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RE: [Boost-Users] Re: Use a shared_ptr as a 'backpointer'?
by dick.bridges＠tais.com 30 Sep '02

30 Sep '02

1) There are circumstances where the 'creator' should stick around as long as one or more 'creations' still exist (e.g., a [network] session that's created various asynchronous conversations). 2) I haven't had time to check, but I think this is the as-yet-not-but-soon-to-be-released implementation of intrusive pointers. Interesting: search google for "intrusive pointer" (quotes not required). I got five hits - all of the URLs start with www.boost.org/. BTW: Really slick. Trying to figure out where to keep "THE POINTER" was driving me nuts. I'd completely forgotten about intrusive pointers. Thanks. A *LOT*. Mark Storer <mstorer@cardiff To: "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> .com> cc: Subject: RE: [Boost-Users] Re: Use a shared_ptr as a 'backpointer'? 09/30/2002 09:36 AM Please respond to Boost-Users I've got a comment and a question... 1) Couldn't the "backpointer" just be a constant reference? Backpointers, in my mind, don't have anything to do with ownership, so a shared_ptr woulnd't be appropriate. 2) shared_from_this? I can't find that one in any of the headers or docs I downloaded with 1.28. I did find shared_count in (oddly enough) shared_count.hpp, which looks like it would prevent two seperate shared_ptr's from causing a double-delete... pretty slick, but I couldn't find any docs on it. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: David Abrahams [mailto:yg-boost-users@m.gmane.org] Sent: Sunday, September 29, 2002 4:12 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] Re: Use a shared_ptr as a 'backpointer'? <dick.bridges(a)tais.com> wrote in message news:OF699D7956.EED22A4F-ON88256C43.00722AD0@tais.net... > I run into situations where it's useful for an object to have a > 'backpointer' to the object instance that created it (example below). Is > there a pattern/idiom for doing this using shared_ptr? Or maybe I need to > re-think the idea of the backpointer in the first place? > class Bar; class Foo { public: Foo(shared_ptr<Bar>); private: shared_ptr<Bar> p; }; class Bar : boost::shared_count { void doit() { new Foo(boost::shared_from_this(this)); // <<< new Foo(this) obviously won't work. } }; HTH, Dave -- ----------------------------------------------------------- David Abrahams * Boost Consulting dave(a)boost-consulting.com * http://www.boost-consulting.com Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: [Boost-Users] Re: Use a shared_ptr as a 'backpointer'?
by Mark Storer 30 Sep '02

30 Sep '02

I've got a comment and a question... 1) Couldn't the "backpointer" just be a constant reference? Backpointers, in my mind, don't have anything to do with ownership, so a shared_ptr woulnd't be appropriate. 2) shared_from_this? I can't find that one in any of the headers or docs I downloaded with 1.28. I did find shared_count in (oddly enough) shared_count.hpp, which looks like it would prevent two seperate shared_ptr's from causing a double-delete... pretty slick, but I couldn't find any docs on it. --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: David Abrahams [mailto:yg-boost-users@m.gmane.org] Sent: Sunday, September 29, 2002 4:12 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] Re: Use a shared_ptr as a 'backpointer'? <dick.bridges(a)tais.com> wrote in message news:OF699D7956.EED22A4F-ON88256C43.00722AD0@tais.net... > I run into situations where it's useful for an object to have a > 'backpointer' to the object instance that created it (example below). Is > there a pattern/idiom for doing this using shared_ptr? Or maybe I need to > re-think the idea of the backpointer in the first place? > class Bar; class Foo { public: Foo(shared_ptr<Bar>); private: shared_ptr<Bar> p; }; class Bar : boost::shared_count { void doit() { new Foo(boost::shared_from_this(this)); // <<< new Foo(this) obviously won't work. } }; HTH, Dave -- ----------------------------------------------------------- David Abrahams * Boost Consulting dave(a)boost-consulting.com * http://www.boost-consulting.com Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: [Boost-Users] shared_ptr and counted_base
by Hickman, Greg 30 Sep '02

30 Sep '02

> I was looking through the latest boost documentation, trying Where is the documentation to which you refer? Is this a development doc or part of the ordinary user docs (if the latter, I don't know where to find it)? -Greg

