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physical quantities
by Andy Little 17 Jun '04

17 Jun '04

The next version of my physical quantities libary pqs-1-01-04 is available on my site at: http://www.servocomm.freeserve.co.uk/Cpp/pqs-1-01-04/download.html The original type has now been augmented by another. The original type has now been renamed as a 'ct-quantity' representing a physical quantity whose units cannot be modified at run-time. The other type is the 'rt-quantity', whose units can be modified at run-time. The two types are of course compatible and the rt-quantity in particular is useful for further derivation, for instance into a physical quantity whose units can be set and interrogated via strings ie "mm, kgf" etc of which there is an example in the examples directory. The first question many will ask about such a library is : "How does the run-time speed/memory performance compare with using inbuilt types?." That is an important question, but to me not the most important one. (The answer is that this is implementation dependent and the current implementation is not optimal) Having used the library for some time its power seems to lie in the fact that it models a concept quite accurately from a programmers point of view. IOW what you can do with the type is restricted (by the compiler) to (some subset of) the entity that it models. The reason that this is powerful is difficult to define, but can be summed up in the saying: " a picture is worth a thousand words" I now see more clearly what those who wanted to see currency conversion and number of apples per kumquat or whatever where driving at. However these are not physical-quantities. C++ does have the ability to express those concepts, but they lie outside the remit of the concept that this library models. Nontheless such concepts would be useful. So in a network model a byte, packet etc would be a concept which would be modelled by a C++ type. Strongly enforcing the rules by which entities interact is satisfying , I guess, because it clarifies the mental picture of a program. Modelling everything by a double or an int (should number_of_bytes_received be convertible to double ... probably not etc) means everything is mush. So on a personal note designing the library has been very rewarding. As I spend much time GUI programming, it strikes me that the next useful concepts are those of model-space, view-space, paper-space etc. Here a point in space would be represented by different types which could only exist in the relevent space, but have the intelligence to perform transforms from one space to another. Similarly where one is modelling (say) magnetic flux density at a point x, y, z , the role of the view-space would be to convert form the entity in model-space to 'some representation ' in the view-space or the paper-space. The obvious candidates for the types in model-space being the ct-quantity of course. regards Andy Little

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Using the Boost license
by Geoff Leyland 17 Jun '04

17 Jun '04

Hi, I have a couple of small libraries I'm "releasing" to a few other people (well, anybody really, but so far only a few). Can I use the BSL on my software even though it's not part of boost? Do I have to make any changes? thanks for your time, Geoff

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RE: [boost] Re: static sized strings (non-virtual implementation)
by Reece Dunn 17 Jun '04

17 Jun '04

John Nagle wrote: >That's a much better approach than the previous one. >It's sound C++, and it's simple. >All the operations go in string_base. fixed_string >need only allocate space. I have now checked in a working implementation of the approach I suggested. It uses a trick to pass the information to the implementation via the basic_string_impl class and has a complicated implementation of swap (non-virtual :)!). The only functions not available to [w]char_string are substr and +, but these are available in fixed_string itself. I have also fixed the problems with fsstring.hpp and Borland, since Borland may make strcpy, etc macro functions to its intrinsic versions (__strcpy__, etc.) Regards, Reece _________________________________________________________________ Want to block unwanted pop-ups? Download the free MSN Toolbar now! http://toolbar.msn.co.uk/

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type_traits for checking derived type
by D-Swat 17 Jun '04

17 Jun '04

Hi, some code: template <typename DerivedT> class A { BOOST_STATIC_ASSERT((boost::is_convertible<A<DerivedT>*, B*>::value)); [...] }; class B : public A<B> { }; I want to check if the template parameter really specifies a derived type. But the assert is always false. How can i solve this? bye

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Re: Boost Digest, Vol 756, Issue 1
by Eric Ford 17 Jun '04

17 Jun '04

> The next version of my physical quantities library pqs-1-01-04 is > available on my site at: > > http://www.servocomm.freeserve.co.uk/Cpp/pqs-1-01-04/download.html > ... Andy, Thank you for your work on this very important area of development. From just quickly looking at the examples, it appears that you choose to use different types for quantities that have the same dimensions but different units. I don't think that is a good idea. You can search the archives for the discussions several of us had about similar issues, mostly a few years ago. If you still disagree, I'd like to hear why. Perhaps, you could summarize the main similarities and difference between your library and other similar libraries. For example, there's Walter Brown's SIUnits, as well as a couple of drafts that have been uploaded to the boost vault. I know I posted ebf_units a while back to give people something to work from. And I believe there were one or two others there as well. Thanks, Eric

