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

Possible boost addition: sub string and const string.
by alexei_novakov 19 Nov '02

19 Nov '02

Hello everyone. I have two classes which I found pretty handy: sub_string (behaves as a mirror of the portion of master basic_string) and const_string (C- string wrapper). Nice thing about these two is they implemented as template specialization of basic_string which has advantages: a) familiar interface; b) possibility to reuse the code written for basic_string (like string streams, lexical casts, etc). Any interest? Regards. Alexei Novakov

1 0

Forte 7 Compiler
by ewanbrock 18 Nov '02

18 Nov '02

Hi, I'm trying to compile Boost using the Solaris Forte 7 Compiler. Initial attempts are leading to all sorts of assertion errors. Has anyone had success using boost with this compiler? Does anyone know what the Config options should be ? Many thanks, Ewan

1 0

[BGL] vc6&7 doesn't support partial specialization,can I still use BGL in vc?
by Jun Zhang 18 Nov '02

18 Nov '02

I can't believe it is vc7!! still missing support for partial specialization. Do you know other method to let vc compile BGL codes used partial specialization? Need your help. Jun Zhang

1 0

adjacency_list going out of memory range?
by Ramón Casero Cañas 18 Nov '02

18 Nov '02

Hi, I'm working with GNU/Linux, Debian Sarge, libboost-graph1.28.0, gcc version 2.95.4 20011002 (Debian prerelease). I'm quite new to this, so I don't know if I'll be able to explain my problem correctly. It seems to me as if when I declare a graph, it writes on memory already used by another data structure. The parts of the code that I consider relevant are (.hpp and .cpp merged) ------------------- | | \|/ ------------------- #include <utility> // for std::pair #include <boost/graph/adjacency_list.hpp>/* for namespace boost * vertex_index_t * edge_weight_t * listS * undirectedS */ using namespace boost; namespace boost { enum vertex_to_be_spanned_t { // used to mark vertices of W vertex_to_be_spanned }; BOOST_INSTALL_PROPERTY(vertex, to_be_spanned); } namespace steiner { typedef std::pair<int,int> Edge; // type of edges /* Steiner Problem Graph: * - multigraph * - add_edge(), ... stability and speed, bad space overhead * - vertex indices, edge weights */ typedef property <vertex_index_t, int, property <vertex_to_be_spanned_t, bool> > VertexProperty; typedef property <edge_weight_t, int> EdgeProperty; typedef adjacency_list <listS, listS, undirectedS, VertexProperty, EdgeProperty > SteinerGraph; } namespace steiner { #define EX_FORMAT "not a valid steiner problem file"; } #include <iostream> // for std::cout #include <fstream> // for std::ifstream using namespace steiner; namespace steiner { int readsteinerORfile(steiner::SteinerGraph& g, char *s); } namespace steiner { inline void skipspaces(std::ifstream& fp, char& c); } namespace steiner { inline int readchar2int(std::ifstream& fp, char& c); } /* int main(int argc, char *argv[]) * -------------------------------- * *argv[] (IN): file names array * -------------------------------- * return n: n files were succesfully read, n > 0 * return 0: no files could be read * return -1: unexpected error * -------------------------------- * read steiner problem from files */ int main(int argc, char *argv[]) { ... SteinerGraph g; nf = steiner::readsteinerORfile(g, argv[i]); ... } /* int readsteinerORfile(VertexListGraph& g, char *s) * -------------------------------- * g (OUT): graph read from file * *s (IN): file name * -------------------------------- * return 1: file successfully read * return 0: file could not be read * return -1: unexpected error * -------------------------------- * read steiner problem from one file */ namespace steiner { int readsteinerORfile(steiner::SteinerGraph& g, char *s) { ... int num_edg=0, num_ver=0, // number of edges, vertices num_verw=0; // number of non-steiner vertices char c; // file reader int i; // counter int x; // temp value int *weight_array=NULL; // edge weights read from file Edge *edge_array=NULL; // array of edges read from file int *w_array=NULL; // vertices of W ... weight_array = new int[num_edg]; if (weight_array == NULL) throw (char *)EX_MEM; edge_array = new Edge[num_edg]; if (edge_array == NULL) throw (char *)EX_MEM; w_array = new int[num_verw]; if (w_array == NULL) throw (char *)EX_MEM; ... *************** HERE ******************* /* creation of graph object */ g.clear(); g = SteinerGraph(num_ver); *************** HERE ******************* ... } } ------------------- | | \|/ ------------------- And what happens? If I print the contents of w_array[] at the first "HERE", I get Puf(W(0)=0 )! Puf(W(1)=1 )! Puf(W(2)=2 )! Puf(W(3)=3 )! but if I print them again at the second "HERE", I get Puf(W(0)=8 )! Puf(W(1)=1 )! Puf(W(2)=2 )! Puf(W(3)=-15 )! Does anybody knows what could be happening? Thank you. Regards, Ramón Casero.