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Problem using 'shared_ptr<T>::operator impl-defined-type()'
by Hickman, Greg 30 Sep '02

30 Sep '02

With Borland 5.5.1, I'm not having any luck using a shared_ptr in a boolean context. The compiler complains that the 'if' condition below contains an "Illegal structure operation". Is this a known deficiency with my compiler? -Greg Hickman #include <boost/shared_ptr.hpp> int main(int argc, char* argv[]) { boost::shared_ptr<int> intp; if (intp) // error here ; return 0; }

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RE: [Boost-Users] Returning a boost::scoped_lock by value
by Darryl Green 30 Sep '02

30 Sep '02

This issue has come up before on the development list (search for Boost.Threads Locking Delima). I'm not sure that it was resolved satisfactorily - move semantics for scoped_locks seemed to be the answer, but I think there were problems actually implementing that. The intent was that if move couldn't be implemented, then the mutex lock methods would have to be exposed. > -----Original Message----- > From: Raoul Gough [mailto:yg-boost-users@m.gmane.org] > Sent: Friday, 27 September 2002 9:44 PM > To: boost-users(a)yahoogroups.com > Subject: [Boost-Users] Returning a boost::scoped_lock by value > > > > boost::scoped_lock is non-copyable, so it is impossible to > return one from a function by value. However, I would like to > be able to do something like this: > > mt::holder<std::ostream> logStream; > > logStream() << "Hello world\n"; > > where the operator() returns a proxy object that contains a > scoped_lock and a pointer to the data (the ostream). What I > currently have is this: > > (mt::proxy<std::ostream> (logStream)) << "Hello world\n"; > > So the client code has to know what type the proxy object is > and construct one itself. If scoped_lock would provide access > to its associated mutex object, this wouldn't be a necessary, > because the proxy object could then have a copy-constructor, > and operator() in the holder template would look like this: > > proxy<T> operator() () > { > proxy<T> temp (*this); > return temp; > } > > The proxy copy constructor would unlock() the original lock > and construct the copy using the original's mutex (which is > the part that can't currently work, because there is no > public access to a lock's mutex). Assuming that the compiler > implements the NRVO, the unlock/lock sequence wouldn't > actually happen, and the client code just gets its proxy > object constructed for it. If the compiler doesn't implement > the NRVO, the code still works, but is less efficient. > > I guess exposing the raw mutex from scoped_lock would break > an important level of encapsulation. Still, it would be kind > of nice in this case. Maybe if proxy<T> were part of the > library and made a friend of scoped_lock? The only other > alternative I've come up with is to allocate the lock on the > heap and return an object containing a std::auto_ptr (which > makes usage easier, but less efficient). Any comments or suggestions? > > Regards, > Raoul Gough. > > > // Returnable proxy template > > template<typename T> > class proxy > { > boost::mutex::scoped_lock mLock; > T *mPtr; > > boost::mutex &release() > { > mLock.unlock(); > return mLock.mutex(); // <<<< doesn't work > } > > public: > > proxy (proxy &other) > : mLock (other.release()) > , mPtr (other.mPtr) > { > } > > // ... > }; > > > > > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> Home Selling? Try Us! > http://us.click.yahoo.com/QrPZMC/iTmEAA/MVfIAA> /EbFolB/TM > > > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > >

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RE: [Boost-Users] newbie Question about the macro BOOST_JOIN
by scleary＠jerviswebb.com 28 Sep '02

28 Sep '02

> From: zhangwusheng [mailto:yg-boost-users@m.gmane.org] > > Hi,all, > In file suffix.hpp there are lines: > > #define BOOST_JOIN( X, Y ) BOOST_DO_JOIN( X, Y ) > #define BOOST_DO_JOIN( X, Y ) BOOST_DO_JOIN2(X,Y) > #define BOOST_DO_JOIN2( X, Y ) X##Y > > > why donot we define such macro instead: > #define BOOST_JOIN( X, Y ) X##Y The idea behind BOOST_JOIN is to force the preprocessor to scan the macro parameters for replacement before merging the results with ##. So, it changes the meaning if one of the parameters is a macro: #define Z_BOOST_JOIN(X, Y) X##Y Z_BOOST_JOIN(id_, __LINE__) // Expands to "id___LINE__" BOOST_JOIN(id_, __LINE__) // Expands to "id_13" if __LINE__ is 13 However, I'm not sure why BOOST_DO_JOIN2 is used; it seems to me that only one layer of indirection should work. I assume it's to work around some compiler's non-conforming preprocessor. -Steve

