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[Boost-bugs] [ boost-Support Requests-1231445 ] lambda vs pure virtual functions
by SourceForge.net 02 Jul '05

02 Jul '05

Support Requests item #1231445, was opened at 2005-07-02 14:09 Message generated for change (Tracker Item Submitted) made by Item Submitter You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1231445&group_… Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: None Group: None Status: Open Resolution: None Priority: 5 Submitted By: SP (sw_creator) Assigned to: Nobody/Anonymous (nobody) Summary: lambda vs pure virtual functions Initial Comment: Hello all ! i tried to complile this code: ----------------------- namespace Filter{ class ResultType {...}; class SubExpression { public: virtual ResultType Result()=0; }; typedef boost::shared_ptr<SubExpression> SPtrSubExpression; ............ void F() { namespace la=boost::lambda; ResultType r; vector<SPtrSubExpression> v; .................................. vector<SPtrSubExpression>::const_iterator i=find_if(v.begin(), v.end(), la::bind(&SubExpression::Result, *la::_1)==r); } } ------------------------- and I received error: c:\Program Files\boost-1-32-0\boost\tuple\detail\tuple_basic.hpp(419): error C2259: 'Filter::SubExpression' : cannot instantiate abstract class complier :VC++ 7.1 boost 1.32.0 what's wrong? thanks. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=207586&aid=1231445&group_… ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Boost-bugs mailing list Boost-bugs(a)lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/boost-bugs

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Re: [boost] Library Proposal: Boost.Geom 2D and 3D GeometricPrimi tives
by Martin Bonner 02 Jul '05

02 Jul '05

----Original Message---- From: Anis Benyelloul [mailto:benyelloul@mailbolt.com] > " There is no such a thing as a 2D point, There is even no such a > thing as 2D, the world is 3D, and all points are 3D. Now, some point > are always located on Z=0 plan and don't need to actually store their > Z attribute, we call them 2D points." Actually one of the current popular physical theories is that the world is 11D (or is it 15?). [Snip] >> Mixing 2D and 3D points doesnt actually happen in my experience. >> They live in separate spaces. > Like I say, 2D points are elements of IRxIR which is U which is part > of IRxIRxIR which is the set of all 3D points. It just a matter of > how you look at things .. Yes, but insisting that people consider 2D points a subset of 3D points (rather than a different concept which is isomorphic with a subset of 3D points), is probably a mistake. -- Martin Bonner Martin.Bonner(a)Pitechnology.com Pi Technology, Milton Hall, Ely Road, Milton, Cambridge, CB4 6WZ, ENGLAND Tel: +44 (0)1223 441434

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Re: [boost] Library Proposal: Boost.Geom 2D and 3D GeometricPrimitives
by Hickerson, David A 02 Jul '05

02 Jul '05

I could not find the original message to look at the proposed code, is it on the web site some where? Here are my requirements for a Geometry library. 1. The primitives integrate with translational and rotational elements, such as homogenous transforms (4x4 matrices), quaterions, Euler angles, and translation vectors. 2. The translationals and rotation elements convert to one another where applicable. The rotational part of the homogenous transform convert to and from a rotational quaterion and to and from Euler angles, or quaterion to Euler angles. The translation parts can be extracted and set in the homogenous transform. 3. At a minimum, OpenGL array extraction from homogenous tranforms, points, and shapes. A float array in the order that OpenGL expects for these elements. Support for DirectX, and others would be good. I have done some of this in the library I wrote in 97. Dave -----Original Message----- From: Joel de Guzman [mailto:joel@boost-consulting.com] Sent: Tuesday, June 28, 2005 11:02 AM To: boost(a)lists.boost.org Subject: Re: [boost] Library Proposal: Boost.Geom 2D and 3D GeometricPrimitives Anis Benyelloul wrote: > Joel de Guzman <joel <at> boost-consulting.com> writes: > > >>How do you plan to implement your regions? If your Points can use >>native platform points, I assume your regions can also use native >>platform regions? Or are we talking about different things? I'm >>interested on how you can make it use the Macintosh classic Region, >>for example. > > > Well, let me think of it.... What is a region ? A collection of (non- > overlapping ?) boxes. Now what is a collection of boxes ? > - std::vector<box> > - boost::array<box, 20> > - box ; // Note: a single box ! > - XRegion ;// Maybe some pre-existing region object in other libraries > > As you see, the problem is quite the same: for one abstraction > (region) being > able to choose among many implementations, and just "plug" them in some > convenient wrapper class. > > Actually, I haven't studied much the subject, but it doesn't seem of > extrem > complexity ... Well, not so fast. Been there done that. The problem is how to interoperate on two regions. Example: I need to XOR a YRegion with a MacRegion. The thing is, a classic mac region is an opaque data type (actually, it's not implemented as a collection of boxes). The mere fact that it is opaque makes it impossible to even copy a mac region to a YRegion. Cheers, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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Re: [boost] Library Proposal: Boost.Geom 2D and3DGeometricPrimitives
by Hickerson, David A 02 Jul '05