2 2

RE: [Boost-Users] Getting a matrix to the power of n
by Scott Sinclair 17 Nov '02

17 Nov '02

Hi Unless I've missed something, I don't think uBlas provides a way to do this (other than the _very_ inefficient prod(A, A) in a loop). If you need to do this frequently with large matrices and/or large powers (n) then you'll need to look at diagonalizing your matrix using eigenvalue/vector decomposition. This reduces your task to raising the values on the diagonal of a diagonal matrix to the power of n and doing two matrix multiplies and an inverse. Finding the eigenvalues and corresponding eigenvectors of your matrix is a non-trivial task which imposes some restrictions on your matrix. Refer to "Numerical recipes in C" by Press et al. for some guidance as well as any good textbook on linear algebra. Hope this helps, Scott > -----Original Message----- > From: agiatojon [mailto:JonAgiato@nyc.rr.com] > Sent: 14/11/2002 14:17 > To: Boost-Users(a)yahoogroups.com > Subject: [Boost-Users] Getting a matrix to the power of n > > > Hello all, > I am working with a formula which requires me to get the result of a > matrix to the power of n (i.e. pow(matrix, n)) but as expected, the > <cmath> function pow() is unable to convert from type double to > matrix. Does the matrix library have this sort of functionality > built in, or maybe some other part of boost? Thanks! > > Jon Agiato > JonAgiato(a)nyc.rr.com The contents of this email may be confidential. Unauthorised use is prohibited. Umgeni Water does not accept liability for any statements and opinions which are the sender's own view and not expressly made on its behalf.

3 2

Using multi_array/matrix to wrap a SAFEARRAY
by Nick Toze 17 Nov '02

17 Nov '02

Hello, I haven't really used C++ much (more Java and Eiffel), but now I am helping develop a C++ dll that will use matrices alot and will probably need to use SAFEARRAY to interface with Visual Basic (either directly or via COM). Also the group I'm in need to standardize on a matrix representation and it needs to be compatible with NAG. I've been trying to wrap a SAFEARRAY using a multi_array and I've got something that seems to work (see attached), but :-) I'm not sure how to go about passing these (i.e. multi_array, multi_array_ref, const_multi_array_ref) around as function arguments since they don't have any inheritance relationship. Do you have any suggestions on that? Maybe template functions could be used, but I'd like to keep my code fairly simple since I'm no expert. As an alternative the uBLAS container classes look very appropriate since I'll only be passing numbers and some of the algorithms could be useful (although I'll mostly be using NAG), but I couldn't quite see whether it is possible to use a uBLAS matrix as a view onto the data in a SAFEARRAY. Is it possible to attach a pointer to an array to a uBLAS matrix? This is the code I've got as an example for wrapping a SAFEARRAY: typedef boost::multi_array_ref<double, 2> dbl_matrix_ref; typedef boost::multi_array<double, 2> dbl_matrix; __declspec(dllexport) HRESULT __stdcall mmultiply(SAFEARRAY** sa1, SAFEARRAY** sa2, SAFEARRAY** result) { HRESULT hr; if ( result == NULL ) return E_INVALIDARG; if ( (*sa1)->cDims != 2 ) return E_INVALIDARG; if ( (*sa1)->cbElements != 8 ) return E_INVALIDARG; if ( (*sa2)->cDims != 2 ) return E_INVALIDARG; if ( (*sa2)->cbElements != 8 ) return E_INVALIDARG; long m1_dim0_sz, m1_dim1_sz, m2_dim0_sz, m2_dim1_sz; m1_dim0_sz = (*sa1)->rgsabound[0].cElements; m1_dim1_sz = (*sa1)->rgsabound[1].cElements; m2_dim0_sz = (*sa2)->rgsabound[0].cElements; m2_dim1_sz = (*sa2)->rgsabound[1].cElements; hr = SafeArrayLock( *sa1 ); if ( FAILED(hr) ) return hr; hr = SafeArrayLock( *sa2 ); if ( FAILED(hr) ) return hr; dbl_matrix_ref matrix1( (double*)(*sa1)->pvData, boost::extents[m1_dim1_sz][m1_dim0_sz], boost::fortran_storage_order() ); dbl_matrix_ref matrix2( (double*)(*sa2)->pvData, boost::extents[m2_dim1_sz][m2_dim0_sz], boost::fortran_storage_order() ); dbl_matrix matrix_result( boost::extents[matrix1.shape()[0]][matrix2.shape()[1]], boost::fortran_storage_order() ); for (dbl_matrix_ref::index i = 0; i != matrix1.shape()[0]; ++i) { for (dbl_matrix_ref::index j = 0; j != matrix2.shape()[1]; ++j) { double s = 0; for (dbl_matrix_ref::index k = 0; k != matrix1.shape()[1]; ++k) { s = s + matrix1[i][k] * matrix2[k][j]; } matrix_result[i][j] = s; } } SAFEARRAYBOUND rgsabound[2]; rgsabound[0].lLbound = 0; rgsabound[0].cElements = matrix_result.shape()[0]; rgsabound[1].lLbound = 0; rgsabound[1].cElements = matrix_result.shape()[1]; SAFEARRAY* lresult = SafeArrayCreate(VT_R8, 2, rgsabound); lresult->pvData = matrix_result.data(); hr = SafeArrayCopy( lresult, result ); if ( FAILED(hr) ) return hr; hr = SafeArrayDestroy( lresult ); if ( FAILED(hr) ) return hr; hr = SafeArrayUnlock( *sa1 ); if ( FAILED(hr) ) return hr; hr = SafeArrayUnlock( *sa2 ); if ( FAILED(hr) ) return hr; return S_OK; } Then I declare this in VBA with: Declare Function mmultiply Lib _ "D:\multiarray_test\Debug\multiarray_test" _ (a() As Double, b() As Double, c() As Double) As Long

