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[BGL] using Borland C++Builder 5
by Alex Henderson 17 Jun '02

17 Jun '02

Hi, I had a problem compiling both the test file (libs/graph/test/graph.cpp) and the first example (libs/graph/example/file_dependencies.cpp) of the BGL and traced the problem to the support for tuples. The offending line is line 40 of boost/tuple/tuple.hpp which incorporates tuples::get into the boost namespace. Commenting out this line allows the files above to compile and run OK. Leaving it in invokes an internal compiler error. The test file for tuples works OK with Builder 5 and so I guess there's a dependency somewhere. The question is - if I comment out this line am I going to get hit with problems elsewhere in the BGL? I'm new to the BGL and don't know whether the whole thing is built on the abilities of tuples. [Using boost_1_28_0, BCC5 sp1, Win2000 sp2] Thanks for any thoughts. Alex

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RE: [Boost-Users] MS VS 6: passing boost::shared_ptr<T> to a dll function
by Smith, Eric V. 16 Jun '02

16 Jun '02

How about some sample code? It's hard to help if we don't know exactly what you're trying to do. > -----Original Message----- > From: lognez [mailto:corno@dds.nl] > I am trying to pass a smart pointer (boost::shared_ptr<T>) as an > argument to > a function that is implemented by a dll and called by an executable, > but > whenever I execute the application, it goes into a loop, no matter > what the > type of T is. When the function is implemented in the exe or > when the function is called from inside the dll it works > fine. Does anybody have a clue what could be happening? BTW, > I'm not implicating a bug in boost, I know that it could as well > be a > MS VC++ bug but I would just like to know how this comes and how I > can solve > it.

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Re: Static power() function, to add in common_factor
by Daryle Walker 14 Jun '02

14 Jun '02

on 6/12/02 12:11 AM, ravioli(a)softhome.net wrote: > Is there an interest into having a power() template calculating the N-th power > of any number, when N is known at compile-time ?t uses the algorithm of the > STL power function(), and runs between two or three times faster, and maybe > could be of interest in the " <boost/math/common_factor.hpp> which provides > run-time and compile-time evaluation of the greatest common divisor (GCD) or > least common multiple (LCM) Proposals for new libraries usually go to the regular Boost list, not this one. Besides that: What would this have to do with the common-factor library? I've never heard of a function called "power". Is it a STL function that didn't get into the standard? Are there any docs for it? How do you know what algorithm it uses? > It simply works this way, for example to have PI at exponent three : > double a = power_const<3>( 3.14159) > > As the single include file is very short, please apologize if I give it > straight on, just to save your time and to have an idea how badly you judge my > poor code ;) [TRUNCATE code] I don't think your implementation will work for negative exponents. -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT mac DOT com

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Dynamic Bitset formal review - half way point
by Mat Marcus 14 Jun '02

14 Jun '02

Reminder - We have just past the half way point for the formal review of dynamic bitset. So far we have: 1 formal yes vote 1 formal no vote Discussion regarding iterators for dynamic bitset and comparison to vector<bool>. Some minor corrections and updates. I would like to see more formal reviews (including a yes or no vote) before the review period ends on the 17th. Thanks, Mat ##### > The formal review of Dynamic Bitset by Chuck Alison and > Jeremy Siek will commence today Saturday June 8th and run > through Monday, June 17th. > > The library is currently available at > <http://groups.yahoo.com/group/boost/files/dyn_bitset.tar.gz> > > > Below is an excerpt from the library's documentation: > > The dyn_bitset class represents a set of bits. It provides > accesses to the value of individual bits via an operator[] > and provides all of the bitwise operators that one can > apply to builtin integers, such as operator&& and > operator<<. The number of bits in the set is specified at > runtime via a parameter to the constructor of the > dyn_bitset. > > Each bit represents either the Boolean value true (set) or > false (reset). To toggle a bit is to change the value to > true if it is false and to false if it is true. Each bit > has a non-negative position pos. The position pos == 0 > corresponds to the least significant bit and pos == size() > - 1 is the most significant bit. When converting an > instance of dyn_bitset to or from an unsigned long, the > bit position pos corresponds to the bit value 1 << pos. > > The dyn_bitset class is nearly identical to the > std::bitset class. The difference is that the size of the > dyn_bitset (the number of bits) is specified at run-time > during the construction of a dyn_bitset object, whereas > the size of a std::bitset is specified at compile-time > through an integer template parameter. > > > For information about submitting a Formal Review, see > http://www.boost.org/more/formal_review_process.htm > > Please try out the library and comment during the review > period. Be sure to say whether or not you think the library > should be accepted by Boost. > > Compiler notes: This library has been tested using the > following compiler platforms: > > Gcc 2.95 and 3.01 > Kai C++ > Metrowerks Codewarrior 8 (beta, Mac) > Visual C++ 7.0 > Comeau > > The library presently requires template friend support and is > known not to compile with CodeWarrior 7.2 or Visual C++ 6.0. > > The library has not been tested with Borland. > > > The Formal Review manager is Mat Marcus. > > > > > > _______________________________________________ > Unsubscribe & other changes: > http://lists.boost.org/mailman/listinfo.cgi/boost-announce

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RE: [Boost-Users] shared_ptr in Borland C++ Builder
by scleary＠jerviswebb.com 12 Jun '02

