") For example, the STL does not offer a way to *directly* represent the 1-to-many "Supervises" association from the Manager class to the Employee class. One would like to have links in both directions: forward links forthe employees a manager supervises and a back link to the manager each employee is supervised by. Of course, one could code this all "by hand" using a container of pointers to employees for each manager and a back pointer for each employee. But the implementation details really have little to do with managers and employees and would be pretty much the same for parents and children or teachers and students. Moreover, while not difficult, managing the forward and back links correctly (and in an exception-safe manner) is tedious. It would be nice to have templates that can be instantiated to implement specific associations. In brief, STL containers directly support composition and aggregation but not association. I am new to the Boost library, but was not able to find this capability in Boost. If an association library is available in Boost (or elsewhere), I would be happy to know so. If not, is an association library something that would be worth looking into? Thanks, Rob Zako

11 24

Problems building Python lib
by Albrecht Fritzsche 03 May '02

03 May '02

Hi, since I've read in the documentation "Boost.Python is known to have been tested in the following configurations: Against Python 2.0 using the following compiler/library combinations: MSVC++6sp4 with the native library. ... Against Python 1.5.2 using the following compiler/library: MSVC++6sp4 MSVC++6sp4/STLport 4.0" and since I am using the MSVC++6sp4/STLport 4.0 combination I deinstalled Python 2.2 (for which the build failed) and installed Python 1.5.2. Running G:\Environment\boost_1_27_0>jam -sBOOST_ROOT=. -sTOOLS="msvc-stlport" I get the following errors: don't know how to make <python-library@>python21.lib ...patience... ...patience... ...found 2247 targets... ...using 2 temp targets... ...updating 132 targets... ...can't find 1 target... ...can't make 42 targets... msvc-C++-action libs\python\build\bin\libboost_python_static\msvc-stlport\debug\ runtime-link-dynamic\stlport-iostream-off\stlport-version-4.0\types.obj types.cpp .\boost/python/detail/wrap_python.hpp(24) : fatal error C1083: Include-Datei kann nicht geoeffnet werden: 'patchlevel.h': No such file or directory cl /Zm400 -nologo -GX -c -DBOOST_PYTHON_STATIC_LIB=1 -DBOOST_PYTHON_DYNAMI C_LIB -D__STL_NO_SGI_IOSTREAMS=1 -D__STL_DEBUG=1 -D__STL_DEBUG_UNINITIALIZED=1 /Zi /Od /Ob0 /GX /GR /MDd -I"libs\python\build" -I"." -I"c:/tools/python\inclu de" -I"c:/tools/python\PC" -I"\stlport" -I"D:\PROGRA~1\MICROS~1.0\VC98\include" -Fo"libs\python\build\bin\libboost_python_static\msvc-stlport\debug\runtime-li nk-dynamic\stlport-iostream-off\stlport-version-4.0\types.obj" -Tp"libs\python\ build\../src\types.cpp" ...failed msvc-C++-action libs\python\build\bin\libboost_python_static\msvc-stlp ort\debug\runtime-link-dynamic\stlport-iostream-off\stlport-version-4.0\types.ob j ... msvc-C++-action libs\python\build\bin\libboost_python_static\msvc-stlport\debug\ runtime-link-dynamic\stlport-iostream-off\stlport-version-4.0\classes.obj classes.cpp .\boost/python/detail/wrap_python.hpp(24) : fatal error C1083: Include-Datei kan n nicht geoeffnet werden: 'patchlevel.h': No such file or directory ............ [The obvious translation of this error message is: Cannot open include file 'patchlevel.h'.] What am I doing wrong? By the way, all of the other libs including tests are compiling with Jam without any problems at all. And, as a second quesion, why is there no MSVC++6sp4/STLport 4.0 support for the newer Python versions - by the way, there is already a Python v2.2. Thanks for any hints and help Ali *