02 Jul '05

I put it on the Boost sand box as vec.zip . The algorithms work and it ran on Windows using Borland C++ 4.5/5.0, MS C++ 6.0, and SGI Irix 6.2 with I think the 7.2 compiler. I added a readme.txt to it to explain a little bit about it and ran CppDoc against too, don't know how useful that was though. Dave -----Original Message----- From: Andy Little [mailto:andy@servocomm.freeserve.co.uk] Sent: Thursday, June 30, 2005 3:52 PM To: boost(a)lists.boost.org Subject: Re: [boost] Library Proposal: Boost.Geom 2D and3DGeometricPrimitives "Hickerson, David A" <david.a.hickerson(a)boeing.com> wrote >I will locate the library this evening and upload it. One this about it >was I developed it before I saw Boost and had developed my own >conventions. I did this as part of a thesis work in Robotics and will I >was working for a 3D Vis company. There are references to robot >convension and a graphics convension. This is because the robotics and >engineering use a column vector notation and the graphics community >uses a row vector convension or least OpenGL does. > > If those involved with Boost are interested, I would like to donate > the code for use in developing the capabilities here. I'd be keen to see it too. Andy Little _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost

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Re: [boost] [home page] Marketing?
by BRIDGES Dick 01 Jul '05

01 Jul '05

> -----Original Message----- > From: boost-bounces(a)lists.boost.org [mailto:boost-bounces@lists.boost.org] On > Behalf Of David Abrahams > Sent: Friday, July 01, 2005 11:29 AM > To: boost(a)lists.boost.org > Subject: Re: [boost] [home page] Marketing? > > Peter Simons <simons(a)cryp.to> writes: > > > Martin Wille writes: > > > > > Sorry disappoint you, but, frankly, "So download" <insert > > > product here> "and start enjoying it" is exactly the kind > > > of text I _never_ want to read in anything supposed to > > > provide information. > > > > I wanted to say the say the exact same thing, Martin. I couldn't > > care less about having a link to "collected appeals to authority" > > on the front page. I use the Boost libraries for technical > > reasons, not because Bjarne Stroustrup (reportedly) uttered a > > fancy one-liner about them at one point. > > You don't think we'll draw new users because Scott Meyers has > recommended that people familiarize themselves with Boost? I think it might depend on the market and the particular segments the home page is attempting to gain. I'm just a programmer, but when I want to use Boost libraries, I have to sell the idea to certain groups and the home page helps. (I'll leave out the programmers we'd like to "convert".) I have to sell the Boost libraries to our legal department. Most of their experience involves the GNU GPL. Oh good. Good thing I have that License link. Even if the Acknowledgements at the bottom of the License page cannot be moved to the top and put it in 72 point type, Harvard Law still sells. I have to sell the Boost libraries to mid-level managers. It's been a while since they've fired up a compiler but they're pretty good with project management software. You [plural, no one and everyone] may not realize it, but the mailing list links and a quick tour through current threads screams "SUPPORT". Boost "people" are not only helpful, they are nice! That learning curve might not be too steep after all. I have to sell the Boost libraries to QA, version control, build-meister, etc. What about quality, standards and backward compatibility? The links to reviews take care of most of those questions. Charity work performed by some Boost members for a certain international organization doesn't go unnoticed either. Now if our own code were that good... ;) <point> I have to sell the Boost libraries to what I'll call "non-programming other management" (includes Sales and Marketing). They tend to be what I'll call "conservative": if they're not familiar with it, they tend to be suspicious. They created NIH. [My attitude may show here.] I don't need 50 million flies but a few dozen well-known examples would help to increase name recognition *a lot*. I have this dream that someday one of them asks: "Hey, can we tell *OUR* customers we use the Boost libraries?" </point> BTW: The only segment I've never had to sell Boost to are those that use their C++ compilers to compile C++. Just my $.02 As always, thanks to all for the code and the mentoring. Dick Bridges

