September 2003 - Boost-users

Test
by Victor A. Wagner, Jr. 13 Sep '03

13 Sep '03

I haven't received anything in over a week, this is just a test of the address, please ignore. Victor A. Wagner Jr. http://rudbek.com The five most dangerous words in the English language: "There oughta be a law"

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Re: copy_if
by Witz 13 Sep '03

13 Sep '03

You can find an implementation of copy_if in Boost Wiki here: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?STLAlgorithm… An extension that i find useful is the following: template<class II, class OI, class PRED> std::pair<II,OI> copy_if(II ibegin, II iend, OI obegin, OI oend, PRED p) { for(; ibegin != iend; ++ibegin) { if(p(*ibegin)) { *obegin = *ibegin; if(++obegin == oend) break; } } return std::make_pair(ibegin, obegin); } Here we have a finite sized sink. Items are copied from the source if they satisfy the condition and if there is room left in the sink. The positions reached are returned on termination of the algorithm. Witz

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Documentation links don't
by ygor＠comcast.net 13 Sep '03

13 Sep '03

The links for PDF/HTML documentation do not work. Thanks.

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RE: [Boost-users] Re: tupl::get bag
by Ben Hutchings 12 Sep '03

12 Sep '03

nagual <nagual(a)promsoft.ru> wrote: <snip> > I correct line 12 & 13: > > tie(i1, i2, i3, c1, c2, c3).template get<num>() = t; > cout<<tie(i1, i2, i3, c1, c2, c3).template get<num>()<<endl; > > g++ (GCC) v 3.2.2 now compile ok. > > But cl (MSVC) v 13.00.9466 output not change. ;-c The problem there must be something else. VC++ 7.1 accepts the code with or without "template".

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copy_if
by Mr Zenaan Harkness 12 Sep '03

12 Sep '03

Does boost have an implementation of copy_if that I can't find yet? Just wondering, because it is an algorithm that, according to both stroustrup and o'rielly, should have been part of the standard but was essentially accidentally forgotten. Surely this (and possibly other necessary additions) would be part of an boost algorithm library, even if only one or two functions... I need copy_if, both these books I have say it's one of "the first generic algorithm that most programmers will probably write", so where is it? ??? (Yes, I can type it in, but boost is supposed to fill in the blanks, yes?) tia zen

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boost::char_separator enhancement (or, how do I do it myself)
by Mr Zenaan Harkness 12 Sep '03

12 Sep '03

I'm teaching myself C++, and want to tokenize my stream, using boost::tokenizer. I want to be able to optionally tokenize with or without including the delimiter character - this is supported. However: the delimiter character, if included, becomes its own token. I want an option to have the delimiter character be part of the previous token (which is what makes sense for the processing I am doing on my files). ??? ta zen

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Boost's pool implementation
by Thomas Harning 11 Sep '03

11 Sep '03

First off, I think the Boost pool is a great tool and for me has been one of the most useful of Boost's libraries. I have run into a problem however, due to the pool's usage of "malloc" and "free" as the names of functions. The problem is that I want to debug memory usage in my program and catch memory leaks, but using the leak detection in Visual Studio 7.1 for the CRT creates a macro for malloc and free, which conflicts with the pool's malloc and free and makes a general mess. Is there any better memory debug library/tools out there that are free and can get the line/file that the memory allocation occurred and the size perhaps and possibly a portion of the contained data as a character string? Perhaps I could write up a patch to rename the malloc and free from the boost pool [though I see that would be quite a pain to the existing users of boost's pool since code would have to be rewritten with whatever function is added]. Thanks. Thomas Harning Jr.

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boost::pool base class new override
by Rodrigo Serafim 11 Sep '03

11 Sep '03

hi first question: where on earth was boost while I was doing my last year project? just thinking of the amount of trouble I could have saved if I knew about it... makes me bang my head against several walls ;) Well, I starter looking towards memory managment with other eyes after 90% of my bugs being directly originated form it. So after looking on the boost memory library a question popped: how can I use smart pointers and pool toguether. In particular intrusive pointers and/or pool, being the "and/or" essencial. If i have class C all made and ready and now I want it work with smart pointers i just have to make a base class RefCount, use multiple inheritance to contruct C_RC and i can have both things. Problem is, now i want to use it in pool too, but my base class RefCount calls delete. My solution; make yet another base class Poolable and override new and delete there. Well to my surprise it worked but only in very special cases. I have to use pool<> and cant use object_pool<C_RC_P> it crashes. Also it only works in MSVC6 in Release, in Debug it crashes. In a nutshell, my questions: - Is object_pool->malloc / free diferent in semantics from pool->malloc / free ? - I dont mind using pool<> but doing pool<>(sizeof(C_RC_P)) isnt that typesafe, can I make it? - Why does it crash in debug ? I send the code in attatchement. sorry abount the lengthy mail, too many question, too little time Thanks, Rodrigo Serafim

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RE: [Boost-users] tupl::get bag
by Ben Hutchings 11 Sep '03

11 Sep '03

nagual <nagual(a)promsoft.ru> wrote: > I write example code for tuples::tuple::get use tuples::tie. > If compile icl (Intel C++) v 7.1 or bcc32 (Borland) v 5.6.4 all ok, > but if compile g++ (GCC) v 3.2.2 or cl (MSVC) v 13.00.9466 - > i have eror. > ;-c > I need to use it in MSVC. > Help me! <snip> Older compilers performed only minimal parsing of templates before they were instantiated, but the standard says they must do more parsing. This requires that you tell them which dependent names (names of things that depend on a template parameter) are being used as type or template names. You need to put the keyword "template" in front of "get<num>" so that the compiler can parse it correctly. Ben.

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2D Shared Array
by Kevin J. Menard, Jr. 11 Sep '03

11 Sep '03

Hi, Is it possible to build a shared_array of shared_arrays? I would imagine there must be away, but I haven't been so successful at my attempts to find it :-/ I'm working on converting an existing project over to the boost smart pointer library. We've been using dynamically allocated 2D arrays to hold points in a matrix, and would like to take advantage of the automatic clean-up that the boost smart pointers can provide. That's why I would like to make a shared_array of shared_arrays of some data type. Any help would be appreciated. And if I'm approaching this all wrong, please let me know. I'm open to suggestions for other ideas, so long as the individual points can still be referenced in the form of: point[row][col]. Thanks, Kevin

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