November 2004 - Boost - lists.boost.org

[FSM] Patches for gcc-3.4.1
by Jürgen Hunold 08 Nov '04

08 Nov '04

Hi ! The attached patch makes the FSM-examples (except PingPong) compile with gcc-3.4.1 These are mostly scoping issues. Tested against gcc-3.3.x. Any one interested in BB.V2 Jamfiles for FSM ? Yours, Jürgen -- * Dipl.-Math. Jürgen Hunold ! Institut für Verkehrswesen, Eisenbahnbau * voice: ++49 511 762-2529 ! und -betrieb, Universität Hannover * fax : ++49 511 762-3001 ! Appelstrasse 9a, D-30167 Hannover * hunold(a)ive.uni-hannover.de ! www.ive.uni-hannover.de

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Shortcut regex notation
by Schalk_Cronje＠McAfee.com 08 Nov '04

08 Nov '04

Would anyone be interested in having a perl-like regex shortcut notation? The original idea was born during a local C++ focus group discussion. Looking further into the feasibility I thought that this might be a useful addition to Boost. Possibly something like the following (from some proof-of-concept code) using namespace boost::short_regex; std::string str("And he said: 'BLAH BLAH'"); // [1] Substitutes first occurrence and copy (calls boost::regex_replace) // perl: ($s2=$str) =~ s/(BLAH)/Hooray/; std::string s2= _s / "(BLAH)" / "Hooray" / str; // [2] Substitute globally and copy // perl: ($s2=$str) =~ s/(BLAH)/Hooray/g; s2= _s / "(BLAH)" / "Hooray" / _g / str; // [3] Substitute first occurrence in-place // perl: $str=~ s/(BLAH)/Hooray/; ~_s/ "(BLAH)" / "Hooray" / str; In the above _s and _g are special placeholder/tag objects sort of like _1,_2. Other could include _i (case-insensitive), _m (string as multiple lines) and _s (string as single line). Multiple modifiers can be added using (,) // [4] Substitute globally and copy // perl: ($s2=$str) =~ s/(BLAH)/Hooray/gi; s2= _s / "(BLAH)" / "Hooray" / (_g,_i) / str; The purpose will not be to shortcut all of the boost.regex functionality, just the common cases, as in perl or sed. Cases [1] and [3] is very close to the perl and would be easy to understand, however [2] and [4] is moving away from perl-syntax. This might be considered illegible by some.

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Re: Points vs Vectors / GUI Library Proposal for a Proposal)
by George van den Driessche 08 Nov '04

08 Nov '04

Noah Stein wrote: > >> This makes them almost the same thing. You can treat vector as a >> point, and point as a vector. Besides, we are talking about R^2, >> which is a vector space. > > Sure, there's an isomorphism between points and vectors; however, that > doesn't make them the same. There's an isomorphism between the > functions > f(x)=x and f(x)=2x; however, that does not make those two equations the > same. This could be explained by analogy with C++, which more readers here might be familiar with: the difference between points and vectors is the same as the difference between C++ pointers and C++ ints. You can add a pointer to an int, or an int to a pointer, but you can't add two pointers. However, you can subtract two pointers to get an int. Likewise, it's not really meaningful to talk about the sum of two positions, but the difference between them is the vector from one to the other. Back on the subject of a GUI library: I understand the motivation - that's where wxWindows arose. And I realise that nowadays a GUI library could be done in a much more modern C++ style. But my question is: is C++ the right language? I don't want this to descend into a religious war - C++ is my favourite language, but it isn't the best language for every task. Would a higher-level, more dynamic language be more suitable for GUI work? In a perfect world, I'd do all my back-end stuff in C++ and all the front-end development in, say, Python. By doing all the GUI work in C++ instead of an interpreted language, you: a) spend a lot more time recompiling. b) can less easily tweak a running program to try out different ideas. c) have to spend a lot of effort to construct a domain-specific language (c.f Spirit; see (a)). d) probably end up with a bigger codebase. So what do you stand to gain, other than being able to write GUIs in your favourite language, as opposed to your second-favourite language? The only thing I can think of is that you don't have to worry about any bridge between languages. George

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OOPSLA Workshop...
by Tommy 08 Nov '04

08 Nov '04

Hi, a couple of months ago, I noticed an announcement in this list for Boost’s Oopsla Workshop. The topics and goals of that workshop (review position papers / libraries, discuss new library proposals, their relative merits, benefits and weaknesses, and provide feedback on initial designs) looked very interesting. So, after that event took place (Oct 25), I’ve looked out for material describing the results of that workshop - but I have not been able to find anything!? Has the results of the workshop been put together? If so, is the outcome publically available somewhere? Regards, Curious Tommy

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boost::ref simple question
by Neal D. Becker 08 Nov '04

08 Nov '04

This must be a common question. I want to use std::transform with a function object that is expensive to copy, so I want to pass by reference. I tried to use boost::ref for this, but this simple test doesn't work: struct Op { int operator() (int x) { return 1 + x;} Op() {} private: Op (const Op&); }; int main() { vector<int> x (4); vector<int> y (4); Op o; std::transform (x.begin(), x.end(), y.begin(), boost::ref(o)); } Any suggestion?

