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Question about boost.extension
by Noah Roberts 28 Jul '08

28 Jul '08

Does this library address the problems associated with calling conventions when using different compilers? Can I compile an application with one compiler and allow users to provide plugins compiled with another? I have my doubts that this is even possible to solve, but I ask anyway.

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[filesystem] two-minute tutorial uses deprecated functions
by Michael Marcin 28 Jul '08

28 Jul '08

The two-minute tutorial section of the filesystem documentation calls leaf() from a dereferenced directory_iterator. The reference documentation shows that dereferencing a directory_iterator yields a directory_entry but the reference documentation for directory_entry shows no leaf member. Eventually I had to track it down in the source code and found out that leaf does exist but is deprecated and not documented. It is probably bad to have the introduction to a library use undocumented functions. Thanks, Michael Marcin

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data_binding library for boost... Any interest?
by Brian Davis 27 Jul '08

27 Jul '08

I looked through boost and if there is a library or facility for data binding in boost I could not find it... So I created and am submitting a simple example for review. Please take a look and give some feedback. I understand that there is quiet a process of review before a library is included in boost. If there is interest or if there is already on going work on the concept than I am interested in helping. Here goes: Data binding should allow for 1 value of primitive type to be changed in code and have 1 to N values be modified based on the event and optional conversion functions. i.e. fanout should be allowed Data binding should allow for cascading changes. Where a->b->c->d where -> represents a binding link when 'a' changes 'c', 'b', and 'd' should change. Data binding should be recursion save where a->b->c->a where a change in 'a' causes a change in 'c', but will not cause a recursive change in 'a' creating a recursive loop. Data binding would be useful in the dataflow library and for work being done on cppgui or for that fact any UI development. This is my first submittal to this list so please bear with me. I have taken the liberty to add the boost license to this code... so it is boost's if the project so chooses to incorporate or enhance the concept. I am not the originator of data binding concept and make no claim to this. I am only providing a simple example for discussion and hopefull inclusion of data binding concept in boost and ....ultimately modify the C++ compiler to provide for a lighter weight solution (events based on modifications of integral types) - Ouch ... yes I know what I am asking here... see the last part of the example output for why I ask this. // Start snip bind_value.hpp ======================================= // // (C) Copyright Brian Davis. // // 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) // // Revision history: // 19 July 2008 // Created - to support and assist in dataflow and dataflow concepts // // This is not currently part of boost! The only reason for the above copyright is to // keep these concepts part of the boost development. boost::data_binding is not // officially part of boost. The goal of this demo code is to elaborate on data binding // and give a simple implementation and an example on how the concept can be applied within C++. #ifndef BOOST_DATA_BINDING_HPP #include <boost/cast.hpp> #include <boost/function.hpp> #include <boost/bind.hpp> #include <boost/foreach.hpp> #include <vector> namespace boost { namespace data_binding { template < class T1, class T2> class bind_values; template <class T> class value { friend class bind_values< class