January 2009 - Boost-users - lists.preview.boost.org

Re: [Boost-users] [Bind] How to bind?
by Max 04 Jan '09

04 Jan '09

Thank you, Watanabe. B/Rgds Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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[Proto] Using mpl::count as proto::transform
by Joel Falcou 04 Jan '09

04 Jan '09

I have a grammar with 3 kind of terminal : A,B and C. I want to have a transform that returns a mpl::int_ which is equal to the number of B terminal that appear in expression like : A(B,B,C,B,C ..) the grammar part for matching this is currently : when< function< vargarg<my_grammar> > , mpl::count< _, terminal<B> >() > alas this always return 0 and so does : when< function< vargarg<my_grammar> > , mpl::count< _, terminal<B>::type >() > as well as the same using flatten. What do I do wrong ? -- ___________________________________________ Joel Falcou - Assistant Professor PARALL Team - LRI - Universite Paris Sud XI Tel : (+33)1 69 15 66 35

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Re: [Boost-users] proto for array expressions
by Daniel Oberhoff 03 Jan '09

03 Jan '09

>> Sorry for the delay, the holidays, you know ... >> >> Daniel Oberhoff wrote: >> > On 2008-12-18 23:46:40 +0100, Eric Niebler <eric <at> boost- >> consulting.com> >> > said: >> > >> >> Daniel Oberhoff wrote: >> >>> >> >>> Now with proto I was wondering how hard it would be to build an >> et >> >>> engine for array math. Basically I am interested in general >> tensor >> >>> notation, and the resulting expressions should be iteratable >> >>> efficiently. think (advanced example): >> >>> >> >>> a_ij = b_i * (c_j - sum(d_ijk, k = [i-1,1]) >> >> >> >> I don't understand your notation. What are a_ij et. al.? >> > >> > Sorry, the underscripts where meant to be indices. So a is a 2d >> array, b >> > and c are 1d arrays, and d is a 3d array. The statement says: to >> > calculate a at a given index pair i,j (say 0,0) you substitute >> for i,j >> > on the right. And the sum sums over the third index of the 3d >> array d. >> > The notation further says that the bounds for the summation >> depend on >> > what you substitute for i. So to fill the array a like that you >> need to >> > substitute all values in the domian (say both indices run from 0 >> to 99 >> > for a 100x100 array), and for efficiency it would be best if the >> right >> > hand side would result in an iterator that substitutes subsequent >> all >> > values in series. >> >> OK, the syntax for your tensor expressions needs work, but I think >> what >> you're shooting for is certainly doable. How about a syntax like >> this: >> >> a[i][j] = b[i] * ( c[j] - sum( (d[i][j][k], k = (i-1,1)) ) ) >> >> This is a valid C++ expression, and I think there could be enough >> type >> information in it to make it do something useful. Here is a simple >> program that makes the above well-formed, and also defines a very >> rudimentary the grammar for tensor expressions, with transforms that >> calculate the expression's dimensionality. That's important because >> you >> don't want to assign a 2-D array to a 1-D array, for instance. >> >> [...] > > Hey, wow, a full implementation as a response :). Seems very lean > and mean, and I will have to look at it further. What I just tried > was defining two domains very similar to the calculator example, and > then I was going to have syntax with round brackets like this: > > a(i, j) = b(i) * ( c(j) - sum( d(i,j,k), k, i-1, 1) ) ) > so one domain was to be for arrays (a,b,c,d) and one for the indices > (i,j,k). But I could not get the grammar to check for the function > syntax. somehow the proto extends mechanism just passed through all > kinds of function call expressions, even though I explicitly > specified only things like: > > boost::proto::function< array_grammar, index_grammar > > > and still things like a(a) compile. any ideas where I am going wrong? > ok, answering my own question. Turns out the calculator example used a grammar with a match-all-terminals to specify terminals, so it could not distinguish between index placeholders and arrays. got that now and got my first fully grammar checked expression tree printed. now moving towards contractions, dimension checks, and actually getting my array implementation in there and generating iterators to evaluate the expressions. stay tuned for more problems (and again much thanks to eric niebler for the prompt and insightful response!). Daniel

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Compile error OSX Callback problem for FSEventsCallback
by Bill McLean 03 Jan '09