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Boost::UBLAS problems
by pecos_outwest 27 Sep '02

27 Sep '02

Hi Folks, I have been experimenting with the new BOOST linear algebra section boost/numeric/ublas I have been running the examples and benchmark programs bench1 and test1 provided with the distribution. Both programs compile and link perfectly they also run to completion; but they only run one time ! I cannot run a second time. It looks like the executable isn't even starting. Has anyone found this problem and found the solution I am using Microsoft VC6 compiler on a PC Thanks...Pecos

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shared_ptr and counted_base
by Bobby Thomale 27 Sep '02

27 Sep '02

I was looking through the latest boost documentation, trying to find a way to get a shared_ptr from a this pointer of an object that already is contained by a shared_ptr somewhere, without knowing about that other shared_ptr out there. I noticed this intriguing comment in the latest docs: > [This constructor has been changed to a template in order to remember the > actual pointer type passed. The destructor will call delete with the same > pointer, complete with its original type, even when T does not have a virtual > destructor, or is void. > > In the current implementation, if p is convertible to counted_base *, > shared_ptr will use the embedded reference count supplied by counted_base. > This is an (experimental) attempt to provide a way for shared_ptr to be > constructed from a raw pointer such as this. A free function > shared_from_this(q) performs the conversion when q is convertible to > counted_base const *. > > The optional intrusive counting employed by the current implementation allows > shared_ptr to interoperate with intrusive_ptr, an experimental generic > intrusive-counted smart pointer. > > Another possible implementation is to use a global pointer-to-count map > instead of intrusive counting. shared_from_this would no longer be O(1), which > is a concern for some users, although I do not expect any performance > problems, since the operation is rare. Maintaining a global map is difficult; > it needs to be initialized before any shared_ptr instances are constructed, > and the initialization needs to be thread safe. In addition, under the Windows > dynamic library model, it is possible for several maps to exist. > > It is not yet clear which implementation should be used, or whether the > specification should allow both; nevertheless, the ability to make a > shared_ptr from this is considered essential by experienced smart pointer > users.] That looks like EXACTLY what I am looking for. But a couple things aren't clear to me: 1. Usage - The docs tell me its there but don't really say explicitly how to use it. It looks like, to use this, all I have to do is subclass boost::counted_base in my class that is being shared. Then I can just call shared_from_this to get another shared_ptr out of myself and it should just work. If that is all I have to do, then awesome! Is it really that easy or is there another step I am missing? 2. The word "experimental" above scares me. :-) If I use the counted_base subclass and shared_from_this function, is that code going to break later on if you guys change your minds? Anyway, I just want to reiterate what the comment at the end says, that the ability to make a shared_ptr from *this is essential to use these things. :-) -- Bobby --------------------------------------------------------------------- Bobby Thomale Senior Software Developer Inoveon Corporation http://www.inoveon.com/ ---------------------------------------------------------------------

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Returning a boost::scoped_lock by value
by Raoul Gough 27 Sep '02

27 Sep '02

boost::scoped_lock is non-copyable, so it is impossible to return one from a function by value. However, I would like to be able to do something like this: mt::holder<std::ostream> logStream; logStream() << "Hello world\n"; where the operator() returns a proxy object that contains a scoped_lock and a pointer to the data (the ostream). What I currently have is this: (mt::proxy<std::ostream> (logStream)) << "Hello world\n"; So the client code has to know what type the proxy object is and construct one itself. If scoped_lock would provide access to its associated mutex object, this wouldn't be a necessary, because the proxy object could then have a copy-constructor, and operator() in the holder template would look like this: proxy<T> operator() () { proxy<T> temp (*this); return temp; } The proxy copy constructor would unlock() the original lock and construct the copy using the original's mutex (which is the part that can't currently work, because there is no public access to a lock's mutex). Assuming that the compiler implements the NRVO, the unlock/lock sequence wouldn't actually happen, and the client code just gets its proxy object constructed for it. If the compiler doesn't implement the NRVO, the code still works, but is less efficient. I guess exposing the raw mutex from scoped_lock would break an important level of encapsulation. Still, it would be kind of nice in this case. Maybe if proxy<T> were part of the library and made a friend of scoped_lock? The only other alternative I've come up with is to allocate the lock on the heap and return an object containing a std::auto_ptr (which makes usage easier, but less efficient). Any comments or suggestions? Regards, Raoul Gough. // Returnable proxy template template<typename T> class proxy { boost::mutex::scoped_lock mLock; T *mPtr; boost::mutex &release() { mLock.unlock(); return mLock.mutex(); // <<<< doesn't work } public: proxy (proxy &other) : mLock (other.release()) , mPtr (other.mPtr) { } // ... };