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Re: [boost] [serialization] Notes from a new boost user
by Michael Behrns-Miller 01 Jul '05

01 Jul '05

> David Abrahams wrote: >> "Michael Behrns-Miller" <m(a)thedigitalmachine.com> writes: >> >>> 2) The new "const required to save" restriction bit me, took a day or >>> two to work through the mailing list and #boost to figure out the >>> problem. Is >> >> Did it prevent a bug, or did it just cost you 2 days of your valuable >> time? > > Were you not tempted to just use "const_cast"? Why not? I temporarily tried it and got it to work, but that wasn't an acceptable solution to me. I hate casting, immediately makes me reassess the design. Which I did, which led me to the answer. :P I expected to have ramp-up time with boost. I probably spent a day fiddling with bjam, a half day figuring out to include boost libraries, and a day or two on the const issue. Not full days, just poking around in my spare time. I got everything working under vc71 and gcc 3.3.5 way before getting frustrated, so I was happy. Also, to be fair to you, I was using a verbatim copy of the demo code to start, which I believe needs updating. I was working from documentation that didn't cover the const issue. With those two improvements, I would have been better off. But I am not foolish enough to pretend I have the answer to the const issue, especially given there are many current serialization users. Just providing some feedback. <ducks and runs> > Whenever I do include a BOOST_STATIC_ASSERT that a library user might be > expected to trip on, I include comments at that point which describes the > problem and hopefully a helpful course of action. When I build in my > environment (VC 7.1) and double click on the error message, the > BOOST_STATIC_ASSERT pops up and right there is the comment explaining it. > To me, this seems pretty good and I would hope that this would minimize > the time a user has to spend looking for sources to these problems. In > fact, I have received mail from users that have remarked upon exactly > this feature/practice as being very helpful in understanding these other > wise very subtle errors. By far the best one is when one uses an > xml_archive to serialize something which doesn't have a variable name > attached. It pops a STATIC_ASSERT and the comment right there is the > comment describing what one is doing wrong. I agree, that's where I started when figuring it out, looking at the error line, which clued me in. Thanks again.

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[serialization] Notes from a new boost user
by Michael Behrns-Miller 01 Jul '05

01 Jul '05

> I've become very skeptical of my ability to predict how other programmers > are going to address things. I'm willing to wait and see. > > So I'm anxious to see where this goes. If in fact we do get a wave of > users with problems, I'll be forced to modify my point of view in the > face of the facts. If (almost) no one complains (perhaps unlikely) then > there will be no issue. If there are a fair number of complaints - but > it turns out that a significant portion are due to real mistakes - we > might be in for another debate. But given more data, I would expect it > to be of a different character. If it turns out (almost) none of the > cases are real problems, then I'll have to accept as a fact that its a > bad idea. As a new boost user I thought I would humbly submit some feedback. Forgive me if I missed nuances of the existing debates. 1) I love the serialization library, I'm sure many of us have done similar code before, and it's great to see work towards a standardized solution. Really useful, thanks Robert! 2) The new "const required to save" restriction bit me, took a day or two to work through the mailing list and #boost to figure out the problem. Is there a way to make the end-of-the-chain error message (`boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value') more clear? I would rate the severity of the difficulty a 2 or 3 out of 10, from a new user's perspective. It seemed intuitive enough once I understood the requirement. Putting the serialization save calls within a const save(archive) function of the object being serialized made it a non-issue for me. I haven't used it enough to say I won't run into the const issue again, but at least I know about it now. 3) I realize I can split serialize() into separate load/save functions. However, I appreciate the recommendation to use one serialize() function, where the load/save order is easier to maintain. However again, I absolutely need (I think :>) to know, within that function, if I am loading or saving. It's the only way I can efficiently handle versioning or handle dynamic allocations, and still use one serialize() function, as far as I can tell. Bottom line: I now have isSaving(archive)/isLoading(archive) functions, can these be added to the library? Or am I approaching this wrong? As I've said, I'm brand new at this. I'm providing this feedback for two reasons: to give you an idea of what I ran into as a new user, and to get suggestions on anything I'm approaching in the wrong way. Thanks again boost.