2 1

using 'this' with shared_ptrs
by Stephen Crowley 17 Nov '02

17 Nov '02

How is someone supposed to use 'this' when setting a member of another class to point back to it? Here is an example.. when you run it, this will happen. constructor called 0x804af10 constructor called 0x804af48 destructor called 0x804af48 destructor called 0x804af10 destructor called 0x804af10 The last destructor is called twice! The only way I can think to get around this add a member to the class called "shared_ptr<MyClass> thisptr" which is initialized to "this" in the constructor and over-ride the assignment operator or something.. will that work? ------------------------ #include <boost/shared_ptr.hpp> #include <boost/weak_ptr.hpp> #include <iostream> using namespace std; using namespace boost; class MyClass; typedef shared_ptr<MyClass> MyClassPtr; class MyClass { public: MyClass(); ~MyClass(); MyClassPtr makeCopy(); MyClassPtr original; }; MyClass::MyClass() { cout << "constructor called " << this << endl; } MyClass::~MyClass() { cout << "destructor called " << this << endl; } MyClassPtr MyClass::makeCopy() { MyClassPtr mc(new MyClass); mc->original = MyClassPtr(this); return mc; } main() { MyClassPtr oc(new MyClass); MyClassPtr cc = oc->makeCopy(); // the problem lies here // when cc's reference count is 0 it will be deleted, which will // in turn decrease its 'original' reference count which will be 0, thus // causing it to be deleted as well even though it is still being used by oc! cc.reset(); } ----------------------------------- -- Stephen

2 2

Date_time library question...
by shaneforbes 16 Nov '02

16 Nov '02

With the following line in my Microsoft Vc7 program: std::cout << to_simple_string(d) << std::endl; I get the following linker errors: error LNK2005: "public: __thiscall std::locale::id::id(unsigned int)" (??0id@locale@std@@QAE@I@Z) already defined in stdafx.obj error LNK2005: "private: __thiscall type_info::type_info(class type_info const &)" (??0type_info@@AAE@ABV0@@Z) already defined in LIBCD.lib(typinfo.obj) error LNK2005: "private: class type_info & __thiscall type_info::operator=(class type_info const &)" (?? 4type_info@@AAEAAV0@ABV0@@Z) already defined in LIBCD.lib(typinfo.obj) Clearly I am missing something important! I did put #define DATE_TIME_INLINE in my stdafx.h file and that allowed me to create dates (date d(...)) but clearly something else is needed (for IO related stuff?)... Do I have to for instance recreate the libboost_date_time.lib file with different settings? I just used 'bjam "-sTOOLS=vc7" "- sBUILD=debug release"'. Any help appreciated. Thanks to Jeff Garland and the rest of the Boost group for creating this library - I would really like to use it in my programs from now on but why won't the silly linker oblige!