T1, class T2>; public: typedef boost::function< T& (T&) > set_value_function; std::vector<set_value_function> set_value_functions; T& mv_value; // To prevent infinite recursion on a group of three linked variables a->b->c->a. bool mv_entered; protected: private: public: value( T& invalue ) : mv_value( invalue ){ mv_entered = false; }; // Sets require action event handling to update value of binded type.. gets are transparent value& operator=( T& rhs ) { if( set_value_functions.size() && !mv_entered ) { mv_entered = true; BOOST_FOREACH( set_value_function set_value, set_value_functions ) { mv_value = set_value( rhs ); } } else { // Otherwise simple type cast convert mv_value = boost::numeric_cast<T>( rhs ); } mv_entered = false; return *this; } value& operator=( T rhs ) { if( set_value_functions.size() && !mv_entered ) { mv_entered = true; BOOST_FOREACH( set_value_function set_value, set_value_functions ) { mv_value = set_value( rhs ); } } else { // Otherwise simple type cast convert mv_value = boost::numeric_cast<T>( rhs ); } mv_entered = false; return *this; } void add_set_function( set_value_function set_function ) { set_value_functions.push_back( set_function ); } T& operator&( value<T>& value ) { return value.mv_value; } protected: private: }; template < class T1, class T2> class bind_values { friend class value<T1>; friend class value<T2>; public: typedef T1 type1; typedef T2 type2; typedef boost::function< T1& (T1, T2)> convert_to_function; typedef boost::function< T2& (T2, T1)> convert_from_function; convert_to_function convert_to; convert_from_function convert_from; protected: value<T1>& mv_value1; value<T2>& mv_value2; private: public: bind_values ( value<T1>& value1, value<T2>& value2, convert_to_function convertTo, convert_from_function convertFrom ) : convert_to(convertTo), convert_from(convertFrom), mv_value1( value1 ), mv_value2( value2 ) { // Hook up set for value 1 mv_value1.add_set_function( boost::bind( &bind_values::set_value1, this, _1 ) ); // Hook up set for value 2 mv_value2.add_set_function( boost::bind( &bind_values::set_value2, this, _1 ) ); } bind_values( value<T1>& value1, value<T2>& value2 ) : mv_value1( value1 ), mv_value2( value2 ) { // Hook up set for value 1 mv_value1.set_value = boost::bind( &bind_values::set_value1, _1 ); // Hook up set for value 2 mv_value2.set_value = boost::bind( &bind_values::set_value2, _1 ); } protected: T1& set_value1( T1& value ) { if( convert_from ) { // Convert and set value 2 mv_value2 = boost::numeric_cast<T2>( convert_from( mv_value2.mv_value, value ) ); } else { // Otherwise simple type cast convert mv_value2 = boost::numeric_cast<T2>( value ); } // return the value unmodified to the original container return value; } T2& set_value2( T2& value ) { if( convert_to ) { // Convert and set value 1 mv_value1 = boost::numeric_cast<T1>( convert_to( mv_value1.mv_value, value ) ); } else { // Otherwise simple type cast convert mv_value1 = boost::numeric_cast<T1>( value ); } // return the value unmodified to the original container return value; } private: }; } } // namespace boost::data_binding template <class T> std::ostream& operator<<( std::ostream& os, boost::data_binding::value<T>& rhs ) { os << rhs.mv_value;; return os; } #endif // end snip bind_value.hpp ======================================= // Start snip bind_value_test.hpp ======================================= // // (C) Copyright Brian Davis. // // 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) // // Revision history: // 19 July 2008 // Created - to support and assist in dataflow and dataflow concepts // // This is not currently part of boost! The only reason for the above copyright is to // keep these concepts part of the boost development. boost::data_binding is not // officially part of boost. The goal of this demo code is to elaborate on data binding // and give a simple