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[serialization] Notes from a new boost user
by Michael Behrns-Miller 01 Jul '05

01 Jul '05

> I've become very skeptical of my ability to predict how other programmers > are going to address things. I'm willing to wait and see. > > So I'm anxious to see where this goes. If in fact we do get a wave of > users with problems, I'll be forced to modify my point of view in the > face of the facts. If (almost) no one complains (perhaps unlikely) then > there will be no issue. If there are a fair number of complaints - but > it turns out that a significant portion are due to real mistakes - we > might be in for another debate. But given more data, I would expect it > to be of a different character. If it turns out (almost) none of the > cases are real problems, then I'll have to accept as a fact that its a > bad idea. As a new boost user I thought I would humbly submit some feedback. Forgive me if I missed nuances of the existing debates. 1) I love the serialization library, I'm sure many of us have done similar code before, and it's great to see work towards a standardized solution. Really useful, thanks Robert! 2) The new "const required to save" restriction bit me, took a day or two to work through the mailing list and #boost to figure out the problem. Is there a way to make the end-of-the-chain error message (`boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value') more clear? I would rate the severity of the difficulty a 2 or 3 out of 10, from a new user's perspective. It seemed intuitive enough once I understood the requirement. Putting the serialization save calls within a const save(archive) function of the object being serialized made it a non-issue for me. I haven't used it enough to say I won't run into the const issue again, but at least I know about it now. 3) I realize I can split serialize() into separate load/save functions. However, I appreciate the recommendation to use one serialize() function, where the load/save order is easier to maintain. However again, I absolutely need (I think :>) to know, within that function, if I am loading or saving. It's the only way I can efficiently handle versioning or handle dynamic allocations, and still use one serialize() function, as far as I can tell. Bottom line: I now have isSaving(archive)/isLoading(archive) functions, can these be added to the library? Or am I approaching this wrong? As I've said, I'm brand new at this. I'm providing this feedback for two reasons: to give you an idea of what I ran into as a new user, and to get suggestions on anything I'm approaching in the wrong way. Thanks again boost.

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Boost.Build v2 with VC8
by Johan Johansson 01 Jul '05

01 Jul '05

How do you do it? I've tried adding using msvc : 8.0 to user.config and I've tried using msvc : vc-8_0 since that didn't appear to work. At that point I got the message that the python lib wouldn't be build - but I've set both PYTHON_ROOT and PYTHON_VERSION to the satisfaction of Boost.Build v1. Can someone please tell me what to configure and the exact command line I should use to build it? I've already spent 2 hours running in circles in the docs and that doesn't seem to get me anywhere. Thanks, Johan

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[serialization] Regressions?
by Vladimir Prus 01 Jul '05

01 Jul '05

Hi Robert, I've just updated by Boost tree and run in a number of compile errors. One is pretty easy -- I've committed the attached trivial patch to split_member.hpp. Another is this: ....boost/boost/archive/detail/oserializer.hpp:551: error: incomplete type `boost::STATIC_ASSERTION_FAILURE<false>' does not have member `value' instantiated from this code of mine: ofstream ofs(av[2]); boost::archive::binary_oarchive oa(ofs); oa << *data_builder.finish(); Where 'finish' returns auto_ptr<Data>. It's looks like serialization checks if the serialized type is 'const' and if not, complains. Basically, it's some heuritic to prevent saving on-stack object (though I don't understand why it would work at al). I find this a bit too much . I have no reason whatsoever to make 'finish' return auto_ptr<const Data>. And writing oa << const_cast<const Data&>(*data_builder.finish()); looks very strange. And modifying all places where I get this error is not nice too. So, can this static assert be removed? Then, I get ambiguity in iserializer.hpp, in this code: #ifndef BOOST_NO_FUNCTION_TEMPLATE_ORDERING template<class Archive, class T> inline void load(Archive &ar, const serialization::nvp<T> &t){ load(ar, const_cast<serialization::nvp<T> &>(t)); } For some reason, both boost::archive::load and some other 'load' in 'boost' namespace (part of earlier serialization lib) that I still use are considered overload candidates. Adding explicit boost::archive:: fixes this. See attached patch. Then I get error at this code: ar << boost::lexical_cast<std::string>(*this); The error message is: error: no match for 'operator<<' in 'ar << boost::lexical_cast(Source) [with Target = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, Source = lvk::nm_model::BlockFormula]()' /space/NM/boost/boost/archive/detail/interface_oarchive.hpp:75: error: candidates are: Archive& boost::archive::detail::interface_oarchive<Archive>::operator<<(T&) [with T = std::basic_string<char, std::char_traits<char>, std::allocator<char> >, Archive = boost::archive::binary_oarchive] ...unrelated operator<< definitions snipped... Apparently, passing rvalue to "T&" does not work. Yes another attached patch fixes this issue. - Volodya

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