February 2009 - Boost-users

proto: analytical-only math functions
by Hicham Mouline 06 Mar '09

06 Mar '09

Hello, There are a few posts these days about generic libraries for math derivation of math functions, analytically or numerically. My objective is to start simple with analytical functions, and to expand the result gradually. I have used proto to define terminals : 1. 1D constants 2. 1D variables 3. 1D basic functions <double (double)> ( c++03 cmath + boost::math ) 4. user-defined functions ( 0 or more dimensions ) HEADER struct constant_tag {}; typedef proto::terminal< constant_tag >::type constant; struct variable_tag {}; typedef proto::terminal< variable_tag >::type variable; template < double (*basic_function_ptr)(double) > struct basic_function_tag { typedef double result_type; result_type operator()(double d) const { return basic_function_ptr(d); } }; proto::terminal< basic_function_tag<std::log> >::type const log = {{}}; // 1 example, I have one of these for each function template <size_t dim =1> struct function_tag {}; template <size_t dim> struct function : proto::terminal< function_tag<1> >::type {}; USER CODE ------------------ constant c; variable x,y,z,t,u,v; function<0> h; function<1> f; function<5> g; My grammar will be very simple for a start. All I want to allow are statements like: 1.variable = constant(proto terminal) or literal (actual number, does it have to be proto terminal), for e.g. x = 5; 2. function definition with the = operator. The LHS of the operator can one of: h = h() = f(x) = g(x,y,z,t,u) = // All arguments of f should be "variable"s only and they can't be repeated, and they have to match the dimension my LHS grammar looks like: template <size_t dim> struct function_def_lhs_grammar : proto::function< function_tag<dim>, proto::vararg< proto::terminal< variable_tag > > > {}; template <> struct function_def_lhs_grammar<0> : proto::or_< proto::terminal< function_tag<0> >, proto::function< function_tag<0>, proto::vararg< proto::terminal< variable_tag > > > {}; But vararg is not what I want at all: I want to have 0 variables (nothing) for the 0-dim function in the proto::function case, And I want to have exactly dim variables in the dim>0 proto::function case. Is it possible to "math-define" the function at the same time of the function<> object definition (in c++ terms) and have the dimension deducted, like: function f(x,y,z) = x+y+z ; The next step will be to worry about the RHS which is the much more complicated bit, regards,

4 18

[regex] Context-sensitive replacement of text using regex_replace
by KEN RODE 03 Mar '09

03 Mar '09

I've been struggling with a problem with using regex_replace this afternoon, and I would appreciate some pointers on properly using the regex package. I've got a file that is similar to a CSS style sheet (it's actually a Qt style sheet) that contains color entries that similar to: rgb( 200, 255, 200 ). I've already successfully written some code that finds these patterns and replaced them with statically determined text, just to verify that I was able to locate them all properly. I have an application in which the color scheme of the user interface (specified in the style sheet) has to change between a daytime and nighttime color scheme. The nighttime color scheme is derived from the daytime color scheme by reducing the luminance of the colors. I'd like to generate the nighttime color scheme from the daytime scheme by extracting the components of the color and applying a calculation to them, then replacing the original text with the new text. The examples on the Boost site for regex_replace all demonstrate replacement with static text. I suspect that I have to do some sort of combination using regex_replace, regex_iterator, and match_results, but I can't quite wrap my head around the documentation for these classes to see how they interoperate. I would appreciate some pointers as to how to proceed.

4 5

Timing of BoostPro 1.38 Installer?
by Scott Meyers 03 Mar '09

03 Mar '09

Does anybody happen to know when an installer will be available for Boost 1.38? Thanks, Scott

5 5

[result_of] member function
by er 03 Mar '09

03 Mar '09

Hi All, Is this feasible? How? class Foo { template<typename Signature> struct result{}; template<typename F> struct result<(F::*f)(value_type)>{ typedef value0_type if f == foo, value1_type if f == bar type; }; value0_type foo(value_type); value1_type bar(value_type); }; How do I invoke result_of to get the result type of F::foo(value_type)?

2 4

Formal Review: Boost.RangeEx
by Thorsten Ottosen 02 Mar '09

02 Mar '09

Dear Developers and Users, It's my pleasure to announce that the review of Neil Groves' RangeEx library starts today and lasts until March 3, 2009. What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

2 1

[Review] Reminder: Boost.RangeEx review is going on
by Thorsten Ottosen 02 Mar '09

