September 2003 - Boost-users

using boost::mem_fn result as a parameter?
by Mark Sizer 04 Sep '03

04 Sep '03

I'm new to boost::bind and boost::mem_fn. I've read the documentation and I think I understand what they do, but I'm not sure how to use them to accomplish my task. I have a class that contains several vectors in a map. I want to put a "foreach" method on the class that will callback an arbitrary member function, of an arbitrary class, for each item in the vector. I'm stuck on the signature of that method. A quick sketch of the structure: class VectorContent { public: void dosomething(); // there are bunches more, which is why I don't // want a foreach for every possible choice. }; class VectorHolder { std::map<std::string, std::vector<VectorContent> >; std::vector<VectorContent>& rvectGet(const std::string& rksName); public: void foreach( const std::string& rksName, <WHAT?> ); }; // the callback Caller::Bar( VectorContent& vc ) { vc.dosomething(); } I see two options for the caller: // option 1 Caller::Foo1() { VectorHolder callee; // in this case, foreach uses boost::mem_fn(), not me callee.foreach( "VectorName", &this::Bar ); } // option 2 Caller::Foo2(); { VectorHolder callee; callee.foreach( "VectorName", boost::mem_fn(&this::Bar) ); } In the case of option 1, all callers must share a common base class, which they do NOT, so that the signature of VectorHolder::foreach can be: typedef void (BaseClass::* MyCallBack)(VectorContent&); Leading to: void VectorHolder::foreach( const std::string& rsName, MyCallBack callback ) { std::vector<VectorContent>& rvect = rvectGet( rsName ); std::for_each( rvect.begin(), rvect.end(), boost::mem_fn(callback) ); } In the case of option 2, I have no idea what the signature should be. But the resulting method would be: void VectorHolder::foreach( std::string& rsName, WHAT? callback ) { std::vector<VectorContent>& rvect = rvectGet( rsName ); std::for_each( rvect.begin(), rvect.end(), callback ); } Grateful for any help, - Mark P.S. If there's an "option 3", I'm up for that, too.

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Fw: [Boost-Users] Pb with threads on Mac OS X Carbon.
by Peter Dimov 04 Sep '03

04 Sep '03

Peter Dimov wrote: > degaine1966 wrote: >> Hi, >> >> I'd like to use shared pointers with CodeWarrior 8.3 in a Carbon >> application. I have some preprocessing errors, the first one being >> relative to a thread Macro being undefined: >> >> lightweight_mutex.hpp line 86 # error Unrecognized threading >> platform >> >> >> I read in boot/config/plateform/macos.hpp that Boost was thread safe >> under Carbon but apparently there is no macro to define the usable >> type of thread... > > Boost.Threads has a Mac Carbon port, but unfortunately > lightweight_mutex does not, and nobody familiar with Carbon has > contributed one.

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List host change
by Jon Kalb 04 Sep '03

04 Sep '03

Boost Users, We are moving the Boost-Users mailing list from Yahoo! Groups to a mailman based system. This means that effective immediately mail for Boost Users should be send to boost-users(a)lists.boost.org. You can manage your own subscriptions at http://lists.boost.org/mailman/listinfo.cgi/boost-users . If you have been subscribed to this list receiving individual mail messages or digest messages, then we have subscribed you to the mailman list with the same settings. If you were subscribed with either "no email" or "special emails only" then you will need to re-subscribe to the list by visiting http://lists.boost.org/mailman/listinfo.cgi/boost-users . Note that in order to send messages to this list you must be subscribed to the list. This does not mean that you must receive email from the list. You can use the "no email" setting and read and reply by newsgroup, but you must be a subscriber or your messages will not be accepted. If you have any questions or problems please contact the list moderators at boost-users-owner(a)lists.boost.org. Please note that questions and problems related to the list are off topic on this list and should only be sent to the list moderators. -- Jon Kalb SmartFriends(TM) U: Languages and Libraries Kalb(a)LibertySoft.com Sept. 26-28 http://SmartFriends.com/U Keynote: STL Creator, Alexander Stepanov

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Pb with threads on Mac OS X Carbon.
by degaine1966 03 Sep '03

03 Sep '03

Hi, I'd like to use shared pointers with CodeWarrior 8.3 in a Carbon application. I have some preprocessing errors, the first one being relative to a thread Macro being undefined: lightweight_mutex.hpp line 86 # error Unrecognized threading platform I read in boot/config/plateform/macos.hpp that Boost was thread safe under Carbon but apparently there is no macro to define the usable type of thread... Any help appreciated, Bruno

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Filesystem Lib Feature Request
by Robert W. Johnstone 03 Sep '03