2 8

Codewarrior 8 and Include Paths
by Roland Weiss 15 Nov '02

15 Nov '02

Hello, I'm trying to compile some simple test programs that use Boost Header libraries (no building required), like any, shared_ptr etc. Using CW8, I have a strange problem. When I add the Boost root to the access path, the compiler finds the according boost headers, but inside the config header the Boost lib looks up some headers using this syntax: #include <user.hpp> and so on. CW8 then fails to find these headers. If I change <user.hpp> to "user.hpp" all works fine (but it fails on the next header in angle brackets). Any help appreciated. Roland

2 2

uBlass outer_product
by Olaf Petzold 15 Nov '02

15 Nov '02

Hi, I can't get the following snipped from the doc examples to work: #include <iostream> #include <boost/numeric/ublas/vector.hpp> #include <boost/numeric/ublas/io.hpp> int main () { using namespace boost::numeric::ublas; vector<double> v1 (3), v2 (3); for (int i = 0; i < std::min (v1.size (), v2.size ()); ++ i) v1 (i) = v2 (i) = i; std::cout << outer_prod (v1, v2) << std::endl; } ublas_cross.cc: In function `int main()': ublas_cross.cc:17: `outer_prod' undeclared (first use this function) ublas_cross.cc:17: (Each undeclared identifier is reported only once for each function it appears in.) What's wrong here? Thanks Olaf

2 1

RE: [Boost-Users] using 'this' with shared_ptrs
by Per Kristensen 15 Nov '02

15 Nov '02

You initialises two shared_ptr with the same raw pointer. As a consequent the destructor is called twice, as you will have two different shared_count object which will calls delete as the count become zero. Try to use weak_ptr as a member: ----------------------------------- typedef shared_ptr<MyClass> MyClassPtr; class MyClass { public: MyClass(); ~MyClass(); void setOriginal(MyClassPtr); MyClassPtr makeCopy(); weak_ptr<MyClass> original; }; MyClass::MyClass() { cout << "constructor called " << this << endl; } MyClass::~MyClass() { cout << "destructor called " << this << endl; } void MyClass::setOriginal(MyClassPtr p) { original = p; } MyClassPtr MyClass::makeCopy() { return MyClassPtr(original); } main() { MyClassPtr oc(new MyClass); oc->setOriginal(oc); MyClassPtr cc = oc->makeCopy(); } --------------------------------- Per -----Original Message----- From: Stephen Crowley [mailto:stephenc@digitalpassage.com] Sent: 15. november 2002 05:37 To: Boost-Users(a)yahoogroups.com Subject: [Boost-Users] using 'this' with shared_ptrs How is someone supposed to use 'this' when setting a member of another class to point back to it? Here is an example.. when you run it, this will happen. constructor called 0x804af10 constructor called 0x804af48 destructor called 0x804af48 destructor called 0x804af10 destructor called 0x804af10 The last destructor is called twice! The only way I can think to get around this add a member to the class called "shared_ptr<MyClass> thisptr" which is initialized to "this" in the constructor and over-ride the assignment operator or something.. will that work? ------------------------ #include <boost/shared_ptr.hpp> #include <boost/weak_ptr.hpp> #include <iostream> using namespace std; using namespace boost; class MyClass; typedef shared_ptr<MyClass> MyClassPtr; class MyClass { public: MyClass(); ~MyClass(); MyClassPtr makeCopy(); MyClassPtr original; }; MyClass::MyClass() { cout << "constructor called " << this << endl; } MyClass::~MyClass() { cout << "destructor called " << this << endl; } MyClassPtr MyClass::makeCopy() { MyClassPtr mc(new MyClass); mc->original = MyClassPtr(this); return mc; } main() { MyClassPtr oc(new MyClass); MyClassPtr cc = oc->makeCopy(); // the problem lies here // when cc's reference count is 0 it will be deleted, which will // in turn decrease its 'original' reference count which will be 0, thus // causing it to be deleted as well even though it is still being used by oc! cc.reset(); } ----------------------------------- -- Stephen Info: < http://www.boost.org> Wiki: < http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> . [Non-text portions of this message have been removed]

1 0

graph question : cycle detection - undirected graph
by Matthew Galati 15 Nov '02

15 Nov '02

Can DFS be used to detect cycles in an undirected graph? Using the code in the example file_dependencies.cpp on an undirected graph - it detects cycles even though there is none. Do we have to do more than simply look for back edges for an undirected graph? or should I convert it to directed then use this function? Thanks, Matt -- Matthew Galati ISE Lehigh University IBM Service Parts Solutions 610.758.4042 (Office) 610.882.0779 (Home) magh(a)lehigh.edu, magal11(a)us.ibm.com http://sagan.ie.lehigh.edu/mgalati/