implementation and an example on how the concept can be applied within C++. #include <iostream> #include <boost/cstdint.hpp> #include <boost/bind.hpp> #include <boost/data_binding/bind_value.hpp> #define MAX_CELSIUS 100 #define MIN_CELSIUS -17.8 #define MAX_RAW_SENSOR_COUNTS 4095 // use of a class is not necessary it is only shown to prove it is possible. It may // make more sense just to have conversion functions class AClass_That_Is_A_Converter { public: protected: boost::data_binding::value<boost::uint32_t> rawCelsiusCountsFromSensor; boost::data_binding::value<float> calibratedCelsiusDataFromSensor; boost::data_binding::value<float> calibratedFahrenheit; boost::uint32_t rawSensorValue; float fahrenheit; float celsius; boost::data_binding::bind_values<float, boost::uint32_t> mv_celsiusToSensorBinder; boost::data_binding::bind_values<float, float> mv_celsiusToFahrenheitBinder; private: public: AClass_That_Is_A_Converter( void ) : rawCelsiusCountsFromSensor(rawSensorValue), calibratedCelsiusDataFromSensor(celsius), calibratedFahrenheit(fahrenheit), mv_celsiusToSensorBinder ( calibratedCelsiusDataFromSensor, rawCelsiusCountsFromSensor, boost::bind( &AClass_That_Is_A_Converter::convertCelsiusRawToCalibrated, this, _1, _2 ), boost::bind( &AClass_That_Is_A_Converter::convertCelsiusCalibratedToRaw, this, _1, _2 ) ), mv_celsiusToFahrenheitBinder ( calibratedCelsiusDataFromSensor, calibratedFahrenheit, boost::bind( &AClass_That_Is_A_Converter::convertFahrenheitToCelsius, this, _1, _2 ), boost::bind( &AClass_That_Is_A_Converter::convertCelsiusToFahrenheit, this, _1, _2 ) ) {} virtual ~AClass_That_Is_A_Converter( void ){} void test( void ) { std::cout << "Starting test of data binding" << std::endl; try { std::cout<< "Note raw temp represents the raw value of an Analog to Digital Converter" << std::endl; std::cout<< "The range is from 0-4095 which represents -17.8 - 100 degrees on the Celsius" << std::endl; std::cout<< "scale and 0 - 212 degrees on the Fahrenheit" << std::endl; std::cout<< "Setting calibratedFahrenheit to 70.0 degrees fahrenheit" << std::endl; std::cout<< "calibratedFahrenheit = 70.0f;" << std::endl; calibratedFahrenheit = 70.0f; std::cout << "What does the celsius value contain? ... should be ~21.1" << std::endl; showValues(); std::cout << "Now change the raw sensor value and see what happens to Celsius and Fahrenheit" << std::endl; std::cout<< "rawCelsiusCountsFromSensor = 4095;" << std::endl; rawCelsiusCountsFromSensor = 4095; std::cout << "Celsius should equal ~100" << std::endl; std::cout << "Fahrenheit should equal ~212" << std::endl; showValues(); std::cout << "Now change celsius see what happens to raw and farenheit" << std::endl; std::cout<< "calibratedCelsiusDataFromSensor = 32.2;" << std::endl; calibratedCelsiusDataFromSensor = 32.2; std::cout << "Fahrenheit should equal ~90 degress" << std::endl; showValues(); std::cout << "Note changing original values will not have any affect in C++ " << std::endl; std::cout << "this makes me sad :-( as a class wrapper and operator overloading" << std::endl; std::cout << "is necessary... without changing the compiler... hint.... hint..." << std::endl; std::cout << "fahrenheit = 10;" << std::endl; fahrenheit = 10; showValues(); std::cout << "No change in values :-( !!!" << std::endl; // Note one to many fanout is possible and the example shows 1 to 2 fanout with Celsius // fanning out to Raw and Fahrenheit values. A more advanced implementation is also possible // which includes the use of the lamda library and place holders. This is just a simple // example which I hope will "prime the pump" for work on a data_binding library with in // the Boost development. Most direct use for this library is within data_flow library. // Another use is within the cppgui library which would allow modification of data to directly // affect values of UI controls and display