5 7

Re: [boost] boost organization and installation
by William E. Kempf 02 May '02

02 May '02

----- Original Message ----- From: "David Abrahams" <david.abrahams(a)rcn.com> > > ----- Original Message ----- > From: "William E. Kempf" <williamkempf(a)hotmail.com> > > OK, let me make this a bit more of an official request. If anyone is > > interested in volunteering for this effort send me a private e-mail. > Once I > > have, let's say at least 5, committed volunteers I'll start the effort > of > > creating and coordinating the needed community. > > I don't know whether you want to count me as a volunteer or not. I'm > willing to handle things from the Boost.Build end at some workable pace. > I don't think I can invest anything in other systems, except at the > integration boundary (e.g. if autotools builds Jam and calls it to build > boost). I'd hope that every developer with a current Boost library would be willing to volunteer to at least help with input here, and possibly to committing to some (minor) changes to procedures and/or code. I'm also glad you're volunteering to help from the Boost.Build end of things. But I won't count you as a volunteer for the actual effort here, since I know how busy you are. What I think we really need are volunteers from the user community, though I won't turn down any current Boost developers who think they have the time and experience to help out here. In any event, since I hope that we get volunteers from the user community, I'm CC:ing this to the Boost Users list. Anyone interested in helping out in this effort should e-mail me privately. Bill Kempf

2 1

RE: [Boost-Users] MPL ?
by Aleksey Gurtovoy 01 May '02

01 May '02

Toon Knapen wrote: > Inside a templated class, I need to provide two different > implementations for > a function based on the compile-time decision > ::boost::is_convertible< value_type,double >::value. > How can I do this using MPL ? 1) A simple way: template< typename T > class my { public: typedef typename T::value_type value_type; void foo() { typedef boost::is_convertible< value_type,double > c; do_foo(mpl::bool_c<c::value>()); } private: void do_foo(mpl::true_c) { /*...*/ } void do_foo(mpl::false_c) { /*...*/ } }; Andrei has written an article that covers this technique - http://www.cuj.com/experts/1810/alexandr.htm. 2) A sophisticated one (becomes more relevant when you have several "foo"'s to handle): template< typename T, typename Derived > struct foo_impl { void foo() { Derived& self = static_cast<Derived&>(*this); // ... } }; template< typename Derived > struct foo_double_impl { void foo() { Derived& self = static_cast<Derived&>(*this); // ... } }; template< typename T > class my : public mpl::select_if< boost::is_convertible< typename T::value_type,double > , foo_impl<T, my> , foo_double_impl<T> >::type { // ... private: friend class foo_impl<T, my>; friend class foo_double_impl<T>; // ... }; HTH, Aleksey

1 0

MPL ?
by Toon Knapen 01 May '02

01 May '02

Inside a templated class, I need to provide two different implementations for a function based on the compile-time decision ::boost::is_convertible< value_type,double >::value. How can I do this using MPL ? thanks, toon

1 0

RE: [Boost-Users] shared_ptr and incomplete types
by bjorn.karlsson＠readsoft.com 01 May '02

01 May '02

> From: Jim Hyslop [mailto:jim.hyslop@leitch.com] > > I notice that the implementation available at boost.org does not allow > the single-argument ctor to be called on an incomplete type, e.g.: [snip] > The documentation on the single-argument ctor, though, does not state > that T must be a complete type. Is the implementation > stricter than the > documentation, or is the documentation incomplete? I believe that the implementation is correct, and that belief is confirmed by the latest documentation in the CVS - T must indeed be a complete type. Another change is the addition of a default constructor, which does not require T to be complete. > I'm writing an article on the smart pointers for the CUJ, and I'd like Cool! ;-) > to know if I can correctly state "The default behavior for > shared_ptr is > to require complete types. You can, however, manage an incomplete type > if you provide a function or function object, which will be > called when > the owned object is destroyed." Since shared_ptr requires a complete type only for a few operations, such as the constructor that you mentioned, and reset(T * p), I'd rephrase to something more explicit, like: "The instantiation of a shared_ptr typically requires a complete type. [etc]". Bjorn Karlsson [Non-text portions of this message have been removed]

2 1

shared_ptr and incomplete types
by Jim Hyslop 01 May '02

01 May '02

The documentation at http://www.boost.org/libs/smart_ptr/shared_ptr.htm states that "T may be void, but in that case, either an explicit delete function must be passed in, or the pointed-to object must have a trivial destructor." I notice that the implementation available at boost.org does not allow the single-argument ctor to be called on an incomplete type, e.g.: class simple; simple * createSimple(); shared_ptr<simple> simpleFactory() { return shared_ptr<simple>(createSimple()); } The documentation on the single-argument ctor, though, does not state that T must be a complete type. Is the implementation stricter than the documentation, or is the documentation incomplete? I'm writing an article on the smart pointers for the CUJ, and I'd like to know if I can correctly state "The default behavior for shared_ptr is to require complete types. You can, however, manage an incomplete type if you provide a function or function object, which will be called when the owned object is destroyed." -- Jim

