April 2007 - Boost-users - lists.boost.org

Failed gcc link and targets
by Douglas Linford 17 Apr '07

17 Apr '07

2 Davids, The output at the top of the compile after running: bjam "-sTOOLS=gcc" install > out.txt 2>&1 shows python errors followed by: ...found 13313 targets... ...updating 250 targets... And then throughout the compile there are a lot of link errors and FileClone operation not permitted errors. The the compile completes with a lot of skipped errors ending with: ....failed updating 110 targets... ...skipped 118 targets... ...updated 22 targets... So...the following list from the Boost site gave the order for compiling which I completed in order with my appended notes: 1. Download Boost <http://boost.org/more/getting_started.html#step1>. 2. Install Boost.Jam<http://boost.org/more/getting_started.html#step2>. ( I installed bjam to: /usr/local/bin/bjam) 3. Configure your compiler toolset<http://boost.org/more/getting_started.html#step3>. (This I did not do...I didn't know what they wanted me to do) 4. Go to Boost distribution directory<http://boost.org/more/getting_started.html#step4> . 5. Build and install<http://boost.org/more/getting_started.html#step5> . Could some of this be the result of the fact that I didn't configure my compiler? Thanks guys... Douglas

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[ptr_container]Visual C++ 2005 visualizers for ptr_container classes and boost::array
by Bill Buklis 17 Apr '07

17 Apr '07

Since I work with the ptr_container classes (especially ptr_vector and ptr_map) quite a bit (very nice library!), I found it a little frustrating attempting to debug container and iterator variables for these classes as compared with how well the std containers show up in the VC++ watch window. After some thought and experimentation I figured out how to add these classes to the VC++ visualizer so that now these objects will display almost as well as the std containers. For those of you unfamiliar with the built-in visualizer (no surprise as there is no official documentation for it), there is a text file called autoexp.dat that contains definitions on how to display custom objects in the watch window (including CString, std::string, and the standard containers). I found this very helpful blog article that explains this in more detail: http://www.virtualdub.org/blog/pivot/entry.php?id=120. The autoexp.dat file is usually located in C:\Program Files\Microsoft Visual Studio 8\Common7\Packages\Debugger. Place the visualizer code (included down below) at the end of the "visualizer" section of autoexp.dat (probably near the end of the file). Some notes: 1. ptr_vector expands outs the same way as std::vector<T*> would rather than std::vector<T>. I did it this way so you can easily see the memory address of each contained object. 2. ptr_map unfortunately doesn't expand out exactly the same as std::map<K,T*>. This is because ptr_map uses std::map<K,void*> internally and not map<K,T*>. I couldn't figure out any way to auto convert the sub-level appropriately. As a result the expanded entries only show the value objects and not KEY and VALUE (e.g. where VALUE is the "second" member). As a compromise I display the KEY elements in the preview section so that you can still see them. The preview section can be seen in two places: as a tooltip when you highlight the variable and on the first line next to the variable in the watch window. If anyone can think of a workaround or a better alternative let me know. 3. Also included is an entry for boost::array, so that these can be seen in the watch window in the same manner as a static array. Any questions? Enjoy, -- Bill -- Add the following text