03 Jan '09

I'm trying to code up a FSEvent callback using a member function. I may be suffering from a case of the post holiday stupids :) I am using both the boost::bind and boost::function libraries. I have the following declaration for declaring the signature of the FSEventCallback: typedef boost::function<void ( ConstFSEventStreamRef streamRef, // _1 void *clientCallBackInfo, // _2 size_t numEvents, // _3 void *eventPaths, // _4 const FSEventStreamEventFlags eventFlags[], // _5 const FSEventStreamEventId eventIds[] // _6 )> FSEventCallbackT; The above typedef has been derived from the OSX FSEvent API definition for the FSEventStreamCallback: typedef void ( *FSEventStreamCallback)( ConstFSEventStreamRef streamRef, void *clientCallBackInfo, size_t numEvents, void *eventPaths, const FSEventStreamEventFlags eventFlags[], const FSEventStreamEventId eventIds[] ); The skeleton of the struct that has the member function that is to be the call back is defined as: struct osx::detail { // Callback type definition static const CFAbsoluteTime LATENCY = 2.0; static const unsigned BUF_SIZE = 32768; CFStringRef pathToWatch; CFArrayRef pathsToWatch; FSEventStreamRef streamRef; void *callbackInfo; CFRunLoopRef mainLoop; boost::mutex event_mutex; typedef boost::mutex::scoped_lock lock_type; FSEventCallbackT callBack; // public methods detail( const boost::filesystem::path& base_path ); ~detail() { stop(); } void stop(); void FSEventTriggered( ConstFSEventStreamRef streamRef, // _1 void *clientCallBackInfo, // _2 size_t numEvents, // _3 void *eventPaths, // _4 const FSEventStreamEventFlags eventFlags[], // _5 const FSEventStreamEventId eventIds[] // _6 ); item get_item(); }; In the constructor I get a single compile error in the call to FSEventStreamCreate: osx::detail::detail( const boost::filesystem::path& base_path ) : base_path(base_path), stopped(false), pathToWatch(CFStringCreateWithCString(NULL,base_pa th.string().c_str(), kCFStringEncodingUTF8)), pathsToWatch(CFArrayCreate(NULL, (const void **) &pathToWatch, 1, NULL)) { callBack = boost::bind(&fsmon :: osx::detail::FSEventTriggered, this, _1, _2, _3, _4, _5, _6); streamRef = FSEventStreamCreate(NULL, &callBack, callbackInfo, pathsToWatch, kFSEventStreamEventIdSinceNow, LATENCY, kFSEventStreamCreateFlagNone ); ... } /Users/bill/ardev/CurrentDev/InternalLibs/fsmon/osxExample.cpp:111: error: cannot convert 'FSEventCallbackT*' to 'void (*)(const __FSEventStream*, void*, size_t, void*, const FSEventStreamEventFlags*, const FSEventStreamEventId*)' for argument '2' to '__FSEventStream* FSEventStreamCreate(const __CFAllocator*, void (*)(const __FSEventStream*, void*, size_t, void*, const FSEventStreamEventFlags*, const FSEventStreamEventId*), FSEventStreamContext*, const __CFArray*, FSEventStreamEventId, CFTimeInterval, FSEventStreamCreateFlags)' The typdef for FSEventCallbackT should be the same as the void (*)(const __FSEventStream*, void*, size_t, void*, const FSEventStreamEventFlags*, const FSEventStreamEventId*). I do not see what I am doing incorrectly. Thanks in advance. Bill

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Re: [Boost-users] proto for array expressions
by Daniel Oberhoff 03 Jan '09

03 Jan '09

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[serialization] load/save seem to different header format
by Ewald Peiszer 03 Jan '09