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applied patch to boost::tuple
by Toon Knapen 17 Jun '04

17 Jun '04

I just applied the patch below to boost/tuple/detail/tuple_basic.hpp to port it to IBM/VisualAge. I tried to contact Jaako Jarvi but the email address listed in the copyright statement is not valid anymore ;-( Index: tuple_basic.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/tuple/detail/tuple_basic.hpp,v retrieving revision 1.23 retrieving revision 1.24 diff -u -r1.23 -r1.24 --- tuple_basic.hpp 28 Oct 2003 09:42:43 -0000 1.23 +++ tuple_basic.hpp 17 Jun 2004 07:01:13 -0000 1.24 @@ -43,6 +43,8 @@ #include "boost/type_traits/cv_traits.hpp" #include "boost/type_traits/function_traits.hpp" +#include "boost/detail/workaround.hpp" // needed for BOOST_WORKAROUND + namespace boost { namespace tuples { @@ -97,12 +99,22 @@ template<class RET, class HT, class TT > inline static RET get(const cons<HT, TT>& t) { +#if BOOST_WORKAROUND(__IBMCPP__,==600) + // vacpp 6.0 is not very consistent regarding the member template keyword + // Here it generates an error when the template keyword is used. + return get_class<N-1>::get<RET>(t.tail); +#else return get_class<N-1>::BOOST_NESTED_TEMPLATE get<RET>(t.tail); +#endif } template<class RET, class HT, class TT > inline static RET get(cons<HT, TT>& t) { +#if BOOST_WORKAROUND(__IBMCPP__,==600) + return get_class<N-1>::get<RET>(t.tail); +#else return get_class<N-1>::BOOST_NESTED_TEMPLATE get<RET>(t.tail); +#endif } }; @@ -194,11 +206,17 @@ typename element<N, cons<HT, TT> >::type >::non_const_type get(cons<HT, TT>& c BOOST_APPEND_EXPLICIT_TEMPLATE_NON_TYPE(int, N)) { - return detail::get_class<N>::BOOST_NESTED_TEMPLATE +#if BOOST_WORKAROUND(__IBMCPP__,==600 ) + return get_class<N>:: +#else + return get_class<N>::BOOST_NESTED_TEMPLATE +#endif get< typename access_traits< typename element<N, cons<HT, TT> >::type - >::non_const_type>(c); + >::non_const_type, + HT,TT + >(c); } // get function for const cons-lists, returns a const reference to @@ -209,11 +227,17 @@ typename element<N, cons<HT, TT> >::type >::const_type get(const cons<HT, TT>& c BOOST_APPEND_EXPLICIT_TEMPLATE_NON_TYPE(int, N)) { +#if BOOST_WORKAROUND(__IBMCPP__,==600) + return detail::get_class<N>:: +#else return detail::get_class<N>::BOOST_NESTED_TEMPLATE +#endif get< typename access_traits< typename element<N, cons<HT, TT> >::type - >::const_type>(c); + >::const_type, + HT,TT + >(c); } // -- the cons template --------------------------------------------------

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RE: [boost] Boost.Test
by Roman Yakovenko 17 Jun '04

17 Jun '04

Jagmohan wrote: > Is it possible to just carve out Boost.test package > separately from entire > Boost? Yes, bcp utility is your friend. >From bcp documentation: "The bcp utility is a tool for extracting subsets of Boost, it's useful for Boost authors who want to distribute their library separately from Boost, and for Boost users who want to distribute a subset of Boost with their application." Roman --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com) Version: 6.0.707 / Virus Database: 463 - Release Date: 6/15/2004

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RE: [boost] Re: static sized strings (struct hack)
by Reece Dunn 17 Jun '04