to autoexp.dat: ;--------------------------------------------------------------------------- --- ; boost::ptr_vector ;--------------------------------------------------------------------------- --- boost::ptr_vector<*,*>{ children ( #array ( expr: (($T1**)($c.c_._Myfirst))[$i], size : $c.c_._Mylast-$c.c_._Myfirst ) ) preview ( #( "[", $e.c_._Mylast - $e.c_._Myfirst , "](", #array ( expr : (($T1**)($c.c_._Myfirst))[$i], size : $c.c_._Mylast-$c.c_._Myfirst ), ")" ) ) } ;--------------------------------------------------------------------------- ; boost::ptr_vector::iterator ;--------------------------------------------------------------------------- boost::void_ptr_iterator<std::_Vector_iterator<*>,*>{ preview ( #( ($T2*)(*$c.iter_._Myptr) ) ) children ( #( ptr: ($T2*)(*$c.iter_._Myptr) ) ) } ;--------------------------------------------------------------------------- ; boost::ptr_set::iterator ;--------------------------------------------------------------------------- boost::void_ptr_iterator<*,*>{ preview ( #( ($T2*) $e.iter_._Ptr->_Myval) ) children ( #(ptr: ($T2*) $e.iter_._Ptr->_Myval) ) } ;--------------------------------------------------------------------------- ; boost::ptr_map ;--------------------------------------------------------------------------- boost::ptr_map<*,*,*>{ preview ( #( "[", $e.c_._Mysize, "](", #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, size : $c.c_._Mysize, left : _Left, right : _Right ) : $e._Myval.first, ")" ) ) children ( #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, size : $c.c_._Mysize, left : _Left, right : _Right ) : ($T2*)$e._Myval.second ) } ;--------------------------------------------------------------------------- ; boost::ptr_map ;--------------------------------------------------------------------------- boost::ptr_multimap<*,*,*>{ preview ( #( "[", $e.c_._Mysize, "](", #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, size : $c.c_._Mysize, left : _Left, right : _Right ) : $e._Myval.first, ")" ) ) children ( #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, size : $c.c_._Mysize, left : _Left, right : _Right ) : ($T2*)$e._Myval.second ) } boost::ptr_map_iterator<*,*,*>{ preview ( #( "(", $c.iter_._Ptr->_Myval.first, ",", ($T3*) $c.iter_._Ptr->_Myval.second, ")" ) ) children ( #( key: $c.iter_._Ptr->_Myval.first, value: ($T3*) $c.iter_._Ptr->_Myval.second, _ptr: $c.iter_ ) ) } ;--------------------------------------------------------------------------- ; boost::ptr_set ;--------------------------------------------------------------------------- boost::ptr_set<*,*>{ preview ( #( "[", $e.c_._Mysize , "](", #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, left : _Left, right : _Right, size : $c.c_._Mysize ) : ($T1*)$e._Myval, ")" ) ) children ( #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, left : _Left, right : _Right, size : $c.c_._Mysize ) : ($T1*)$e._Myval ) } ;--------------------------------------------------------------------------- ; boost::ptr_set ;--------------------------------------------------------------------------- boost::ptr_multiset<*,*>{ preview ( #( "[", $e.c_._Mysize , "](", #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, left : _Left, right : _Right, size : $c.c_._Mysize ) : ($T1*)$e._Myval, ")" ) ) children ( #tree ( head : $c.c_._Myhead->_Parent, skip : $c.c_._Myhead, left : _Left, right : _Right, size : $c.c_._Mysize ) : ($T1*)$e._Myval ) } ;--------------------------------------------------------------------------- ; boost::array ;--------------------------------------------------------------------------- boost::array<*,*>{ preview( $c.elems ) children ( #array ( expr: $c.elems[$i], size : $T2 ) ) }