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[BGL]: Iterating through internal properties of specific value
by Björn Lindberg 27 Sep '02

27 Sep '02

I have a BGL graph (adjacency_list). I use it to represent a tree, and so I have an internal vertex property of type enum representing the node type, ie ROOT, LEAF, INNER. Now, I would like a way to access only the leaves of a tree, preferrably through iterators. I can't think of any good way to accomplish this, except possibly by writing new iterator classes which would internally keep track of a property map and thus hide traversal of the non-leaf nodes from the code using the iterators. This seems like a cumbersome approach though, and I'm hoping there is a simpler way? Björn

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RE: [Boost-Users] metaprogramming and MPL
by Aleksey Gurtovoy 27 Sep '02

27 Sep '02

Ihsan Ali Al Darhi wrote: > I am interested in metaprogramming and Boost mpl. But I can't find a > complete doc about the two subjects together. Where on the > net I can such info? It's not exactly a "complete doc" yet, but it's the most of that is publicly available to the moment - http://www.mywikinet.com/mpl/. Note that MPL sources in the CVS main trunk are more up-to-date than the .zip archive available for download from the library's page. HTH, Aleksey

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newbie Question about the macro BOOST_JOIN
by zhangwusheng 27 Sep '02

27 Sep '02

Hi,all, In file suffix.hpp there are lines: #define BOOST_JOIN( X, Y ) BOOST_DO_JOIN( X, Y ) #define BOOST_DO_JOIN( X, Y ) BOOST_DO_JOIN2(X,Y) #define BOOST_DO_JOIN2( X, Y ) X##Y why donot we define such macro instead: #define BOOST_JOIN( X, Y ) X##Y thanks in advance.

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RE: [Boost-Users] bind: I just keep trying...
by dick.bridges＠tais.com 26 Sep '02

26 Sep '02

<datapoints> MSDN January 2002 contains only the 'old' level 1 definition. Q113417 from that same source says the compiler generates the warning with both the /Ze and /Za switches. The 'online' MSDN contains only the level 3 definition. You're running SP3 and I'm running SP5. </datapoints> THEREFORE: #pragma warning(disable : 4097) // ;) #include <boost/function.hpp> #pragma warning(default : 4097) Thanks for the input. "Jim.Hyslop" <jim.hyslop@leit To: "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> ch.com> cc: Subject: RE: [Boost-Users] bind: I just keep trying... 09/26/2002 01:01 PM Please respond to Boost-Users dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] wrote: > Well, that helped A LOT. The only warnings I get now are: > > <warnings> > c:\boost\function.hpp(451) : warning C4097: typedef-name > 'base_type' used > as synonym for class-name > 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, > `template-parameter268',`template-parameter269',`template-para > meter270'>' > The warning level is 4: I'm paranoid. Can these safely be ignored? According to the MSDN: ---------------- begin quote from MSDN ----------------------------- Compiler Warning (level 3) C4097 typedef-name 'identifier1' used as synonym for class-name 'identifier2' A typedef name which names a class is itself a class name. However, only a class declared without a tag can be named. In the following line of code the typedef name P is promoted to class name but Q is not. typedef struct { int member; } P, Q; Q remains a normal typedef name and a synonym for the class. The following example causes this warning: typedef struct _T { int i; } T; struct U : T { int j; }; // warning struct V : _T { int j; }; // OK ------------------------ end quote from MSDN ------------------------- However, when I tried compiling the example, MSVC6 SP3 at warning level 4 was completely silent. So I'm really confused now - is it a problem or not? My instinct says no, but I've been wrong before. -- Jim Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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Re: [Boost-Users] bind: I just keep trying...
by dick.bridges＠tais.com 26 Sep '02