12 Jun '02

> From: Craigus [mailto:yg-boost-users@m.gmane.org] > > Hi > > I'm new to using the Boost library. Welcome! :) > I have Codeguard turned on (detects memory leaks, accessing freed memory, > overwriting memory illegally and the like). When the shared_ptr object > count goes to zero operator() in checked_deleter eventually gets called. > Codeguard is reporting (in poor English): > > Method called on illegally casted object If you want to fix the problem: uncheck Project Options -> C++ -> Zero length empty class members. Then rebuild (not remake). The rest of this e-mail is just explaining what the error is and why this fixes it. Here's the problem: CodeGuard is complaining that the 'this' pointer for the checked_deleter object is invalid when its operator() is called. (The error is not reported if you uncheck the "Validate the 'this' pointer on member function entry" and rebuild). Many function objects contain no data or base classes, but operator() cannot be static, so for these function objects (including checked_deleter), a sort of unspoken convention has arisen: never use the 'this' pointer. But CodeGuard validates the 'this' pointer anyway... In common implementations of Standard C++, CG's validation would work: in the case where a function object is used as a most-derived class, it has non-zero size (according to the Standard), so 'this' would reference a "placeholder" memory location for that object. in the case where a function object is used as a base class, then the most-derived class has non-zero size, and 'this' would reference a member in some derived class. C++ Builder, however, has a non-Standard-conforming option that is on by default: Project Options -> C++ -> Zero length empty class members. This creates a "loophole" in the first case described above: in the case where a function object is used as a most-derived class *as a member of another class*, it has zero-size(!) -- and therefore if it is the last member of that class, 'this' would reference memory *after* the most-derived class. Unchecking this option allows CG's validations to work in the way described above, closing the "loophole". Happy coding! :) -Steve

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bit_iterator
by Jan Langer 12 Jun '02

12 Jun '02

hello, i do use iterator adaptor to build a bit_iterator, which return single bits of the elements of an underlying iterator. the base_type of my iterator_adaptor is std::pair <BaseIterator, unsigned int> representing the iterator and the bit position. now my iterator does not work if i adapt istreambuf_iterator because self operator++(int) { self tmp(*this); ++*this; return tmp; } of iterator_adaptor is not able to use the proxy returned by the postfix increment of the input iterator. now i searched the archive and found in: Subject: Re: [boost] (infinite) sequences using recurrence relations From: Corwin Joy < cjoy@xxxx > Date: Fri, 10 Aug 2001 01:21:28 -0500 the following sentence: >In table 72, p. 511 of the standard you will notice something weird about >the postfix increment operator: >Namely, it is specified as (void)r++. >In other words, unlike all other standard iterator types, an input iterator >is not required to return a copy of its old value! but this would mean that the expression *i++ is wrong in most cases. is there a trick to make iterator_adaptor also handle this case or shall i hope that nobody types *i++ with my bit_iterator based on such an input iterator, or did i understand something incorrectly? regards -- jan langer ... jan(a)langernetz.de "pi ist genau drei"

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shared_ptr in Borland C++ Builder
by Craigus 12 Jun '02

12 Jun '02

Hi I'm new to using the Boost library. I'm using the shared_ptr because I can't do what I want to do with the std::auto_ptr (which is to have them stored in other STL containers). I ran into the following problem in C++ Builder 5, patch 1- I have Codeguard turned on (detects memory leaks, accessing freed memory, overwriting memory illegally and the like). When the shared_ptr object count goes to zero operator() in checked_deleter eventually gets called. Codeguard is reporting (in poor English): Method called on illegally casted object It doesn't matter what type the shared_ptr holds. I even tried a console program that contains only the following line (apart from return 0; of course :-): boost::shared_ptr< int > tmp( new int ); As soon as that object goes out of scope it is destroyed and operator() is called as I indicated above and Codeguard reports the error. Has anyone else seen this behaviour ? I was originally using Boost 1.27, which gave me the same error when I used the reset method. I downloaded 1.28 and that went away so that now it's only happening when the actual shared_ptr object is destroyed. I don't have much idea of what's going on inside the shared_ptr, so I don't even know where to start looking. Any help will be much appreciated. Thanks Craigus

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Re: Re: How to use Iterator Adaptors?
by David Abrahams 12 Jun '02

12 Jun '02

"Duane Murphy" <duanemurphy(a)mac.com> wrote in message news:20020610181043.12388@mail.murphyslogic.com... > --- At Tue, 4 Jun 2002 13:02:08 +0100, Keith MacDonald wrote: > > >> So, what is the "normal" way of creating an iterator out of thin air as > >> it were? > > > >That was the question in my mind, which the first sentence of the Iterator > >Adaptors documentation led me to hope it would answer: "The Iterator Adaptor > >library allows you transform an arbitrary ``base'' type into a > >standard-conforming iterator". If the base type is a container, how do you > >do it? > > Keith, > Your email was delayed in my queue for some reason. Were you able to > figure out how to do an iterator from a container from the discussion > between Dave Abrahms and myself? Well, of course you have to think about what data the iterator will need in order to do the iteration. The Base type can't be just a container if you want the iterator to traverse the container's elements -- you need to store some indication of the position within the container -- e.g. a node pointer, and index, or an interator -- as (part of) the Base type. -Dave

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[BGL]
by Angelique Michaut 12 Jun '02

12 Jun '02

Hello, I use the BGL to read a graphviz file and I do a depth_first_search on the graph. I would like to determine the fontname (times-roman for example) the fontcolor (black for example) and the position of each node when the depth_first_search is done. Could you help me? Thinks

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How to use Iterator Adaptors?
by keithmac66 11 Jun '02

11 Jun '02

Hi, I'm struggling to understand how to use Iterator Adaptors, due to a lack of simple examples. This is disappointing, given that supposedly "Using iterator_adaptor, you can easily implement an iterator class" (www.boost.org/libs/utility/iterator_adaptors.htm) Can anyone help, by explaining how to implement a random access iterator for a custom collection class? e.g.: template <class T> class DumbCollection { public: DumbCollection(T data[10]) { for (int i = 0; i < 10; i++) m_data[i] = data[i]; } iterator begin(); iterator end(); private: T m_data[10]; }; Thanks, Keith

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