3 2

Graph Library - AllExamples.dsw, anyone got it?
by loopylozzysdad 30 Apr '02

30 Apr '02

Hi All, Just read the excellent Boost Graph Library book. The AllExamples.dsw file is not on the accompanying CD. In the Errata web page (http://siek.info/bgl.html) it says... "On the accompanying CD, the file \BGL\VC++ Projects\AllExamples.dsw is missing. You can download the missing file from here BGLVCprojects.tgz." The file there is a .dsw file but it is NOT the missing one. Has anyone got the real thing? All the best and thanks - Richard Howells

1 0

Re: Boost.Thread (VC specific)
by Holger Thiele 30 Apr '02

30 Apr '02

>-----Ursprungliche Nachricht----- >Von: bill_kempf [mailto:williamkempf@hotmail.com] >Gesendet: Dienstag, 30. April 2002 17:54 >An: Boost-Users(a)yahoogroups.com >Betreff: [Boost-Users] Re: Boost.Thread (VC specific) > > >I don't agree. If it's a good idea, then I'd expect MS to do this by >default for IDE generated builds. Such as default warning level 3? >There's some overhead involved in >generating this, there's compile time overhead (which is important to >some) Do you have figures on that? In my experience, this overhead seems to be a small price to pay for the ability to track bugs (inside your debugger!) on released code. >and there's the fact that many users will be confused by the >presence of debug information and why "stepping" through the code >behaves so strangely and unpredictably. As always, if someone doesn't know what he's doing, there's little help besides getting educated. But, seriously, I think that most users that even get into debugging release builds would surely appreciate library code that supports this. Just my 2 cents. Cheers, and thanks for one of my favorite libraries Holger Thiele D.A.V.I.D. GmbH www.david-gmbh.de

1 0

RE: [Boost-Users] operator == in shared_ptr
by bjorn.karlsson＠readsoft.com 30 Apr '02

30 Apr '02

> From: sashan [mailto:sashang@ihug.co.nz] [snip] > Is there a better way that doesn't involve 1) having to write > a wrapper class around a basic type (or any type) and 2) > doesn't involve changing the shared_ptr::operator==. > As others have pointed out, the solution is to use a function object and std::find_if. In this case, the comparison doesn't even need a separate predicate - the (exceptionally cool) Boost.Bind library can be used instead: vector<shared_ptr<int> >::iterator it=std::find_if(vec.begin(),vec.end(),bind(std::equal_to<int>(),bind(&shared _ptr<int>::operator*, _1),42)); Bjorn Karlsson [Non-text portions of this message have been removed]

1 0

operator == in shared_ptr
by sashan 30 Apr '02

30 Apr '02

Hi Because the operator== function compares pointers and not what they're pointing to this is what I've had to do to get it to find an integer. Basically I had to wrap the basic int type within another class called Int, as show below. class Int { private: shared_ptr<int> p; public: Int(int i) {p.reset(new int); *p = i;} bool operator==(const Int& r) {return *p.get() == *r.p.get();} ~Int() {}; }; void main() { vector < Int > vec; vec.push_back(Int(1)); vec.push_back(Int(2)); vec.push_back(Int(3)); Int p(4); if (find(vec.begin(), vec.end(), p) == vec.end()) { cout << "Couldn't find it"; } } Is there a better way that doesn't involve 1) having to write a wrapper class around a basic type (or any type) and 2) doesn't involve changing the shared_ptr::operator==. [Non-text portions of this message have been removed]

3 2

boost::function::set()
by Douglas Gregor 29 Apr '02

29 Apr '02

Does anyone use the boost::function::set() methods? I'd like to remove them for Boost.Function v2 to cut down on the size of the interface. If you are using set() and would like to keep using it, please tell me. Doug