26 Sep '02

Well, that helped A LOT. The only warnings I get now are: <warnings> c:\boost\function.hpp(451) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled c:\boost\function.hpp(452) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled c:\boost\function.hpp(453) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled </warnings> The warning level is 4: I'm paranoid. Can these safely be ignored? Douglas Gregor <gregod(a)cs.rpi.e To: Boost-Users(a)yahoogroups.com du> cc: Subject: Re: [Boost-Users] bind: I just keep trying... 09/26/2002 10:09 AM Please respond to Boost-Users On Thursday 26 September 2002 01:02 pm, dick.bridges(a)tais.com wrote: > Thanks. I changed the map to: > typedef map<session_id, boost::function<long, Y*, X*> > MyMessageMap; > > No errors but enough warnings to choke a horse. Have I just been nailed by > VC6SP4? If so, I think I'll just give up and map the session-ids to Y*s. > %>( > > Thanks in advance for any suggestions. I've never seen that warning before. What warning level are you using? Anyway, just change boost::function<long, Y*, X*> to boost::function2<long, Y*, X*> Then you'll be in conformance with upcoming Boost releases (Boost 1.29.0 deprecates the former syntax), and the warning should disappear. Doug Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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RE: [Boost-Users] bind: I just keep trying...
by Jim.Hyslop 26 Sep '02

26 Sep '02

dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] wrote: > Well, that helped A LOT. The only warnings I get now are: > > <warnings> > c:\boost\function.hpp(451) : warning C4097: typedef-name > 'base_type' used > as synonym for class-name > 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, > `template-parameter268',`template-parameter269',`template-para > meter270'>' > The warning level is 4: I'm paranoid. Can these safely be ignored? According to the MSDN: ---------------- begin quote from MSDN ----------------------------- Compiler Warning (level 3) C4097 typedef-name 'identifier1' used as synonym for class-name 'identifier2' A typedef name which names a class is itself a class name. However, only a class declared without a tag can be named. In the following line of code the typedef name P is promoted to class name but Q is not. typedef struct { int member; } P, Q; Q remains a normal typedef name and a synonym for the class. The following example causes this warning: typedef struct _T { int i; } T; struct U : T { int j; }; // warning struct V : _T { int j; }; // OK ------------------------ end quote from MSDN ------------------------- However, when I tried compiling the example, MSVC6 SP3 at warning level 4 was completely silent. So I'm really confused now - is it a problem or not? My instinct says no, but I've been wrong before. -- Jim

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RE: [Boost-Users] bind: I just keep trying...
by dick.bridges＠tais.com 26 Sep '02