values. } catch( std::exception& ex ) { std::cout << "Failed with exception: " << ex.what(); } std::cout << "End of data binding test" << std::endl; } void showValues( void ) { std::cout << std::endl; std::cout << "Fahrenheit : " << calibratedFahrenheit << std::endl; std::cout << "Celsius : " << calibratedCelsiusDataFromSensor << std::endl; std::cout << "Raw Temp To/From Sensor A/D converter : " << rawCelsiusCountsFromSensor << std::endl; std::cout << std::endl; std::cout << "fahrenheit : " << fahrenheit << std::endl; std::cout << "celsius : " << celsius << std::endl; std::cout << "rawSensorValue : " << rawSensorValue << std::endl; std::cout << std::endl; std::cout << "====================================================================" << std::endl; } protected: float& convertFahrenheitToCelsius ( float& celsius , float& fahrenheit ) { return celsius = ((fahrenheit - 32.0) * 5.0) / 9.0; } float& convertCelsiusToFahrenheit ( float& fahrenheit, float& celsius ) { return fahrenheit = celsius * (9.0 / 5.0) + 32.0; } float& convertCelsiusRawToCalibrated ( float& calibratedValue, boost::uint32_t& rawValue ) { return calibratedValue = ( MAX_CELSIUS - MIN_CELSIUS ) * (rawValue / MAX_RAW_SENSOR_COUNTS) + MIN_CELSIUS; } boost::uint32_t& convertCelsiusCalibratedToRaw ( boost::uint32_t& rawValue, float& calibratedValue ) { // Raw is from 0 to 4095 ( a 12 bit number of an // Analog to Digital converter // map zero (fahrenheit) to water boiling to raw value of 4095 return rawValue = MAX_RAW_SENSOR_COUNTS * ( calibratedValue - MIN_CELSIUS) / ( MAX_CELSIUS - MIN_CELSIUS ); } private: }; int main(int argc, char **argv) { AClass_That_Is_A_Converter anExampleOfDataBinding; anExampleOfDataBinding.test(); } // end snip bind_value_test.hpp ======================================= // Start snip program output ======================================= Starting test of data binding Note raw temp represents the raw value of an Analog to Digital Converter The range is from 0-4095 which represents -17.8 - 100 degrees on the Celsius scale and 0 - 212 degrees on the Fahrenheit Setting calibratedFahrenheit to 70.0 degrees fahrenheit calibratedFahrenheit = 70.0f; What does the celsius value contain? ... should be ~21.1 Fahrenheit : 70 Celsius : 21.1111 Raw Temp To/From Sensor A/D converter : 1352 fahrenheit : 70 celsius : 21.1111 rawSensorValue : 1352 ==================================================================== Now change the raw sensor value and see what happens to Celsius and Fahrenheit rawCelsiusCountsFromSensor = 4095; Celsius should equal ~100 Fahrenheit should equal ~212 Fahrenheit : 212 Celsius : 100 Raw Temp To/From Sensor A/D converter : 4095 fahrenheit : 212 celsius : 100 rawSensorValue : 4095 ==================================================================== Now change celsius see what happens to raw and farenheit calibratedCelsiusDataFromSensor = 32.2; Fahrenheit should equal ~90 degress Fahrenheit : 89.96 Celsius : 32.2 Raw Temp To/From Sensor A/D converter : 1738 fahrenheit : 89.96 celsius : 32.2 rawSensorValue : 1738 ==================================================================== Note changing original values will not have any affect in C++ this makes me sad :-( as a class wrapper and operator overloading is necessary... without changing the compiler... hint.... hint... fahrenheit = 10; Fahrenheit : 10 Celsius : 32.2 Raw Temp To/From Sensor A/D converter : 1738 fahrenheit : 10 celsius : 32.2 rawSensorValue : 1738 ==================================================================== No change in values :-( !!! End of data binding test // End snip program output ======================================= This was done to assist Sjepan Rajko in his work on the dataflow library (he beat me to it :-) ). Dataflow provides the event model data_binding provides the means to do data conversion between events. Brian.