1 0

RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 29 Apr '02

29 Apr '02

Toon Knapen wrote: > On Friday 26 April 2002 13:37, Aleksey Gurtovoy wrote: > > Toon Knapen wrote: > > > I have a list of heterogeneous objects, e.g. > [snip sample code] > > > > And now I want to have a function that can accumulate the > > > value sof all the objects in the tuple, e.g. (pseudocode since > > > my problem is exacly that I can't figure out how to code this) > > > > > > template < typename TypleType > > > > int accumulate_values(const TupleType& t) > > > { > > > int acc = 0; > > > for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( > t )).value(); > > > } > > > > > > Can I do this using mpl (mpl looks great but I can't figure > > > out how to do this). > > > > It's not exactly a part of MPL (the library doesn't target > "run-time" stuff > > to that extent yet; I hope it will some day), but "tuple extension" > > components I wrote some time ago > > > (http://groups.yahoo.com/group/boost/files/tuple_ext/tuple_ext-08-nov-01.zip ) > allow one to do exactly these kinds of things: > [snip aleksey's solution] > > Thanks, I like tuple_ext a _lot_ ! I am glad you found it useful. > It would be great to have complete STL-like functionality like this. Yep. The only problem with this is that we are going to end up with 3 STL-like libraries within the same language :) (the original one ("run-time"), the MPL one (pure compile time), and something in between, - HSTL (Heterogeneous Sequences Template Library :)). All three with the same algorithms, just written in different notation :). Emily's heterogeneous lists (www.oonumerics.org/tmpw01/winch.pdf, http://groups.yahoo.com/group/boost/files/alist-feb14-02.zip) 'tuple_ext' components, and MPL's v.2 half-run-time 'for_each' are obviously hanging around that "in between" thing. > Plans on adding this tuple_ext to the CVS ? Some; I think it should be a full-fledged submission that would take the prior art and build a simple framework on it. It's not a large undertaking, though - most of the concepts and some code are already here :). Aleksey

1 0

BGL: "Supergraphs?"
by David A. Greene 29 Apr '02

29 Apr '02

Hi, I've been learning the BGL and porting some existing code over to it. First off, Kudos to Jeremy, Lie-Quan and all the BGL developers. This library is great! I find the filtered_graph potentially very useful for my application except for one case. In some (not rare) instances I need to be able to create a filtered_graph that spans two graphs. In other words, I have two separate graphs. Most of the time the information I need is entirely contained in one graph so a filtered_graph works perfectly. However, sometimes I need to create a filtered_graph from several separate graphs and link them together in a well-defined manner (i.e. I easily know where the edges should go). I need a "supergraph" that is the combination of the two filtered graphs. Right now the application handles this problem by creating a new graph from the existing graphs. But this takes time and memory. I'd like to get rid of this overhead if possible, especially since these are often short-lived graphs. The filtered_graph objects would not be induced subgraphs so a subgraph object wouldn't work (subgraph also doesn't support something that spans multiple graphs anyway). What I need is the opposite of subgraph -- a unified interface to multiple filtered_graphs. This seems very hard to do because each filtered_graph will have its own vertex and edge index mappings. An extra level of indirection would solve the problem but I'm not sure the overhead would be less than simply creating a new graph. Thoughts? Opinions? Thanks again for a great library! -Dave -- "Some little people have music in them, but Fats, he was all music, and you know how big he was." -- James P. Johnson

3 6

Newbie: problems installing under RedHat 7.2
by Benjamin Han 28 Apr '02

28 Apr '02

I'm just trying to install Boost library under RedHat 7.2. I was following the build instructions found on the Boost website, but it seemed to fail for several targets. I'm wondering if it's because RH7.2 uses its version of gcc 2.96. Since my project work needs gcc 3.0+, my question is, what do I need to do in order to use gcc3/g++3 instead of gcc/g++? The build system seems exotic and I just want to get over with the installation asap and start to use the library. (does changing /usr/bin/gcc and /usr/bin/g++ links work?) Here is the build command I tried: jam -sBOOST_ROOT=. -sTOOLS="gcc" Errors (selected): ... libs/thread/build/../src/once.cpp: In function `void boost::call_once (void (*) (), once_flag &)': boost/thread/once.hpp:38: previous declaration of `void boost::call_once (void (*) (), once_flag &)' with C++ linkage libs/thread/build/../src/once.cpp:77: conflicts with new declaration ... MkDir1 libs/python/build/bin/libboost_python_static/gcc/debug/runtime-link-dynam ic/shared-linkable-true gcc-C++-action libs/python/build/bin/libboost_python_static/gcc/debug/runtime-li nk-dynamic/shared-linkable-true/types.o In file included from boost/python/errors.hpp:13, from boost/python/detail/call_object.hpp:8, from libs/python/build/../src/types.cpp:11: boost/python/detail/wrap_python.hpp:24:24: patchlevel.h: No such file or directo ry boost/python/detail/wrap_python.hpp:100:20: Python.h: No such file or directory ... (lots of Python-related errors) ... gcc-C++-action status/bin/is_function_test/gcc/debug/runtime-link-dynamic/is_fun ction_test.o boost/type_traits/function_traits.hpp: In instantiation of `boost::is_function<i nt[]>': status/../libs/type_traits/tests/is_function_test.cpp:68: instantiated from he re boost/type_traits/function_traits.hpp:148: Internal error: Segmentation fault. Please submit a full bug report. See <URL:http://bugzilla.redhat.com/bugzilla/> for instructions. ... &boost::noncopyable::operator= (const boost::noncopyable &)' is private status/../libs/utility/noncopyable_test.cpp:35: within this context ...failed updating 43 targets... ...skipped 24 targets... ...updated 629 targets... The folllowing RPMs are installed on the machine: 1. gcc-2.96-110 2. gcc3-3.1-0.23.1 3. python-1.5.2-38 4. python2-2.2-16 5. glibc-2.2.5-32 6. boost-build-1.0-1 7. boost-jam-3.0-1 Other info: kernel 2.4.18 (manually built) Any comment would be greatly appreciated, Ben