17 Jun '04

John Nagle wrote: > I think we're back to using an abstract base class. >The hacks to get around it introduce worse problems. I would agree. I have been trying to find a way around the problem and have (sortof) by having a base class: template< typename CharT > class string_base { private: size_t len, cap; // length & capacity CharT * buf; // data buffer public: string_base( CharT * b, size_t c, size_t l ): len( l ), cap( c ), buf( b ){} // non-virtual implementation }; template< size_t n, typename CharT > class fixed_string: public string_base { private: CharT data[ n + 1 ]; public: fixed_string(): string_base( data, n + 1 ){} }; The problems with this revolve around swapping/construction/copying and interfacing with (in my case) basic_string_impl. I cannot find a way around these problems without sacrificing something. > Take a look at my approach at >http://www.animats.com/source/index.html > >That's a straightforward approach. The only >fundamental objection is that you take a virtual function >call overhead on some operations. That's the same with both approaches. Both designs are fundamentally the same and I don't see a way around this. It would be interesting to do a comparison with the 3 approaches (raw strcpy, etc on a char[ n ] buffer; your approach and mine) in virtual and non-virtual situations to compare performance. >What needs to be done to that? Are you aiming at supporting basic_string operations? If so, the class needs more work (all the find functions, for instance). If, however, you are just going for C-string replacement it is fine. One point on naming: the wide-character operations are wcscpy (strcpy), wcscat (strcat), wcscmp (strcmp), wcslen (strlen) and [v]swprintf (sprintf). >Should I check it into the Boost sandbox, and >if so, how? Comments, please. Thanks. Go for it! You need a sourceforge account with CVS write access to the boost-sandbox. There is documentation at the sourceforge site for setting it up and pointers to the various tools. You will need to contact an administrator for write access once you have the sourceforge stuff setup. Regards, Reece _________________________________________________________________ Express yourself with cool new emoticons http://www.msn.co.uk/specials/myemo

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Two bugs generating docs using bjam --v2
by Angus Leeming 16 Jun '04

16 Jun '04

I have been following Douglas Gregor's prescriptions on how to generate boostbook docs, outlined on the boost web pages. All works beautifully, so many thanks. However, I find that generating reference docs using bjam and doxygen results in a couple of errors in the docs. I don't know whether the problem lies in bjam or in doxygen, but thought you should have a heads up. This is all with boost-jam-3.1.9-1 doxygen-1.3.4-1 Example 1 A header file containing: template <typename DataT> class process_base { protected: process_base(); process_base(process_base const &); }; results in docs: template<typename DataT> class process_base { public: // construct/copy/destruct process_base(); process_base(process_base const }; Note the change from 'protected' to 'public'. Example 2. This class: struct pprocess_data { /// Type used for file descriptors. typedef int fd_t; /// Pipe used to write to child process' stdin. fd_t wpipe; /// Two pipes to read from child process' stdout and stderr. fd_t rpipe[2]; }; results in these docs: struct pprocess_data { // types typedef int fd_t; // Type used for file descriptors. // public member functions fd_t wpipe; fd_t rpipe; }; Note that the 'rpipe' is no longer an array. Also, shouldn't the 'public member functions' comment be supressed? bjam warning messages are: Cannot handle sectiondef with kind=private-type Cannot handle sectiondef with kind=private-attrib Cannot handle sectiondef with kind=related Cannot handle sectiondef with kind=protected-type Cannot handle sectiondef with kind=protected-attrib I can supply header files and jamfile if required. Regards, Angus

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[bind] Patch that enables pass-by-value
by Lars Rune Nøstdal 16 Jun '04