02 Mar '09

Dear Developers and Users, The review of Neil Groves' RangeEx library lasts until March 3, 2009. Please find the time to do a review if you are interested in this library. The discussion so far may be found here: http://archives.free.net.ph/message/20090220.122836.73bdbd04.en.html Below you will find a description of the library and information on how to write a review. best regards Thorsten, review manager What is it? +++++++++++ The library provide two very useful extensions to the range library 1. Range-based algorithms. E.g. boost::sort( rng ); which is a convenient wrapper of instead of std::sort( boost::begin(rng), boost::end(rng) ); But the new interface also allows for more expressive code because (on the fly) composition of algorithms suddenly is possible. 2. Range adaptors. E.g. std::vector<int> vec = ...; boost::copy( vec | boost::adaptors::reversed, std::ostream_iterator<int>( std::cout ) ); where the expression "vec | boost::adaptors::reversed" wraps the iterators of the range on the left in reverse iterators. The library provides a wide range (no pun intended) of Range adaptors, and they are a powerful way to create ranges on the fly and pass them to algorithms. Getting the library +++++++++++++++++++ The library may be downloaded from http://www.cs.aau.dk/~nesotto/boost/range_ex.zip or from the Boost vault under "Algorithms". The docs may be browsed online here http://www.cs.aau.dk/~nesotto/boost/libs/range/ Please note that the documentation is integrated with the current Range ilbrary. Therefore the relevant sections for the review is http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/adaptors.html and http://www.cs.aau.dk/~nesotto/boost/libs/range/doc/algorithms.html The code may be browsed here: http://www.cs.aau.dk/~nesotto/boost/boost/range/ Notice the library is header only (exception: the adaptor tokenized() depends on Boost.Regex). Writing a review ++++++++++++++++ If you feel this is an interesting library, then please submit your review to the developer list (preferably), or to the review manager. Here are some questions you might want to answer in your review: - What is your evaluation of the design? - What is your evaluation of the implementation? - What is your evaluation of the documentation? - What is your evaluation of the potential usefulness of the library? - Did you try to use the library? With what compiler? Did you have any problems? - How much effort did you put into your evaluation? A glance? A quick - reading? In-depth study? - Are you knowledgeable about the problem domain? And finally, every review should answer this question: - Do you think the library should be accepted as a Boost library? Be sure to say this explicitly so that your other comments don't obscure your overall opinion. Special considerations ++++++++++++++++++++++ Various RangeEx like libraries have been implemented in the past. You might want to compare with those libraries when you form your oppinion: 1. John Torjo's range lib http://rangelib.synesis.com.au/libs/boost-rangelib-20040913.zip http://torjo.com/rangelib/index.html 2. Adobe's ASL libraries include range-based algorithms: http://stlab.adobe.com/group__algorithm.html I'm looking forward to your review. best regards Thorsten, Review Manager

8 9

[accumulators] Any was to reset an accumulator_set object?
by dhruva 02 Mar '09

02 Mar '09

Hello, I am using boost::accumulator_set to compute mean. After every 100 samples, I need to start afresh. Since I am using accumulator_set as a member variable in a class (I get samples one at a time and need to preserve accumulator_set object across function calls), I need some mechanism to reset it to its initial state. I am not doing anything fancy like using droppable functionality. As a real crude work around, I am keeping 2 objects. The first is not used for any computing and hence its state is same throughout. The computing is done using the second object. After 100 samples, I just copy the first onto the second hoping the state of second object will be same as first which is the initial state. Is there a better way to achieve the above requirement? -dhruva Download prohibited? No problem. CHAT from any browser, without download. Go to http://in.webmessenger.yahoo.com/

3 2

[Interprocess] Trying to include unistd.h on Windows?
by Derek Kivi 02 Mar '09

02 Mar '09

We are using the Interprocess library to make use of shared memory within our code. We are experiencing the following problem when building on Windows. Some of our projects are trying to include unistd.h from workaround.hpp. It looks like this happens if BOOST_WINDOWS is not defined. Tracing back through the header files I pieced together that BOOST_WINDOWS is not defined if BOOST_DISABLE_WIN32 is defined (win32.hpp). And BOOST_DISABLE_WIN32 gets defined if _MSC_EXTENSIONS is not defined (visualc.hpp). >From the MSDN documentation, _MSC_EXTENSIONS is not defined if the Visual C++ Language Extensions are turned off, which in fact they are for these projects. Has anyone else seen this and is there a workaround for getting Boost Interprocess to work on Windows in cases where the Visual C++ Language Extensions are turned off? Thanks, Derek -- Derek Kivi Senior Software Developer QuIC Financial Technologies Inc. Office: +1 403 210 8282 Mobile: +1 403 863 5204 derek.kivi(a)quic.com Risk. Managed. www.quic.com Confidentiality Notice: The information transmitted is intended only for the person(s) or entity(ies) to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited. If you received this email in error, please contact the sender and delete the email and any related material from any computer. ver. QuIC 0707

2 4

serial programs
by Steven Woody 02 Mar '09

02 Mar '09

Hi, I want to write a portable program which need to read/write serial ports. How can boost help this? Thank you. ( I got know basic serial programming in Linux but I have no idea how that it done in Windows ) -- woody then sun rose thinly from the sea and the old man could see the other boats, low on the water and well in toward the shore, spread out across the current.

7 9

Pool ordered_malloc and O(n)
by Georg Sauthoff 02 Mar '09

02 Mar '09

Hi, the boost pool documentation states ordererd_malloc(n) and boost::free(chunk, n) both take O(n). I tested it with a workload of a lot of n=1 and n=2 small allocations. Basically if I just use boost::malloc(2*base_size) even if i just need boost::malloc(base_size) the runtime is 1 min. With ordered_malloc(_)/boost::free(_,_) the runtime explodes (>> 30 minutes) (I terminated the program). Profiling it, one can see, that ordered_malloc dominates the runtime (83 % after a few minutes). Is this a known issue? Is the runtime of ordered_malloc in O(n), i.e. in O(c\cdot n), but the constant factor c is very huge? Best regards Georg Sauthoff

2 2