03 Jan '09

Hi I am using the boost s11n lib, version 1.35.0, in combination with a text archive, Windows platform, MSVC++ 2005 compiler. I have split serialize into load and save members, as indicated in the tutorial. However, it seems as if save expects a different header format (ie text stream like stringstream etc) as the corresponding load method outputs. Output of my load method: 22 serialization::archive 4 0 0 10(...) Everything before 10 is s11n housekeeping stuff, 10 is the beginning of the "real" data. Now, if a string like this is used as input for save, then the first variable that is extracted is not the 10 (what it should be) but rather a 0 (or something else which is equally wrong); instead, the 10 shows up as the value of the const unsigned int version which is one of the two parameters of load/save/serialize members. Actually, version is supposed to be 0, I do not set a version number deliberatly anywhere. Playing around, I added a third 0 to the header, resulting in 22 serialization::archive 4 0 0 0 10 and, guess what, this time save(...) correctly managed to de-serialize the data congtained in the string. I tried it also with a single seralize() member (and not splitting into save/load). Save behaviour. The relevant code is below (class code and code to (de)serialize class instance. Has anybody experienced the same or similar problems? Any help is greatly appreciated. If you need more information please ask. Regards Ewald ------------------------------------- Excerpt of class code: class Foo { (...) private: int buflen; // s11n stuff friend class boost::serialization::access; template<class Archive> void save(Archive & ar, const unsigned int version) const { // store length of buffer ar & buflen; // store data itself for (int j = 0; j < buflen; j++) ar & buffer[j]; } template<class Archive> void load(Archive & ar, const unsigned int version) { // get length of buffer ar & buflen; // create buffer with appropriate length deleteBuffer(); init(buflen); // reat data into buffer for (int j = 0; j < buflen; j++) ar & buffer[j]; } BOOST_SERIALIZATION_SPLIT_MEMBER() /* // just to try it with serialize alone: template<class Archive> void serialize(Archive &ar, const unsigned int version) { ar & buflen; } */ (...) }; ------------------------------------- // check the save operation std::stringstream ssq (std::stringstream::in | std::stringstream::out); { const Foo rp(10); boost::archive::text_oarchive oa(ssq); oa << rp; } ----------------------------------- // load { stringstream ss (stringstream::in| std::stringstream::out); ss << s11nbuf << endl; boost::archive::text_iarchive ia(ss); // restore from the archive ia >> rp; } ---------------------------------- (end of post)

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Re: [Boost-users] [Bind] How to bind?
by Max 03 Jan '09

03 Jan '09

Should I use a seperate functor like this? template<class T> struct dereference : public std::unary_function<T*, T> { T operator()(T *pt) { return *pt; } }; A a; boost::bind(&processA, boost::bind(dereference<A>(), _1))(&a); If the answer is yes, is there a safer and stronger equivalence of "dereference" in boost? Thanks again. B/Rgds Max ====================================== Hello On simple question: For struct A {}; void processA(A& a) {} A *pa = new A(); How to write a bind expression that make (pa); equivalent to processA(*pa); I've tried with this: boost::bind(&processA, *_1) but failed. I've also tried with this: processA(*boost::lambda::_1) also failed. Thanks for any information. B/Rgds Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ ) ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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[Bind] How to bind?
by Max 03 Jan '09

03 Jan '09

Hello One simple question: For struct A {}; void processA(A& a) {} A *pa = new A(); How to write a bind expression <BIND> that make <BIND>(pa); equivalent to processA(*pa); I've tried with this: boost::bind(&processA, *_1) but failed. I've also tried with this: processA(*boost::lambda::_1) also failed. Thanks for any information. B/Rgds Max ------------------------------------------------------------------- 新浪空间——与朋友开心分享网络新生活！(http://space.sina.com.cn/ )

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[interprocess] support for private mappings?
by Zeljko Vrba 03 Jan '09

03 Jan '09

Does this library support private, read-write file mappings? Such mapping is copy on write, and modifications to the mapped region remain private to the process that created the mapping. (POSIX: MAP_PRIVATE flag for mmap(), Windows: FILE_MAP_COPY flag to MapViewOfFile and PAGE_WRITECOPY flag to CreateFileMapping)

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Missing regex lib on 1.37
by Larry 03 Jan '09

03 Jan '09

I did a complete build of 1.37 on Windows Vista using VS 2008, VS 2005, and VS .NET 2003 and it appears that none produced debug versions of the libraries. I couldn't see anything that said the debug builds were no longer supported but may have read it and it just didn't register that was what it was saying. I was doing --build_type=complete but even throwing in --variant=debug would not produce the lib. The specific one I was missing was libboost_regex-vc90-mt-gd-1_37.lib. Any suggestions? Pointers? Larry

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