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[regex] How to include named charact class [[:xdigit:]] in user defined character class
by Chandan Nilange 05 Mar '08

05 Mar '08

Hello, I want to include named character class [[:xdigit:]] as a part of another user defined character class. I am not getting the desired results. Pl. find my test example attached. Please let me know how to do this. Regards, Chandan ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

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Re: [Boost-users] Extending Multi Array
by Lang Stefan 05 Mar '08

05 Mar '08

Sorry folks for resending, but I forgot to change the subject line as appropriate when I first replied to the digest. My bad... For the sake of the initial poster (and anyone else interested in this issue) to help him spot my response, below is a copy of that initial reply. I cut away the rest of the digest as well as the original request that I did quote originally, to keep redundancy to a minimum. > Hi Stefan, > > My first guess would be to use initializers, as in > > NetworkMultiArray::NetworkMultiArray(int length) > : boost::multi_array<double,3>( ... ) > { > ... > } > > You shouldn't need to explicitly use the this keyword unless you are > using an obscure compiler and certain syntactically obscure > constructs. > However, if you want to refer to the methods of a superclass that you > have overridden in your own class, use this class's name as a > qualifier, > e. g. if you have a method 'begin()' for your own class that overrides > the 'multi_array::begin()' method, you will need to write > > boost::multi_array<double, 3>::begin(); > > Usually, when you try to extend an existing class it is a good idea to > create a typedef for your superclass, so it's easier to refer to it's > methods. In your case define a typdef like this: > > typedef boost::multi_array<double, 3> super; > > If you do that, you can forward calls to method overrides of your own > class to the baseclass by simply calling super::{_methodname_(...)}. E. > g. the above call would be reduced to > > super::begin(); > > Note that some methods cannot be overriden, such as the copy > constructors or assignment operators, so you will need to provide those > for your own class and explicitely call the base class methods inside: > > NetworkMultiArray& NetworkMultiArray::operator=(const NetworkMultiArray& other) > { > super::operator=(other); // explicit use of operator= neccessary here! > // copy extended stuff here > // ... > return *this; > } > > > Hope this helps! > > Regards, > Stefan (another one)

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[foreach][range] How would BOOST_REVERSE_FOREACH be implemented?
by Pete Bartlett 05 Mar '08

05 Mar '08

Boost.Foreach is such a great piece of kit that once you start using it you just can't stop. Indeed I like working directly with values rather than iterators so much that is feels normal for me to write something like BOOST_FOREACH( value_type x , make_iterator_range( rbegin( seq ) , rend( seq ) ) whenever I wish to reverse iterate over a sequence. My co-workers are not big fans of typing though, so they want a REVERSE_FOREACH. At first naïve glance it looks easy to implement in terms of the original FOREACH: template<typename C> inline iterator_range</* something */> make_reverse_iterator_range(C& c) { return make_iterator_range( rbegin(c) , rend(c) ); } #define REVERSE_FOREACH( x , container ) BOOST_FOREACH( x , make_reverse_iterator_range( container ) ) This works fine when container is an lvalue. But then co-workers, used to the wonders of the original FOREACH, inevitably start to use the new macro with rvalues and get a crash due to dangling references (- the iterator_range's members point to departed quantities.....) and if you could somehow work around that, there is the issue hidden inside the "/* something */" that you have to cope with fact that MSVC has no proper const rvalue detection. Finally the #define MACRO(x,y) ANOTHER_MACRO( f(x) , g(y) ) style is not recommended because they are brittle in the face of x and/or y themselves being macros. ... but all these issues are exactly the ones that BOOST_FOREACH itself solves! Thus surely it is technically possible to write a REVERSE_FOREACH that works with rvalues as well as lvalues, e.g. by essentially copying and pasting the FOREACH implementation and replacing "begin" and "end" by "rbegin" and "rend" in the vital places. However one feels there may be a better way... has anyone had a go at creating a "fully-functional" REVERSE_FOREACH and could offer me any advice? If indeed the task is fairly intricate and requires re-use of foreach internals, would the library author consider including something in the library itself? Many thanks for reading, Pete Bartlett

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Re: [Boost-users] Boost-users Digest, Vol 1561, Issue 2
by Lang Stefan 05 Mar '08