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[ptr_container]Internal use of void* containers
by Bill Buklis 17 Apr '07

17 Apr '07

Internally, the ptr_container classes use a void* container to do its magic. For example, ptr_vector uses a std::vector<void*> (and similarly for ptr_map and ptr_set) Or come to think of it, I believe it's actually vector<void**> and map<KEY,void*>, respectively. I'm curious as to why? This, of course, works just fine and since it's an internal detail it doesn't really matter. I'm just curious as to why you didn't use the more obvious (and perhaps wrong) choice of vector<T*>. Note: I'm not suggesting that it be changed. Functionally I have no issues with it, naturally, as it works. But, it does make debugging a little more interesting. But, even that is easy to get around. Just curious, -- Bill --

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dereference an iterator
by Christian Holmquist 17 Apr '07

17 Apr '07

Sorry for beeing off-topic, but is there a utility in boost for dereferencing an iterator, such as the below (but that also works for boost::reference_wrapper) template<class Iterator> typename std::iterator_traits<Iterator>::reference deref(Iterator i) { return *i; } Thanks, Christian

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Deep copy of objects coupled with shared and weak pointer
by Fabian Sturm 17 Apr '07

17 Apr '07

Hi! I used the boost shared pointers for quite a while successfully but now ran into a problem I don't have a nice solution yet. I have a class A which has a vector of B classes. I now need to get from the class A to all Bs which is easy (iterating over the vector) and I need to get from any B to A (which I handle with a weak pointer) But now I need to implement a copy method to get a "real" copy of A and not a pointer to the shared instance. How would I do that? The copy also points to copies of the Bees aka. deep copy. My current solution looks like this: class A; class B; typedef boost::shared_ptr< A > A_SP; typedef boost::weak_ptr< A > A_WP; typedef boost::shared_ptr< B > B_SP; class A : public boost::enable_shared_from_this< A > { public: int x; int y; std::vector< B_SP > bees; void addB ( B_SP b ); A_SP clone (); }; class B { public: A_WP weakA; int c; B_SP clone (); }; void A::addB ( B_SP b ) { b->weakA = shared_from_this(); bees.push_back ( b ); } A_SP A::clone () { A_SP newA ( new A ); newA->x = x; newA->y = y; for ( std::vector< B_SP >::const_iterator it = bees.begin (); it != bees.end (); ++it ) { newA->addB ( (*it)->clone () ); } return newA; } B_SP B::clone () { B_SP newB ( new B ); // note I can't initialize the weak_ptr here newB->c = c; return newB; } int main() { A_SP a ( new A ); B_SP b ( new B ); a->addB ( b ); // Now make a deep copy of a A_SP newA = a->clone(); return 0; } Any ideas how this could be done more beautiful? Or more C++ish? Every help is greatly appreciated, since I still need to get accustomed to C++. Thanks a lot, Fabian

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[bind] Surprising behavior
by Christian Henning 16 Apr '07

16 Apr '07

Hi there, I'm sure it's not a bug in bind but I have found a surprising behavior when using it. In my project I have to use some old school c++ classes that use character arrays instead of std::string. The following code displays a difference when using two ways of printing those character arrays. #include <iostream> #include <string> #include <vector> #include <algorithm> #include <functional> #include <boost/bind.hpp> using namespace std; using namespace boost; class A { public: A( string name ) { strncpy( _name, name.c_str(), name.length() + 1 ); } string name() const { return _name; } private: char _name[80]; }; void print( const char* s ) { cout << s << endl; } int main(int argc, char* argv[]) { vector<A> as; as.push_back( A( "A" )); as.push_back( A( "B" )); for_each( as.begin() , as.end() , bind( &print , bind( &std::string::c_str , bind( &A::name, _1 )))); vector<A>::const_iterator it = as.begin(); vector<A>::const_iterator end = as.end(); for( ; it != end; ++it ) { cout << it->name() << endl; } return 0; } The output should be A B A B But instead it's A B The foreach loop doesn't print anything. The problem is when calling the print function the char* points to an empty string. Can somebody please enlightening, here. Thanks, Christian

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[BGL] How to use an array in bundled property?
by Shufei Fan 16 Apr '07

16 Apr '07

I defined an double array inside bundled vertex property, and have trouble finding ways of accessing it. Neither can I find any where in the document an example on it. Your input will be much appreciated! my graph is defined as follows: struct Node { double mode[3]; // this is hard to access }; struct Edge { double nPixels; unsigned short nTh; //no problem access them }; typedef boost::adjacency_list< boost::vecS, boost::vecS, boost::bidirectionalS, Node, Edge> Graph; Graph colGraph; I have no problem with accessing the 'nPixels' in Edge property, boost::property_map<Graph, double Edge::*>::type ew = get(&Edge::nPixels, *colGraph);//edge weight But I am in a great deal of trouble finding ways of accessing 'mode' in Node property. compiler error here: boost::property_map<Graph, double Node::*>::type nm = get(&Node::mode, *colGraph);//node mode error message is : //---------------------------------------------------- c:\...\xxx.cpp(236) : error C2440: 'initializing' : cannot convert from 'boost::property_map<Graph,Property>::type' to 'boost::bundle_property_map<Graph,Descriptor,Bundle,T>' with [ Graph=boost::adjacency_list<boost::vecS,boost::vecS,boost::bidirectionalS,Node, Edge>, Property=double (Node::* )[3] ] and [ Graph=Graph, Descriptor=boost::property_map<Graph,double Node::* >::descriptor, Bundle=Node, T=double ] No constructor could take the source type, or constructor overload resolution was ambiguous //---------------------------------------------------- neither the following works(I added '[3]' in the parameter list): boost::property_map<Graph, double Node::*[3]>::type nm = get(&Node::mode, *colGraph);//node mode This time errors are raised in the 'property.hpp' file, they are: //---------------------------------------------------- c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2825: 'PropertyTag::kind': cannot form a qualified name c:\Boost\include\boost-1_33_1\boost\graph\properties.hpp(198) : see reference to class template instantiation 'boost::property_kind<PropertyTag>' being compiled with [ PropertyTag=double Node::* [3] ] c:\shufei\VCProjects\edison\segm\GA.cpp(236) : see reference to class template instantiation 'boost::property_map<Graph,Property>' being compiled with [ Graph=Graph, Property=double Node::* [3] ] c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2039: 'kind' : is not a member of 'operator``global namespace''' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2146: syntax error : missing ';' before identifier 'type' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : error C2955: 'boost::type' : use of class template requires template argument list c:\Boost\include\boost-1_33_1\boost\type.hpp(14) : see declaration of 'boost::type' c:\Boost\include\boost-1_33_1\boost\pending\property.hpp(40) : fatal error C1903: unable to recover from previous error(s); stopping compilation //---------------------------------------------------- thanks, Shufei