16 Jun '04

Hi, I'm a new user of this library, so not sure if this is a good idea or the best way to do this. void f(int x) { cout << "f(int): " << x << endl; } int x = 0; bind(f, _1)(x); //bind(f, _1)(1); // Does not work. bind(f, _1)(val<int>(1)); // But this does after patching. This enables the user to pass-by-value if he specifies it explicitly, here is the patch: Index: boost/bind.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/bind.hpp,v retrieving revision 1.36 diff -u -c -d -r1.36 bind.hpp *** boost/bind.hpp 8 Jun 2004 13:43:03 -0000 1.36 --- boost/bind.hpp 15 Jun 2004 19:13:43 -0000 *************** *** 27,32 **** --- 27,33 ---- #include <boost/type.hpp> #include <boost/bind/arg.hpp> #include <boost/detail/workaround.hpp> + #include <boost/val.hpp> // Borland-specific bug, visit_each() silently fails to produce code Index: boost/bind/bind_template.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/bind/bind_template.hpp,v retrieving revision 1.4 diff -u -c -d -r1.4 bind_template.hpp *** boost/bind/bind_template.hpp 7 Mar 2004 16:39:15 -0000 1.4 --- boost/bind/bind_template.hpp 15 Jun 2004 19:13:43 -0000 *************** *** 27,32 **** --- 27,38 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1> result_type operator()(val<A1> a1) + { + list1<A1> a(a1); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1> result_type operator()(A1 & a1) { list1<A1 &> a(a1); *************** *** 39,44 **** --- 45,56 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2> result_type operator()(val<A1> a1, val<A2> a2) + { + list2<A1, A2> a(a1, a2); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2> result_type operator()(A1 & a1, A2 & a2) { list2<A1 &, A2 &> a(a1, a2); *************** *** 51,56 **** --- 63,74 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3) + { + list3<A1, A2, A3> a(a1, a2, a3); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3> result_type operator()(A1 & a1, A2 & a2, A3 & a3) { list3<A1 &, A2 &, A3 &> a(a1, a2, a3); *************** *** 63,68 **** --- 81,92 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4) + { + list4<A1, A2, A3, A4> a(a1, a2, a3, a4); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4) { list4<A1 &, A2 &, A3 &, A4 &> a(a1, a2, a3, a4); *************** *** 75,80 **** --- 99,110 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4, class A5> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4, val<A5> a5) + { + list5<A1, A2, A3, A4, A5> a(a1, a2, a3, a4, a5); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4, class A5> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4, A5 & a5) { list5<A1 &, A2 &, A3 &, A4 &, A5 &> a(a1, a2, a3, a4, a5); *************** *** 87,92 **** --- 117,128 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4, class A5, class A6> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4, val<A5> a5, val<A6> a6) + { + list6<A1, A2, A3, A4, A5, A6> a(a1, a2, a3, a4, a5, a6); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4, class A5, class A6> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4, A5 & a5, A6 & a6) { list6<A1 &, A2 &, A3 &, A4 &, A5 &, A6 &> a(a1, a2, a3, a4, a5, a6); *************** *** 99,104 **** --- 135,146 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4, val<A5> a5, val<A6> a6, val<A7> a7) + { + list7<A1, A2, A3, A4, A5, A6, A7> a(a1, a2, a3, a4, a5, a6, a7); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4, A5 & a5, A6 & a6, A7 & a7) { list7<A1 &, A2 &, A3 &, A4 &, A5 &, A6 &, A7 &> a(a1, a2, a3, a4, a5, a6, a7); *************** *** 111,116 **** --- 153,164 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7, class A8> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4, val<A5> a5, val<A6> a6, val<A7> a7, val<A8> a8) + { + list8<A1, A2, A3, A4, A5, A6, A7, A8> a(a1, a2, a3, a4, a5, a6, a7, a8); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7, class A8> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4, A5 & a5, A6 & a6, A7 & a7, A8 & a8) { list8<A1 &, A2 &, A3 &, A4 &, A5 &, A6 &, A7 &, A8 &> a(a1, a2, a3, a4, a5, a6, a7, a8); *************** *** 123,128 **** --- 171,182 ---- BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7, class A8, class A9> result_type operator()(val<A1> a1, val<A2> a2, val<A3> a3, val<A4> a4, val<A5> a5, val<A6> a6, val<A7> a7, val<A8> a8, val<A9> a9) + { + list9<A1, A2, A3, A4, A5, A6, A7, A8, A9> a(a1, a2, a3, a4, a5, a6, a7, a8, a9); + BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0); + } + template<class A1, class A2, class A3, class A4, class A5, class A6, class A7, class A8, class A9> result_type operator()(A1 & a1, A2 & a2, A3 & a3, A4 & a4, A5 & a5, A6 & a6, A7 & a7, A8 & a8, A9 & a9) { list9<A1 &, A2 &, A3 &, A4 &, A5 &, A6 &, A7 &, A8 &, A9 &> a(a1, a2, a3, a4, a5, a6, a7, a8, a9); *** /dev/null Thu Jan 1 01:00:00 1970 --- boost/val.hpp Tue Jun 15 22:00:29 2004 *************** *** 0 **** --- 1,35 ---- + #ifndef BOOST_VAL_HPP_INCLUDED + #define BOOST_VAL_HPP_INCLUDED + + // val.hpp - Usefull helper functions + // + // Copyright (C) 2004 Lars Rune Nøstdal (larsnostdal(a)organizer.net) + // + /* + Distributed under the Boost Software License, Version 1.0. + (See accompanying file LICENSE_1_0.txt or copy at + http://www.boost.org/LICENSE_1_0.txt) + */ + + + namespace boost { + + template<typename T> + struct val { + val(T t) + :value(t) + { + } + + operator T&() + { + return(value); + } + + private: + T value; + }; // val + + } // namespace boost + + #endif // #ifndef BOOST_VAL_HPP_INCLUDED Thanks, Lars Rune Nøstdal

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