2 1

Getting a matrix to the -1 power
by agiatojon 14 Nov '02

14 Nov '02

Hello all, I am trying to evaluate a matrix to the -1 power but have not been able to find a quick and dirty solution. Any suggestions? Thanks! Jon Agiato JonAgiato(a)nyc.rr.com

1 0

Preprocessor lib problems on Solaris (Forte compiler)
by Robert A. Reece 14 Nov '02

14 Nov '02

I'm using Forte 6 update 2 to compile my code. The preprocessor headers seem to have problems with all the various macros that get defined. These are the errors I'm seeing from compiling libs/preprocessor/test/list.cpp (using command CC -I../../.. list.cpp): /hades03/pegstage/boost/boost_1_29_0/libs/preprocessor/test> /../.. list.cpp < "list.cpp", line 24: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 24: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 24: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 24: Error: BOOST_PP_NIL is not defined. "list.cpp", line 24: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 24: Error: Badly formed expression. "list.cpp", line 25: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 25: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 25: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 25: Error: BOOST_PP_NIL is not defined. "list.cpp", line 25: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 25: Error: Badly formed expression. "list.cpp", line 26: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 26: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 26: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 26: Error: BOOST_PP_NIL is not defined. "list.cpp", line 26: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 26: Error: Badly formed expression. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 28: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 28: Error: BOOST_PP_NIL is not defined. "list.cpp", line 28: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 28: Error: Badly formed expression. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 30: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 30: Error: BOOST_PP_NIL is not defined. "list.cpp", line 30: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 30: Error: Badly formed expression. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 31: Error: BOOST_PP_LIST_FOLD_LEFT_129 is not defined. "list.cpp", line 31: Error: BOOST_PP_NIL is not defined. "list.cpp", line 31: Error: BOOST_PP_TUPLE_EAT_3 is not defined. "list.cpp", line 31: Error: Badly formed expression. "list.cpp", line 33: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 33: Warning: Too few arguments in macro BOOST_PP_CHECK_2. "list.cpp", line 33: Error: BOOST_PP_LIST_FIRST_I is not defined. Compilation aborted, too many Error messages. Any thoughts would be great. -Rob

4 6

RE: [Boost-Users] A strange question-)
by Aleksey Gurtovoy 14 Nov '02

14 Nov '02

Sam Gentile wrote: > I'm sorry, no I still don't understand. Could you please say more? Well, it would help me if you've said what exact points in my answer you are having troubles with :). Aleksey > > -----Original Message----- > From: Aleksey Gurtovoy [mailto:alexy@meta-comm.com] > Sent: Wednesday, November 13, 2002 3:19 AM > To: 'Boost-Users(a)yahoogroups.com' > Subject: RE: [Boost-Users] A strange question-) > > > > Sam Gentile wrote: > > I went there and indeed it can't get any simpler - at least > > in theory-) > > Read the document > > C:\Boost\boost_1_29_0\libs\type_traits\c++_type_traits.htm > > and its quite > > simple: > > > > template <typename T> > > struct is_void > > { static const bool value = false; }; > > > > template <> > > struct is_void<void> > > { static const bool value = true; }; > > > > That's exactly what I want to show. So I go to the header files and > > instead: > > > > //* is a type T void - is_void<T> > > > > BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_void,T,false) > > > > BOOST_TT_AUX_BOOL_TRAIT_SPEC1(is_void,void,true) > > > > > > > > Huh? So I look in bool_trait_def.hpp: > > > > #define BOOST_TT_AUX_BOOL_TRAIT_DEF1(trait,T,C) \ > > > > template< typename T > struct trait \ > > > > : mpl::bool_c< C > \ > > > > { \ > > > > BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(C) \ > > > > BOOST_MPL_AUX_LAMBDA_SUPPORT(1,trait,(T)) \ > > > > }; \ > > > Well, the original code doesn't have all these excessive newlines ;), > but > yes, basically that's how it's implemented. > > > Argh! Why is it done like this? This makes it much more > > complicated and unreadable than it has to be. Why are macros > > being used everywhere? > > Practical engineering matters. If you consider that the fact > that there > are > ~60 trait templates in the library and every time when a new > version of > a > compiler comes out, or when somebody starts porting the > library to a new > platform, there is a chance that you need to change half of those > definitions, from, for instance, > > template <typename T> > struct is_void > : mpl::bool_c<false> > { > }; > > to > > template <typename T> > struct is_void > { > BOOST_STATIC_CONSTANT(bool, value = false); > typedef mpl::bool_c<value> type; > }; > > it might all make sense, after all :). Something along the > lines of both > of > the above scenarios has actually happened, a couple of times. It's not > the > whole picture yet, but IMO it's enough of the motivation already, so I > won't > go too deep into details :). > > Hope this answers your question, > Aleksey > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to the Yahoo! > <http://docs.yahoo.com/info/terms/> Terms of Service. > > > > [Non-text portions of this message have been removed] > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > 4 DVDs Free +s&p Join Now > http://us.click.yahoo.com/pt6YBB/NXiEAA/ASSHAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