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[implicit_cast]: No docs?
by Sean Hunt 27 Jul '08

27 Jul '08

implicit_cast doesn't seem to have any documentation anywhere that I can find. Is this intentional, or merely an oversight? Sean Hunt

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[math][bcp] rational.hpp doesn't get processed well by bcp
by Stjepan Rajko 26 Jul '08

26 Jul '08

Hello, boost/math/tools/rational.hpp (in trunk, at least) includes files by constructing a macro, e.g.: # define BOOST_HEADER() <BOOST_JOIN(boost/math/tools/detail/polynomial_horner1_, BOOST_MATH_MAX_POLY_ORDER).hpp> # include BOOST_HEADER() bpc doesn't seem to pick up dependencies that are included in this fashion - is it possible to include something into rational.hpp to serve as a hint to bcp on what all files might be included? Thanks, Stjepan

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How do we handle copyrights here? (Fwd: blanket-permission.txt)
by Daryle Walker 26 Jul '08

26 Jul '08

I noticed that some of my code is showing up in the inspection report. Specifically, "boost/math/common_factor_rt.hpp" and a lot of Boost.Rational. When I looked at the former file, I remembered why I never corrected those files before: I share the copyright for those files with Paul Moore, and I've never been able to find him again. (See my latest attempt below.) Unless someone else here knows how to contact him (if he's still alive), what do we do? Do we special-case those files to be skipped by the inspector? Do we try re- implementing the interface in those files so they won't contain Paul's work? Begin forwarded message: > From: "Paul Moore" <paul.moore(a)centrify.com> > Date: July 25, 2008 2:15:06 PM EDT > To: "Daryle Walker" <darylew(a)hotmail.com> > Subject: RE: [boost] blanket-permission.txt > > That's not me > > -----Original Message----- > From: Daryle Walker [mailto:darylew@hotmail.com] > Sent: Friday, July 25, 2008 11:08 AM > To: Paul Moore > Subject: [boost] blanket-permission.txt > > I got this address from looking at old Boost mailing list posts. If > you're that same Paul Moore, I wonder if you would consider adding > your > name to the BOOST_ROOT/more/blanket-permission.txt list, to allow any > material that has your copyright, in whole or in part, be shifted over > to the Boost Software License. > > I ask this because I noticed that some files I maintain are under a > list > with license check problems. (The Boost files are run over with a > batch > script that looks for such administrative problems.) I wondered why I > never fixed that problem, then when I read the file I remembered > that I > never changed it because I couldn't find you to ask permission. (The > file in particular is "boost/math/ common_factor_rt.hpp", which we > share > copyright on.) -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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Help with deficient compilers?
by Daryle Walker 26 Jul '08

26 Jul '08

I need help with fixing code in BOOST_ROOT/libs/integer/test/ integer_test.cpp. It works fine on my computer, but other ones are giving errors. I have some guesses on what's wrong, but I need suggestions on what the fixes should be. 1. I have a custom meta-function like: //========================= typedef boost::mpl::vector<unsigned char, unsigned short, unsigned int, unsigned long long> distinct_unsigned_types; typedef boost::mpl::transform< distinct_unsigned_types, boost::make_signed< boost::mpl::_1 > >::type distinct_signed_types; // List the digit counts for each integral type template < typename T > struct digits_of : boost::mpl::int_< std::numeric_limits<T>::digits > { }; typedef boost::mpl::transform< distinct_unsigned_types, digits_of< boost::mpl::_1 > >::type distinct_integral_bit_counts; //========================= I noticed that supplied meta-functions, like boost.make_unsigned, use macros in their implementations, instead of the straight implementation I use in digits_of. Now MPL says that its machinery will make sure that straight implementations work. However, I don't think it's successful on deficient compilers. Maybe I should structure digits_of with all the work-around macros. How? (I don't want to just look at the headers and guess how they work.) 2. I don't think I have SFINAE selection correct: //========================= #ifndef BOOST_NO_SFINAE template < typename ValueT, template<ValueT> class Tmpl, ValueT Value > bool print_out_template( Tmpl<Value> const &, ValueT setting, char const *template_pre_name, char const *template_post_name, typename Tmpl<Value>::type *unused = 0 ) { // Too bad the type-id expression couldn't use the compact form "*unused", // but type-ids of dereferenced null pointers throw by order of C ++ 2003, // sect. 5.2.8, para. 2 (although the result is not conceptually needed). PRIVATE_SHOW_MESSAGE( "This is " << template_pre_name << setting << template_post_name << " specialization, with type '" << typeid(typename Tmpl<Value>::type).name() << "'." ); return true; } template < typename ValueT, typename T > bool print_out_template( T const &, ValueT setting, char const *template_pre_name, char const *template_post_name ) { PRIVATE_SHOW_MESSAGE( "Looking for " << template_pre_name << setting << template_post_name << " specialization? It doesn't exist." ); return false; } #else #error "These tests cannot work without Substitution-Failure-Is-Not- An-Error" #endif //========================= The BOOST_NO_SFINAE guards didn't help, compilers still choked on this code. (I guess I'll remove those guards later.) I think that any type that doesn't have an inner "type" will only choose the false- return case. On my computer, types with an inner "type" will choose the true return case, with that case being given priority. The reports are giving errors where, when given a type with an inner "type", the two cases are considered equal, leading to an ambiguity error. How do I restructure this code? -- Daryle Walker Mac, Internet, and Video Game Junkie darylew AT hotmail DOT com

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Boost.Spirit based C++ parser
by Bruce Trask 26 Jul '08