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[test] Bug in macros when used with valarray?
by Paul Giaccone 16 Apr '07

16 Apr '07

I have a bug in my program that looks as though it might be in the macros in test. The following line gives me a segmentation fault: BOOST_CHECK_SMALL(var[a][b].first, accuracy); The variable "var" is of type boost::shared_array<std::pair<double, std::valarray<double> > >, for which memory has been allocated as follows (with variable names disguised): const unsigned int num_elements1 = /* some value */; const unsigned int num_elements2 = /* some other value */; const unsigned int num_elements3 = /* another value */; boost::shared_array<boost::shared_array<std::pair<double, std::valarray<double> > > > var_array( new boost::shared_array<std::pair<double, std::valarray<double> > >[num_elements1]); for (unsigned int a = 0; a != num_elements1; ++a) { var[a].reset(new std::pair<double, std::valarray<double> >[num_elements2]); for (b = FirstSolution; b != num_elements2; ++b) { var[a][b].second.resize(num_elements3); } } The variable "accuracy" is of type double. The variable is then passed to a test case: test_suite -> add(BOOST_TEST_CASE(boost::bind(my_test, var))); with this header: void my_test(boost::shared_array<boost::shared_array<std::pair<double, std::valarray<double> > > >& var) Within this test, "var" is passed to another function (by reference) and its contents are set. Outputting the contents shows they have been set OK (using the same array indices, note), but the segmentation fault occurs when the BOOST_CHECK_SMALL macro is used. I am using version 1.33.1 of Boost for gcc 3.2.3. I am linking against -lboost_unit_test_framework-gcc-d-1_33_1 and -lm I'm sure I have used this before without any problems in Linux. The program works perfectly well in Windows using MSVC and Boost version 1.33.1. Are there any other link flags I should be using? Is there something else I have missed? Of course, it is entirely possible that I have an array-out-of-bounds error in my code or something like that, but my diagnostics aren't picking anything like this up, and the Windows version does not report any errors with security checks enabled, and, as I say, outputting the values to std::cout does not cause a segmentation fault. Is it possible that the BOOST_CHECK_* macros don't work with std::valarray in Boost 1.33.1 for gcc 3.2.3? Thanks.

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[mpl] Fix for Visual Studio Compiler Error C1060
by Holcomb, William (Tom ) 16 Apr '07

16 Apr '07

Greetings all, I've seen posts here in the past from those who've had failures compiling (fairly complex) code that uses MPL on Microsoft Visual Studio 2003 and later. On VS 2003, the compiler says that it had an internal error, but on 2005, the error looks like this: File name: fatal error C1060: compiler is out of heap space Happily, Microsoft has published a hotfix for the problem on VS 2005, available at the following link: http://support.microsoft.com/?id=927872 The informal explanation I got is that they had a fixed size internal buffer for holding type names during compilation, and the more complex MPL code--not surprisingly--exceeded that fixed size. I don't know the nature of the fix, though. BTW and FWIW, I never got the error message when compiling in VS 2005 on a 64-bit machine. Hope this helps.

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BoostCon
by Christian Henning 16 Apr '07

16 Apr '07

Hi there, just went over the conference schedule. It looks very interesting but unfortunately I cannot make there. So, my question is if the lectures, speeches, etc. are going to be taped and available to the public, afterwards? I'm thinking of something similar to google education. I'm not sure if that is standard procedure when it comes to conferences. But heh, it's 2007! Thanks, Christian

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