4 4

RE: [Boost-Users] A strange question-)
by Jim.Hyslop 14 Nov '02

14 Nov '02

Sam Gentile [mailto:ManagedCode@attbi.com] wrote: > Well at least you gave somewhat of an answer. I still want to > understand > how those particular macros give that portability. I haven't looked at the macros in question, but one approach to portability is to separate the macro definitions into platform-specific files. Exactly which file gets included depends on the compiler settings. For example: // file: compilerX/defines.h [omitting include guards for brevity #define DO_SOMETHING(x) CallCompilerXFn( x ) // end file // file: compilerY/defines.h #define DO_SOMETHING(x) compiler_y_function( x ) // end file // file: some Boost header #include "defines.h" class someClass { void f(T a) { DO_SOMETHING( a ); } }; Exactly _which_ "defines.h" gets included is controlled by the build settings, which are determined by the platform. The alternative is a really ugly set of #ifdefs: // file: some Boost header class someClass { void f(T a) { #ifdef COMPILER_X CallCompilerXFn( a ); #elif defined(COMPILER_Y) compiler_y_function( a ); [... etc. for each platform supported #endif } }; As I said, that's _one_ approach - Boost uses something slightly different. Have a look at config.hpp to see its approach. -- Jim

1 0

RE: [Boost-Users] A strange question-)
by Tom Matelich 14 Nov '02

14 Nov '02

Can't say for sure if it'll be helpful, but you might trace the file's evolution using the web interface to cvs on sourceforge. > -----Original Message----- > From: Sam Gentile [mailto:ManagedCode@attbi.com] > Sent: Thursday, November 14, 2002 10:28 AM > To: Boost-Users(a)yahoogroups.com > Subject: RE: [Boost-Users] A strange question-) > > > You're right of course. I do realize that everyone works on this in > their "free time," and what has been accomplished has been > astounding to > say the least. I'm sorry for my rant and I'll re-look at his reply and > try to figure it out. Once again, I apologize. > > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

1 0

RE: [Boost-Users] A strange question-)
by Garriss, Michael 14 Nov '02

14 Nov '02

No problem. We all know how frustrating C++ can be sometimes :) . You're right, what they have done is astounding! -Mike -----Original Message----- From: Sam Gentile [mailto:ManagedCode@attbi.com] Sent: Thursday, November 14, 2002 11:28 AM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] A strange question-) You're right of course. I do realize that everyone works on this in their "free time," and what has been accomplished has been astounding to say the least. I'm sorry for my rant and I'll re-look at his reply and try to figure it out. Once again, I apologize. Sam Gentile .NET Consultant ManagedCode(a)nospam.attbi.com http://www.samgentile.com http://radio.weblogs.com/0105852/ -----Original Message----- From: Garriss, Michael [mailto:michael.garriss@abacus-direct.com] Sent: Thursday, November 14, 2002 12:57 PM To: 'Boost-Users(a)yahoogroups.com' Subject: RE: [Boost-Users] A strange question-) Keep in mind that Aleksey doesn't get paid for this and he answered your mail on his "free" time. Cut him some slack! I thought his answers for well written. -Mike Garriss -----Original Message----- From: Sam Gentile [mailto:ManagedCode@attbi.com] Sent: Thursday, November 14, 2002 9:29 AM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] A strange question-) Well at least you gave somewhat of an answer. I still want to understand how those particular macros give that portability. Sam Gentile .NET Consultant ManagedCode(a)nospam.attbi.com http://www.samgentile.com http://radio.weblogs.com/0105852/ -----Original Message----- From: Jeff Garland [mailto:jeff@crystalclearsoftware.com] Sent: Thursday, November 14, 2002 11:13 AM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] A strange question-) > <rant> > > How positively delightful to wait 24 hours and get a non-response like > this. This is like pulling blood out of a stone. At this point, I'll Sorry for your frustrations, but imagine the frustration of the library author after yet another bizarre compiler error on perfectly standard C++. Anyway, I think the answer was in the previous mail: Portability. In an ideal world most of this sort of macro hackery wouldn't exist. Unfortunately, boost exists in the real world... > just forget it and use something else. I do understand that Boost users > tend to be extremely advanced C++ users. For the record, I have been > programming in C++ for well over 10 years and still get confused at > some of the things you do. I am questioning and not understanding your > approach at all. Why? Well, lets look at Stroustrup, 3rd edition page > 160 "Macros are important in C, but have far fewer uses in C++. The > first rule about macros is: Don't use them if you don't have to. Almost > every macro demonstrates a flaw in the program, or the programmer." > Then "avoid macros." Now, I'm sure I'm missing your good reason but there you > go. To me, macros are an ugly legacy from C and render C++ code > unreadable and maintainable. So, how detailed does my question have to > be? I don't understand the whole approach and why it was taken. Is that > clear enough? This viewpoint is just fine if you are creating a library for one platform and compiler. The reality of the current world is that many supposedly standard features of C++ or parts of the standard library are not correct on many of the most common compilers. As a result, if you write a library 'to the standard' it might not get used much since it won't compile or work correctly for most people. In addition, many boost libraries push compilers to the limits and thus for some boost libraries the situation is even more severe. The result is that many boost libraries use various macro techniques to create portable code. Looking ahead a few years most of this will hopefully disappear. HTH, Jeff Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! <http://docs.yahoo.com/info/terms/> Terms of Service. [Non-text portions of this message have been removed] Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