26 Sep '02

Thanks. I changed the map to: typedef map<session_id, boost::function<long, Y*, X*> > MyMessageMap; No errors but enough warnings to choke a horse. Have I just been nailed by VC6SP4? If so, I think I'll just give up and map the session-ids to Y*s. %>( Thanks in advance for any suggestions. <warnings> --------------------Configuration: MyProject - Win32 Debug-------------------- Compiling... Z.cpp c:\boost\function.hpp(451) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled c:\boost\function.hpp(452) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled c:\boost\function.hpp(453) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>::function1<R,T0, `template-parameter268',`template-parameter269',`template-parameter270'>' c:\boost\function.hpp(497) : see reference to class template instantiation 'boost::function<R,T1,T2,T3,T4,T5,T6,T7,T8,T9,T10>' being compiled c:\boost\function.hpp(451) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,st ruct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable>::fun ction2<int,class Y *,class X *,struct boost::empty_function_policy,struct boost::empty_function_mixin,class std::allocator<class boost::function_base> >' c:\program files\microsoft visual studio\vc98\include\utility(26) : see reference to class template instantiation 'boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::fu nction::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::funct ion::unusable>' being compiled c:\program files\microsoft visual studio\vc98\include\xtree(28) : see reference to class template instantiation 'std::pair<class session_id const ,class boost::function<int,class Y *,class X *,struct boost::detail:: function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::fun ction::unusable,struct boost::detail::function::unusable> >' being compiled c:\program files\microsoft visual studio\vc98\include\map(46) : see reference to class template instantiation 'std::_Tree<class session_id,struct std::pair<class session_id const ,class boost::function<int,class Y *,c lass X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::functi on::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> >,struct std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct b oost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >::_K fn,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unus able,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >' being compiled c:\src\inc\Z.h(240) : see reference to class template instantiation 'std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable,struct boost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable> > >' being compiled c:\boost\function.hpp(452) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,st ruct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable>::fun ction2<int,class Y *,class X *,struct boost::empty_function_policy,struct boost::empty_function_mixin,class std::allocator<class boost::function_base> >' c:\program files\microsoft visual studio\vc98\include\utility(26) : see reference to class template instantiation 'boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::fu nction::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::funct ion::unusable>' being compiled c:\program files\microsoft visual studio\vc98\include\xtree(28) : see reference to class template instantiation 'std::pair<class session_id const ,class boost::function<int,class Y *,class X *,struct boost::detail:: function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::fun ction::unusable,struct boost::detail::function::unusable> >' being compiled c:\program files\microsoft visual studio\vc98\include\map(46) : see reference to class template instantiation 'std::_Tree<class session_id,struct std::pair<class session_id const ,class boost::function<int,class Y *,c lass X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::functi on::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> >,struct std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct b oost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >::_K fn,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unus able,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >' being compiled c:\src\inc\Z.h(240) : see reference to class template instantiation 'std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable,struct boost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable> > >' being compiled c:\boost\function.hpp(453) : warning C4097: typedef-name 'base_type' used as synonym for class-name 'function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,st ruct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable>::fun ction2<int,class Y *,class X *,struct boost::empty_function_policy,struct boost::empty_function_mixin,class std::allocator<class boost::function_base> >' c:\program files\microsoft visual studio\vc98\include\utility(26) : see reference to class template instantiation 'boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::fu nction::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::funct ion::unusable>' being compiled c:\program files\microsoft visual studio\vc98\include\xtree(28) : see reference to class template instantiation 'std::pair<class session_id const ,class boost::function<int,class Y *,class X *,struct boost::detail:: function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::fun ction::unusable,struct boost::detail::function::unusable> >' being compiled c:\program files\microsoft visual studio\vc98\include\map(46) : see reference to class template instantiation 'std::_Tree<class session_id,struct std::pair<class session_id const ,class boost::function<int,class Y *,c lass X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::functi on::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> >,struct std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct b oost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struc t boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >::_K fn,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unus able,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable> > >' being compiled c:\src\inc\Z.h(240) : see reference to class template instantiation 'std::map<class session_id,class boost::function<int,class Y *,class X *,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable,struct boost::detail::function::unusable>,struct std::less<class session_id>,class std::allocator<class boost::function<int,class Y *,class X *,struct boost::detail::function::unusable,struct boost::detail::function ::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::unusable,struct boost::detail::function::u nusable> > >' being compiled Z.obj - 0 error(s), 6 warning(s) </warnings> Tom Matelich <tmatelich@zetec To: "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> .com> cc: Subject: RE: [Boost-Users] bind: I just keep trying... 09/26/2002 08:40 AM Please respond to Boost-Users I think the best solution for you would be to put boost::function<short>'s in your map. Look at the example in the bind documentation at http://www.boost.org/libs/bind/bind.html#with_boost_function Tom > -----Original Message----- > From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] > Sent: Thursday, September 26, 2002 7:57 AM > To: Boost-Users(a)yahoogroups.com > Subject: RE: [Boost-Users] bind: I just keep trying... > > > > I'm trying to store member function pointers. For purposes of this > discussion, the key is an int. > > <context> > X is the virtual base class for polymorphic message classes. > all messages have a session-d attribute > > Ys are instances of classes derived from a virtual message hanler base > class. > foo() is the message handler function. > > Z is the 'message pump' that dispatches messages to Ys based upon the > session-id. > > Y instances insert make_pair(session-id, message_handler) > pairs into the > map. > (I think _1 is 'this' during the insert.) > > Z calls the Y instance message-handler using the session-id > key to the > map. > </context> > > > > > > > Mark Storer > > > <mstorer@cardiff To: > "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> > > .com> cc: > > > Subject: RE: > [Boost-Users] bind: I just keep trying... > > 09/25/2002 04:47 > > > PM > > > Please respond > > > to Boost-Users > > > > > > > > > > > > > I'm a little confused as to what you're aiming for here... a > map of ints to > function pointers (that can point to Y::foo)? > > This should do the trick, provided I'm recalling my function pointer > declarations correctly > std::map<int, short()(*X)> > > Further boost::bind creates an INSTANCE of a functor. Giving > the compiler > an instance when it wants a type is not a good way to keep it happy. > > Now if what you're actually after is calling Y::foo on a > colleciton of Y's, > then you don't need a collection of function pointers for > each instance in > the first place, which is where bind comes in. According to my flimsy > understanding of bind (I haven't used it yet), this should do > the trick: > > X someX; > std::vector<Y> &wise = BuildYs(); // wise == plural of Y > > std::for_each( > wise.begin(), > wise.end(), > boost::bind<short>(&Y::foo, &someX) > ); > > If you want the X parameter to vary from one call of foo to > the next, I > suggest rolling your own loop... or incorporating the X* into > Y, at which > point you can get rid of the X* parameter, and use > boost::bind(&Y::foo), or > std::mem_fun(&Y::foo). > > --Mark Storer > Software Engineer > Cardiff Software > > #include <disclaimer> > typedef std::disclaimer<Cardiff> Discard; > > > -----Original Message----- > From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] > Sent: Wednesday, September 25, 2002 4:08 PM > To: boost-users(a)yahoogroups.com > Subject: [Boost-Users] bind: I just keep trying... > > > Everytime I think I have a clue, I'm reminded how little I REALLY > understand. > > <error compiler='VC6SP4'> > 'map' : invalid template argument for '_Ty', type expected > </error> > > <snippet> > struct X > { > } > > struct Y > { > short foo(X*); > } > > struct Z > { > map<int, bind(&Y::foo, _1, _2) > myMap; > } > </snippet> > > I thought I saw how to do this somewhere on the website but I > sure can't > find it now. Any help GREATFULLY appreciated. > > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > > > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Home Selling? Try Us! > http://us.click.yahoo.com/QrPZMC/iTmEAA/MVfIAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. ----------------------------------------------------------------------- Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