05 Mar '08

Hi Stefan, My first guess would be to use initializers, as in NetworkMultiArray::NetworkMultiArray(int length) : boost::multi_array<double,3>( {enter appropriate constructor parameters here} ) { ... } You shouldn't need to explicitly use the this keyword unless you are using an obscure compiler and certain syntactically obscure constructs. However, if you want to refer to the methods of a superclass that you have overridden in your own class, use this class's name as a qualifier, e. g. if you have a method 'begin()' for your own class that overrides the 'multi_array::begin()' method, you will need to write boost::multi_array<double, 3>::begin(); Usually, when you try to extend an existing class it is a good idea to create a typedef for your superclass, so it's easier to refer to it's methods. In your case define a typdef like this: typedef boost::multi_array<double, 3> super; If you do that, you can forward calls to method overrides of your own class to the baseclass by simply calling super::{_methodname_(...)}. E. g. the above call would be reduced to super::begin(); Note that some methods cannot be overriden, such as the copy constructors or assignment operators, so you will need to provide those for your own class and explicitely call the base class methods inside: NetworkMultiArray& NetworkMultiArray::operator=(const NetworkMultiArray& other) { super::operator=(other); // explicit use of operator= neccessary here! // copy extended stuff here // ... return *this; } Hope this helps! Regards, Stefan (another one) > -----Original Message----- > > Message: 3 > Date: Tue, 4 Mar 2008 16:21:12 +0100 > From: "Klett, Stefan" <stefan.klett(a)iwr.fzk.de> > Subject: [Boost-users] Extending Multi Array > To: <boost-users(a)lists.boost.org> > Message-ID: > <53834FBAA22A7F43B76C1BCD2D5A09D3026B16A0(a)FZKMSX6.ka.fzk.de> > Content-Type: text/plain; charset="us-ascii" > > Hi list members, > > This is a more or less a general kind of " how to extend container > classes" question - > I'm trying to write a class which inherits from > boost::multi_array - the > to get a kind of matrix class with some additional service routines. > Maybe it is a lack of experience - but I for the time being I > don't know > how to solve the problem to access the constructor of > multi_array in my > own class to initialize my matrix class - my current guess was to use > the "this" pointer but it had not worked out like I supposed > it to do. > > class NetworkMultiArray: public boost::multi_array<double,3> > { > public: > NetworkMultiArray(int); > virtual ~NetworkMultiArray(); > }; > > Here is the constructor code: > > > NetworkMultiArray::NetworkMultiArray(int length) > { > this::iterator iter3; > typedef this::template subarray<2>::type::iterator iter2; > typedef this::template subarray<1>::type::iterator iter1; > > for( iter1 i = *this.begin(); iter1 != *this.end(); iter1++){ > for(iter2 ii = (*i).begin(); ii != (*i).end(); ii++){ > for(iter3 iii = (*ii).begin(); iii != > (*ii).end(); iii++){ > *iii = 0.0 ; > } > } > } > } > sure this does not work - and is the result from trying to adapt the > iterator example from the documentation. > > my aim is to handle the NetworkMultiArray like a > boost::multi_array and > initialize it to zero - further it would be nice if somebody > could tell > me how I could assign a length to the array and the subarrays. > The key-point is that I want to use my class > (NetworkMultiArray) like a > multi_array by inheritance of the multi_array features of > boost:multi_array. > > Thank you very much in advance. > Best regards > Stefan

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boost::ptr_array to use or not?
by j.c. 05 Mar '08

05 Mar '08

Hi, I have an pointer array of objects as follows: bucket * m_buckets[BUCKET_SIZE]; Because this array is a set size does it make sense to use a boost::ptr_array? boost::ptr_array<bucket, BUCKET_SIZE> m_buckets; * Note: One thing I first noticed with boost::array is that I cannot perform operations such as inserting at a desired index: // Existing code. m_buckets[bit] = new bucket(k,v); My goal is to use as many smart pointers as I can and less heap allocation. Thanks in advance, jc

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[bind] Template deduction
by Robert Dailey 05 Mar '08

05 Mar '08

Hi, Suppose I have the following code: template< typename T > void DoFoo( int number, T object ) { } void main() { std::list<std::string> myStrings; // Assume myStrings is full of something... std::for_each( myStrings.begin(), myStrings.end(), boost::bind( &DoFoo, 5, _1 ) ); } On MSVC 9, this will not compile because DoFoo is a template, and at some point, boost::bind can't take a template as the function to call, or it can't deduce the function's template arguments. Is there a way I can make this work? Thanks.