3 3

RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 28 Apr '02

28 Apr '02

Toon Knapen wrote: > I have a list of heterogeneous objects, e.g. > > struct Foo { > Foo(int v) : value_( v ) {} > int value() const { return value_ ; } > int value_; > }; > > struct Bar { > Bar(int v) : value_( v ) {} > int value() const { return value_ ; } > int value_; > }; > > int main() > { > Foo foo(3); > Bar bar(7); > typedef boost::tuple< Foo, Bar > MyTuple ; > MyTuple my_tuple( foo, bar ); > return 0; > } > > And now I want to have a function that can accumulate the > value sof all the objects in the tuple, e.g. (pseudocode since > my problem is exacly that I can't figure out how to code this) > > template < typename TypleType > > int accumulate_values(const TupleType& t) > { > int acc = 0; > for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( t )).value(); > } > > Can I do this using mpl (mpl looks great but I can't figure > out how to do this). It's not exactly a part of MPL (the library doesn't target "run-time" stuff to that extent yet; I hope it will some day), but "tuple extension" components I wrote some time ago (http://groups.yahoo.com/group/boost/files/tuple_ext/tuple_ext-08-nov-01.zip ) allow one to do exactly these kinds of things: // untested! :) template< typename Seq, typename T, typename BinaryOp > T accumulate(Seq const& s, T const& Init, BinaryOp op) { T result = Init; for_each( begin(s) , end(s) , boost::bind<T>(op, boost::ref(result), _1) ); return result; } With the above, you can do something like this: struct get_value { template< typename T > int operator()(T const& x) const { return x.value(); } }; int sum = accumulate( tuple , 0 , boost::bind(std::plus<int>() , _1 , boost::bind<int>(get_value(),_2) ) ); Hope it's not too complicated :). LL might allow to do better on this one. Aleksey

2 2

iterating over a tuple
by Toon Knapen 26 Apr '02

26 Apr '02

I have a list of heterogeneous objects, e.g. struct Foo { Foo(int v) : value_( v ) {} int value() const { return value_ ; } int value_; }; struct Bar { Bar(int v) : value_( v ) {} int value() const { return value_ ; } int value_; }; int main() { Foo foo(3); Bar bar(7); typedef boost::tuple< Foo, Bar > MyTuple ; MyTuple my_tuple( foo, bar ); return 0; } And now I want to have a function that can accumulate the value sof all the objects in the tuple, e.g. (pseudocode since my problem is exacly that I can't figure out how to code this) template < typename TypleType > int accumulate_values(const TupleType& t) { int acc = 0; for(int i = 0 ; i < t.size() ; ++i ) acc += (get< i >( t )).value(); } Can I do this using mpl (mpl looks great but I can't figure out how to do this). thanks, toon

1 0

RE: [Boost-Users] iterating over a tuple
by Aleksey Gurtovoy 26 Apr '02

26 Apr '02

Toon Knapen wrote: > > Hope it's not too complicated :). LL might allow to do > > better on this one. > > Thanks, I'll try it out. Coudl you enlighten me on how to > solve it with the lambda library. I don't see how to iterate over > the different indexes in combination with LL ? Oh, sorry, my last sentence was probably misleading. What I meant is that LL can do a better job on construction of the function object that is passed to tuple's 'accumulate': struct get_value { template< typename T > int operator()(T const& x) const { return x.value(); } }; int sum = accumulate(tuple, 0, _1 + ll::bind(get_value(),_2)); I was also hoping that it could help us to get rid of the ad hoc 'get_value' class, but, thinking about it more, I don't see how :(. HTH, Aleksey

1 0