2 1

RE: [Boost-Users] std::swap() vs boost::swap()
by scleary＠jerviswebb.com 26 Sep '02

26 Sep '02

> From: Galante Michele [mailto:M.Galante@centrosistemi.it] > > > Argument-dependent lookup will ensure that any 'swap' functions in the > > namespaces used by 'T' will be included in the set of known swap functions, > > along with std::swap. Overloading and partial ordering of function templates > > will then take over to ensure that the appropriate swap(a, b) will be called > > (even if it is boost::swap). > > I did not know this. I suppose this is the "Koenig lookup" that Steve > mentions in his reply. > I've tried this and it works with GCC 3.1 but unfortunately > not with BCC 5.6 > (so I think it is a Borland bug). Yes "Koenig lookup" is "argument-dependent lookup", and sadly several compilers still do not implement it. There's a workaround for the lack of Borland's support: using std::swap; // This should have been in my example to begin with... using boost::swap; swap(x, y); Which works on GCC 3.1.1 and BCC 5.6, and I would imagine any other compiler as well. The downside is that you have to list in your "generic" function all the namespaces that it can be used with -- which then makes it not-very-generic on compilers without Koenig lookup. But it's better than nothing... -Steve

1 0

R: [Boost-Users] std::swap() vs boost::swap()
by Galante Michele 26 Sep '02

26 Sep '02

> Argument-dependent lookup will ensure that any 'swap' functions in the > namespaces used by 'T' will be included in the set of known swap functions, > along with std::swap. Overloading and partial ordering of function templates > will then take over to ensure that the appropriate swap(a, b) will be called > (even if it is boost::swap). I did not know this. I suppose this is the "Koenig lookup" that Steve mentions in his reply. I've tried this and it works with GCC 3.1 but unfortunately not with BCC 5.6 (so I think it is a Borland bug). Thank you Steve and Doug. Michele Galante Zucchetti Centro Sistemi s.p.a. m.galante(a)centrosistemi.it