03 Sep '03

Hello, Has any thought been given to member functions for the path class for handling filename extensions? It should be easy to add code for most systems to extract or change the extension. Thanks, ------------------------------------------ Robert Johnstone Simon Fraser University http://www.sfu.ca/~rjohnsto/

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ostream_iterator and std::copy - better solutions?
by Jeff Flinn 03 Sep '03

03 Sep '03

Before rolling my own, does boost have a facility to stream out an iterator range without the dangling delimiter at the end? For example std::ostream& operator<<( std::ostream& s, const MyClass& aC ) { const std::string lDelim( "," ); std::vector<int> lInts; lInts.push_back(1); lInts.push_back(2); lInts.push_back(3); std::ostream_iterator<int> lItr( s, lDelim.c_str() ); std::copy( lInts.begin(), lInts.end(), lItr ); } yields: 1,2,3, I'm thinking something like the following usage would be nice: s << range_streamer( lInts.begin(), lInts.end(), "{", "," "}" ); yielding: {1,2,3} Any thoughts? -- Jeff Flinn Applied Dynamics, International

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RE: [Boost-Users] boost lambda examples
by Paul Grenyer 03 Sep '03

03 Sep '03

Hi Matt > > >for_each( v.begin(), v.end(), cout << *_1 << '\n' ); > > >I get the following errors: > That only makes sense with vector<int*>... as per the example, from > memory... > I think you meant vp.begin() etc. Yes, that's it! So what I actually wanted was: for_each( v.begin(), v.end(), cout << _1 << '\n' ); That'll teach me copy code from two different examples without applying my brain to it. Thanks, Matt! Regards Paul Paul Grenyer Email: pjgrenyer(a)iee.org Web: www.paulgrenyer.co.uk You cant buy time, but you can sell your soul and the closest thing to heaven is to Rock n' Roll.

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boost lambda examples
by paulgrenyer 03 Sep '03

03 Sep '03

Hi MSVC 7.1, Windows 2000 I'm trying to get to grips with the boost lambda library. I've managed to get the first example to work: #include <boost/lambda/lambda.hpp> #include <iostream> #include <cstdlib> #include <list> #include <algorithm> int main() { using namespace std; using namespace boost::lambda; list<int> v(10); for_each(v.begin(), v.end(), _1 = 12 ); return EXIT_SUCCESS; } but when I add the following line (also from the docs): for_each( v.begin(), v.end(), cout << *_1 << '\n' ); I get the following errors: error C2039: 'reference' : is not a member of 'std::iterator_traits<int>' error C2146: syntax error : missing ';' before identifier 'type' error C2501: 'boost::lambda::detail::contentsof_type<A>::type' : missing storage-class or type specifiers error C2039: 'type' : is not a member of 'boost::lambda::detail::contentsof_type<A>' error C2146: syntax error : missing ';' before identifier 'type' I've tried including some the other Lambda headers but this didn't improve the situation. Regards Paul

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RE: [Boost-Users] boost lambda examples
by Hurd, Matthew 03 Sep '03

03 Sep '03

>From: paulgrenyer [mailto:pjgrenyer@iee.org] >Subject: [Boost-Users] boost lambda examples >for_each( v.begin(), v.end(), cout << *_1 << '\n' ); >I get the following errors: That only makes sense with vector<int*>... as per the example, from memory... I think you meant vp.begin() etc. Cheers, Matt.

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"invalid token pasting" macro bug
by James W. Walker 03 Sep '03

03 Sep '03

When I use Spirit with CodeWarrior 9 (just released), I get a bunch of warnings as shown below. The CodeWarrior release notes explain that "According to the language standard, the '##' token pasting operator can only generate other tokens. This warning indicates when a paste was found that did not result in a token. The code will still compile as it did previously, but it may be a useful hint if the compiler emits an error later on." Warning : invalid token pasting of 'BOOST_PP_LIST_FIRST_I' and '(' (included from: expanding macro 'BOOST_PP_LIST_FIRST' expanding macro 'BOOST_PP_LIST_FOR_EACH_I_M_D' expanding macro 'BOOST_PP_LIST_FOR_EACH_I_M' expanding macro 'BOOST_PP_FOR_1_C' expanding macro 'BOOST_PP_FOR_1' expanding macro 'BOOST_PP_LIST_FOR_EACH_I' type_traits.hpp:58 composite.ipp:16 composite.hpp:15 directives.hpp:27 numerics.hpp:19 core.hpp:34 spirit.hpp:30 ParseCalcLine.cp:5) type_with_alignment.hpp line 55 on_ptr, BOOST_PP_NIL)))))))))))) -- <http://www.jwwalker.com/>

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