1 0

RE: [Boost-Users] A strange question-)
by Garriss, Michael 14 Nov '02

14 Nov '02

Keep in mind that Aleksey doesn't get paid for this and he answered your mail on his "free" time. Cut him some slack! I thought his answers for well written. -Mike Garriss -----Original Message----- From: Sam Gentile [mailto:ManagedCode@attbi.com] Sent: Thursday, November 14, 2002 9:29 AM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] A strange question-) Well at least you gave somewhat of an answer. I still want to understand how those particular macros give that portability. Sam Gentile .NET Consultant ManagedCode(a)nospam.attbi.com http://www.samgentile.com http://radio.weblogs.com/0105852/ -----Original Message----- From: Jeff Garland [mailto:jeff@crystalclearsoftware.com] Sent: Thursday, November 14, 2002 11:13 AM To: Boost-Users(a)yahoogroups.com Subject: RE: [Boost-Users] A strange question-) > <rant> > > How positively delightful to wait 24 hours and get a non-response like > this. This is like pulling blood out of a stone. At this point, I'll Sorry for your frustrations, but imagine the frustration of the library author after yet another bizarre compiler error on perfectly standard C++. Anyway, I think the answer was in the previous mail: Portability. In an ideal world most of this sort of macro hackery wouldn't exist. Unfortunately, boost exists in the real world... > just forget it and use something else. I do understand that Boost users > tend to be extremely advanced C++ users. For the record, I have been > programming in C++ for well over 10 years and still get confused at > some of the things you do. I am questioning and not understanding your > approach at all. Why? Well, lets look at Stroustrup, 3rd edition page > 160 "Macros are important in C, but have far fewer uses in C++. The > first rule about macros is: Don't use them if you don't have to. Almost > every macro demonstrates a flaw in the program, or the programmer." > Then "avoid macros." Now, I'm sure I'm missing your good reason but there you > go. To me, macros are an ugly legacy from C and render C++ code > unreadable and maintainable. So, how detailed does my question have to > be? I don't understand the whole approach and why it was taken. Is that > clear enough? This viewpoint is just fine if you are creating a library for one platform and compiler. The reality of the current world is that many supposedly standard features of C++ or parts of the standard library are not correct on many of the most common compilers. As a result, if you write a library 'to the standard' it might not get used much since it won't compile or work correctly for most people. In addition, many boost libraries push compilers to the limits and thus for some boost libraries the situation is even more severe. The result is that many boost libraries use various macro techniques to create portable code. Looking ahead a few years most of this will hopefully disappear. HTH, Jeff Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.

2 1

max, min, VC++6 and 7
by soulofsealion 14 Nov '02

14 Nov '02

Could someone provide me a brief explanation as to why max and min are redefined in \boost\config\suffix.hpp and \boost\config\platform\win32.hpp. It appears that the reason is that the max and min macros defined in windef.h are not type safe. Also, in user application code, would it be recommended to always use the _MAX and _MIN macros in VC++ 6 and 7 so that the STL implementations are always used, and just reserve explicit max and min for the Boost library code?