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[regex] any interest in finite automata-based regex engine?
by Vladimir Pozdyayev 08 Nov '04

08 Nov '04

Hello. Are there any plans to add finite automata-based subengine to the regex library? If there are, I can submit the algorithm/implementation of a modified nondeterministic FA which takes care of * greedy and lazy quantifiers, * eagerness of the alternation operator, * non-longest matches (`best' in the Perl-ish sense with respect to greediness/laziness/eagerness), * substring capturing. All these features being included, the time cost of a match is O(N(E+C)L), where N is the number of states, E is the average epsilon-closure size per state, C is the number of capturing parentheses, and L is the input length. As far as I know that's the lowest order of time complexity in this area (corrections are welcome)---though, of course, deterministic FA would be even faster. I suppose there's no point in adding another regex library, but being able to guarantee linear time cost in an existing one would be nice. -- Best regards, Vladimir Pozdyayev.

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Program options auto-link bug
by John Maddock 08 Nov '04

08 Nov '04

The program options library currently doesn't select the dll-import library when auto-linking to the dll build of the library - it always tries to link to the static lib. The following patch fixes the issue: $ cvs diff -u boost/program_options/config.hpp johnmaddock(a)cvs.sourceforge.net's password: Index: boost/program_options/config.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/program_options/config.hpp,v retrieving revision 1.2 diff -u -r1.2 config.hpp --- boost/program_options/config.hpp 13 Jul 2004 15:12:24 -0000 1.2 +++ boost/program_options/config.hpp 6 Nov 2004 12:37:09 -0000 @@ -20,6 +20,10 @@ // Set the name of our library, this will get undef'ed by auto_link.hpp // once it's done with it: #define BOOST_LIB_NAME boost_program_options +// tell the auto-link code to select a dll when required: +#if defined(BOOST_ALL_DYN_LINK) || defined(BOOST_PROGRAM_OPTIONS_DYN_LINK) +# define BOOST_DYN_LINK +#endif // And include the header that does the work: #include <boost/config/auto_link.hpp> OK to commit? John.

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[multi_index] regression in gcc-3.1-linux --seeminlgy MPL-related
by JOAQUIN LOPEZ MU?Z 08 Nov '04

08 Nov '04

Currently, one of the tests of Boost.MultiIndex is failing for GCC 3.1 under Linux: http://tinyurl.com/638oh The ICE happens inside boost/mpl/aux_/at_impl.hpp. This test used to work OK against the RC branch a couple of days ago. Any idea? Thank you, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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Auto-linking and getting started docs.
by John Maddock 08 Nov '04

08 Nov '04

I've added a section on auto-linking with MS-Windows compilers in the getting started docs, in the main branch only (No URL yet, cvs hasn't cycled it through yet, but it'll be at http://cvs.sourceforge.net/viewcvs.py/*checkout*/boost/boost/more/getting_s… eventually). If it looks OK, I'll commit to the release branch as well. John.

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Re: [boost] [multi_index] regression in gcc-3.1-linux --seeminlgyMPL-related
by JOAQUIN LOPEZ MU?Z 08 Nov '04

08 Nov '04

----- Mensaje original ----- De: Martin Wille <mw8329(a)yahoo.com.au> Fecha: Domingo, Noviembre 7, 2004 7:15 pm Asunto: Re: [boost] [multi_index] regression in gcc-3.1-linux -- seeminlgyMPL-related > JOAQUIN LOPEZ MU?Z wrote: > > Currently, one of the tests of Boost.MultiIndex > > is failing for GCC 3.1 under Linux: > > > > http://tinyurl.com/638oh > > > > The ICE happens inside boost/mpl/aux_/at_impl.hpp. > > > > This test used to work OK against the RC branch > > a couple of days ago. Any idea? > > Neither CVS head, nor the RC branch have been tested > against gcc 3.1 under Linux. I (re)added this compiler > because I had spare CPU time. > > I don't think gcc 3.1 is something one has to worry > about too much. I doubt it is much in use. (Either > people still stick to the even more broken gcc 3.1 > or they use gcc 3.3 or even 3.4) You're absolutely right, even my docs state that GCC 3.1 is not supported by Boost.MultiIndex. Sorry for the noise. Joaquín M López Muñoz Telefónica, Investigación y Desarrollo

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