26 Jul '08

// note to moderator, I am reposting as my original post seemed have ended up buried in "1.36 documentation" thread. Ok to repost below? Hi, I came across this wiki discussion: http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl?BoostSpiritC… Did this ever move forward or materialize? Thanks in advance. Regards, Bruce

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boost::coroutines and boost::asio
by atkinson julian 26 Jul '08

26 Jul '08

Hi, the combination of asio and coroutines would seem to represent a little bit of magic (layering a linear code model over an async event framework and without the attendant issues involved in multithreading). However the coroutine library seems to be exception throwing in an unanticipated way when performing a wait on a future<> during the execution of an asio async operation. I am following the documention and am reasonably familiar with asio from other projects - but have only just worked through some of the examples from the coroutines documention. i am using the vault freeze version of coroutines from 2006 - i understand from perusing these lists that the library author is currently rewritting boost::coroutine around a continuation framework to simplify and in the hope that the library may be an official boost inclusion. Much kudos for contributing to c++ in a significant way ;-) the documentation seems to have some errors http://www.crystalclearsoftware.com/soc/coroutine/coroutine/asio.html - guidance is given to use shared_coroutine in preference to coroutine in asio context although this is not present in the example - asio uses the boost::system error classes in the boost namespace when not freestanding - the example calls wait() on source which is a socket type rather than a future I have attempted to work up an example which looks logical - but cant get around the throw that occurs at /boost/coroutine/detail/context_base.hpp:213 // linux 2.6.23, g++ (GCC) 4.1.2 // g++ -g main.cpp -lboost_coroutine-mt -lboost_system-mt #include <iostream> #include <boost/bind.hpp> #include <boost/ref.hpp> #include <boost/coroutine/coroutine.hpp> #include <boost/coroutine/generator.hpp> #include <boost/coroutine/future.hpp> #include <boost/asio.hpp> namespace coro = boost::coroutines; using namespace coro; typedef boost::asio::io_service service_type; //typedef coro::coroutine< void()> foo_coroutine_type; //typedef coro::coroutine< void( service_type &service)> foo_coroutine_type; typedef coro::shared_coroutine< void( service_type &service)> foo_coroutine_type; void foo( foo_coroutine_type::self &self, service_type &service) { typedef boost::system::error_code error_type; typedef boost::asio::ip::tcp::resolver::query query_type; typedef boost::asio::ip::tcp::resolver::iterator iterator_type; boost::asio::ip::tcp::resolver resolver( service); query_type query( "www.boost.org", 80 ); coro::future< error_type, iterator_type> future( self); resolver.async_resolve( query, coro::make_callback( future)); assert( !future); // wait throws here --> /boost/coroutine/detail/context_base.hpp:213 coro::wait( future); assert( future); error_type &error = future->get< 0>(); if( error) std::cout << "error resolving " << error.message() << std::endl; else { iterator_type ip = future->get< 1>(); while( ip != iterator_type()) std::cout << ip->endpoint() << std::endl; } } int main() { service_type service; foo_coroutine_type cfoo( boost::bind( &foo, _1, boost::ref( service))); cfoo(); // service.post( boost::bind( &foo_coroutine_type::operator(void ), &cfoo)); service.run(); }

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Phoenix in 1.35.0
by Robert Jones 26 Jul '08

26 Jul '08

My understanding of the state of play with Phoenix is that the lovely Phoenix 2.0 is part of the not-yet-released Boost 1.36.0, and that the current release of Boost, 1.35.0 hosts Phoenix 1.2. Phoenix 2.0 has lovely documentation at http://spirit.sourceforge.net/dl_docs/phoenix-2/libs/spirit/phoenix/doc/htm… but the corresponding documentation for V1.2, at http://www.boost.org/doc/libs/1_35_0/libs/spirit/phoenix/index.html is buried inside the Spirit docs, and is not nearly as good as the v2.0 documentation. In particular the v1.2 docs are very quiet about specific include file paths, which have also changed significantly for v2.0. Is there anything I've missed in all this? ----------- Also looking through the documentation of Boost libraries in general, the quality varies widely. Am I correct in believing this is due to whether the various library authors have found time to write quality documentation? Regards, Rob. -- ACCU - Professionalism in programming - http://www.accu.org

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