1 0

Re: Is MTL alive?
by Paul C. Leopardi 14 Nov '02

14 Nov '02

Alexei, See this thread on the MTL-devel mailing list archive: http://www.osl.iu.edu/MailArchives/mtl-devel/msg00435.php As you can see from the mailing list and the download area, there has not been much developer activity since September. There is also an MTL 3 prototype called MXTL at: http://www.mpi.nd.edu/~jsiek/mxtl.html See http://www.osl.iu.edu/MailArchives/mtl-devel/msg00373.php and http://lists.boost.org/MailArchives/boost/msg10435.php Best regards

1 0

Help with boost::function and boost::bind
by electricsnark 14 Nov '02

14 Nov '02

I need to make a registry of callback functions, which are in the form of member functions of objects of various types. ----------- code snippet ----------- class T1 { public: void CallBackFcn(); }; ... class Registry { public: template <typename T> void registerFcn (void (T::*updFcn)(), T* obj ); private: vector< boost::function<void>* > fcnvec; }; template <typename T> void Registry::registerFcn(void (T::*updFcn)(), T* obj) { boost::function<void> *fp = new boost::function<void> ( boost::bind(updFcn,obj) ); fcnvec.push_back( fp ); } main() { .... T1 *pt = new T1; p_Registry->registerFcn(&T1::CallBackFcn, pt); } ----------------------------------------------------- However, before adding the boost::function to the vector, I want to make sure that the callback function isn't already in there. Unfortunately, I can't just look at value of the pointer fp - I need to get to the address of the actual callback function that is to be executed. But I can't figure out how to get there. Any help appreciated.

2 1

Getting a matrix to the power of n
by agiatojon 14 Nov '02

14 Nov '02

Hello all, I am working with a formula which requires me to get the result of a matrix to the power of n (i.e. pow(matrix, n)) but as expected, the <cmath> function pow() is unable to convert from type double to matrix. Does the matrix library have this sort of functionality built in, or maybe some other part of boost? Thanks! Jon Agiato JonAgiato(a)nyc.rr.com

1 0

Problem with matrix_expressions
by agiatojon 14 Nov '02

14 Nov '02

Hello all, I am trying to compile the following code snippet from the documentation of matrix_expressions in which two matrices are used to display the use of addition and subtraction operations. I am not really sure how to post the error messages as there are literally hundreds of them, so here is the code as I am am pretty sure this is going to be one of those well known bugs kind of things. Compiled using VS.NET, debug mode. #include <iostream> #include <boost/numeric/ublas/matrix_expression.hpp> int main() { using namespace boost::numeric::ublas; matrix<double> m1(3, 3), m2(3, 3); for(int i = 0; i < std::min(m1.size1(), m2.size1()); ++i) for(int j = 0; j < std::min(m1.size2(), m2.size2()); ++j) m1(i, j) = m2(i, j) = 3 * i + j; std::cout << m1 + m2 << std::endl; std::cout << m1 - m2 << std::endl; std::cin.get(); return EXIT_SUCCESS; } Thanks! Jon Agiato JonAgiato(a)nyc.rr.com

3 2

ublas/config.hpp compliation error
by Michael Pagels 14 Nov '02

14 Nov '02

This is my first attempt at using ublas, here's the problem -- g++ -DHAVE_CONFIG_H -I. -I.. -I../sg -I../shared -I../include -O2 -g -c Linearity.C -o Linearity.o In file included from ../include/boost/numeric/ublas/matrix.hpp:20, from Linearity.C:16: ../include/boost/numeric/ublas/config.hpp:375: parse error before `,' token ../include/boost/numeric/ublas/config.hpp:381: parse error before `,' token ../include/boost/numeric/ublas/config.hpp:387: parse error before `,' token ../include/boost/numeric/ublas/config.hpp:401: too many template parameter lists in declaration of `typename V::size_type boost::numeric::ublas::num_elements(const V&)' ../include/boost/numeric/ublas/config.hpp:401: syntax error before `{' token ../include/boost/numeric/ublas/config.hpp:404: parse error before `>' token ../include/boost/numeric/ublas/config.hpp:408: parse error before `>' token ../include/boost/numeric/ublas/config.hpp:413: too many template parameter lists in declaration of `typename MV::size_type num_non_zeros(const MV&)' ../include/boost/numeric/ublas/config.hpp:413: syntax error before `{' token /usr/include/g++-v3/bits/std_cmath.h:69: confused by earlier errors, bailing out I'm using boost_1_29_0, and gcc 3.0.4 under Linux. I reviewed the newsgroup and didn't see this problem mentioned, so I'm sure it's something obvious to the experienced. Thanks

3 2