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boost posix time
by Aljaz 04 Mar '08

04 Mar '08

Hello I'm developing server and client applications and I need ping-pong mechanism to get ping time betwen them (time needed for data to arrive).. I've been thinking the best way would be to send Code: boost::posix_time::microsec_clock::universal_time()from server to client, which would then just reply with its own universal_time() .. The first problem is I dont know how to store universal_time() as an int/long.. I know I can store it as a string but this would take extra cpu to parse the data each time (with boost posix library).. All the data I send is serialized - maybe I could just serialize the Code: boost::posix_time::ptimeobject and send over? The next thing is what if server's time zone is gmt+1 and client's gmt+3? Will that affect the the time if I do the subtraction to get the ping time? If so, what can I do about it? Maybe anyone has better solution in mind? Thanks a lot for help

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Ann: Floating Point Utilities Review starts today
by John Maddock 04 Mar '08

04 Mar '08

The review of Johan Rade's floating point utilities starts today. Code and docs can be downloaded from : http://www.boost-consulting.com/vault/index.php?action=downloadfile&filenam… The library consists of three parts: 1) Floating point classification routines: these are optimised implementations of the C99 and C++ TR1 functions fpclassify, isinf, isnan, isnormal and isfinite. From Boost-1.35 onwards these are already a part of Boost.Math (see http://svn.boost.org/svn/boost/trunk/libs/math/doc/sf_and_dist/html/math_to…) so if accepted the two implementations will get merged. The review here should focus on the implementation used, and testing on whatever platforms you have available - in particular are there any circumstances (compiler optimisation settings etc) where this implementation breaks? 2) Sign manipulation functions: implementations of the C99 and C++ TR1 functions copysign and signbit, plus the changesign function. Two of these (signbit and copysign) are currently undocumented members of Boost.Math, and again the two implementations will get merged if this library is accepted. Again the main focus of the review here is the implementation, and testing thereof especially in the presence of compiler optimisations. 3) C++ locale facets: these will read and write non-finite numbers in a portable and round-trippable way: that is not otherwise possible with current C++ std library implementations. These are particularly useful for number-serialisation for example. Since the design is already specified by the C++ standard for these facets, your review here should focus on implementation, testing, documentation, and perhaps where in Boost these should best be placed if accepted. These look to be a useful collection of utilities, so I'll look forward to your reviews, Regards, John Maddock, Floating Point Utilities Review Manager.

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Boost::random: Using linear congruential etc.
by Hans Mull 04 Mar '08

04 Mar '08

Hi! A few days ago I started to try out the boost::random library. Now I have a problem: If you don't want to use the "special cases" like minstd_rand[0] for linear_congruential hellekalek1995 for inverse congruential algorithm, how do you use them? I have non-constant parameters (which are not know at compile time). It would be nice if you give me some examples about how to use these "general case" algorithms. Best regards, Hans

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boost::iostreams zlib compression
by j.c. 04 Mar '08

04 Mar '08

Ok I think this sucks. :-) Here is my code to implement zlib compression/decompression via boost. However since is uses streams I cannot simply pass a buffer. This code is intended for compress socket buffers, but is pathetically slow. HAs anyone done this? What can I improve? The copy seems to be the bottle neck. thx jc Here is my code: #include <boost/iostreams/copy.hpp> #include <boost/iostreams/filter/zlib.hpp> #include <boost/iostreams/device/file.hpp> #include <boost/iostreams/stream.hpp> #include <boost/iostreams/filtering_stream.hpp> #include <boost/iostreams/detail/config/zlib.hpp> using namespace boost::iostreams; std::string compress(std::string data) { std::stringstream compressed; std::stringstream decompressed; decompressed << data; boost::iostreams::filtering_streambuf<boost::iostreams::input> out; out.push(boost::iostreams::zlib_compressor()); out.push(decompressed); boost::iostreams::copy(out, compressed); return compressed.str(); } std::string decompress(std::string data) { std::stringstream compressed; std::stringstream decompressed; compressed << data; boost::iostreams::filtering_streambuf<boost::iostreams::input> out; out.push(boost::iostreams::zlib_decompressor()); out.push(compressed); boost::iostreams::copy(out, decompressed); return decompressed.str(); } int main() { std::string data = compress("boo!"); std::cout << data << std::endl; std::cout << decompress(data) << std::endl; return 0; }

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