1 0

RE: [Boost-Users] bind: I just keep trying...
by Tom Matelich 26 Sep '02

26 Sep '02

I think the best solution for you would be to put boost::function<short>'s in your map. Look at the example in the bind documentation at http://www.boost.org/libs/bind/bind.html#with_boost_function Tom > -----Original Message----- > From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] > Sent: Thursday, September 26, 2002 7:57 AM > To: Boost-Users(a)yahoogroups.com > Subject: RE: [Boost-Users] bind: I just keep trying... > > > > I'm trying to store member function pointers. For purposes of this > discussion, the key is an int. > > <context> > X is the virtual base class for polymorphic message classes. > all messages have a session-d attribute > > Ys are instances of classes derived from a virtual message hanler base > class. > foo() is the message handler function. > > Z is the 'message pump' that dispatches messages to Ys based upon the > session-id. > > Y instances insert make_pair(session-id, message_handler) > pairs into the > map. > (I think _1 is 'this' during the insert.) > > Z calls the Y instance message-handler using the session-id > key to the > map. > </context> > > > > > > > Mark Storer > > > <mstorer@cardiff To: > "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> > > .com> cc: > > > Subject: RE: > [Boost-Users] bind: I just keep trying... > > 09/25/2002 04:47 > > > PM > > > Please respond > > > to Boost-Users > > > > > > > > > > > > > I'm a little confused as to what you're aiming for here... a > map of ints to > function pointers (that can point to Y::foo)? > > This should do the trick, provided I'm recalling my function pointer > declarations correctly > std::map<int, short()(*X)> > > Further boost::bind creates an INSTANCE of a functor. Giving > the compiler > an instance when it wants a type is not a good way to keep it happy. > > Now if what you're actually after is calling Y::foo on a > colleciton of Y's, > then you don't need a collection of function pointers for > each instance in > the first place, which is where bind comes in. According to my flimsy > understanding of bind (I haven't used it yet), this should do > the trick: > > X someX; > std::vector<Y> &wise = BuildYs(); // wise == plural of Y > > std::for_each( > wise.begin(), > wise.end(), > boost::bind<short>(&Y::foo, &someX) > ); > > If you want the X parameter to vary from one call of foo to > the next, I > suggest rolling your own loop... or incorporating the X* into > Y, at which > point you can get rid of the X* parameter, and use > boost::bind(&Y::foo), or > std::mem_fun(&Y::foo). > > --Mark Storer > Software Engineer > Cardiff Software > > #include <disclaimer> > typedef std::disclaimer<Cardiff> Discard; > > > -----Original Message----- > From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] > Sent: Wednesday, September 25, 2002 4:08 PM > To: boost-users(a)yahoogroups.com > Subject: [Boost-Users] bind: I just keep trying... > > > Everytime I think I have a clue, I'm reminded how little I REALLY > understand. > > <error compiler='VC6SP4'> > 'map' : invalid template argument for '_Ty', type expected > </error> > > <snippet> > struct X > { > } > > struct Y > { > short foo(X*); > } > > struct Z > { > map<int, bind(&Y::foo, _1, _2) > myMap; > } > </snippet> > > I thought I saw how to do this somewhere on the website but I > sure can't > find it now. Any help GREATFULLY appreciated. > > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > > > > > > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> > Home Selling? Try Us! > http://us.click.yahoo.com/QrPZMC/iTmEAA/MVfIAA/EbFolB/TM > -------------------------------------------------------------- > -------~-> > > Info: <http://www.boost.org> > Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> > Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > ----------------------------------------------------------------------- DISCLAIMER: Information contained in this message and/or attachment(s) may contain confidential information of Zetec, Inc. If you have received this transmission in error, please notify the sender by return email. -----------------------------------------------------------------------

1 0

intrusive_ptr
by nobody 26 Sep '02

26 Sep '02

Hi! There is a intrusive_ptr.cpp in boost 1.28, but I did not find any doc for that... exept for in the timing . Why? Guessing from the name, intrusive_ptr requires the pointed-to object to store the reference count or something like that, doesn't it? And what does anybody think of typedefing std::auto_ptr to boost::single_ptr? Finally I have a suggestion for a new type of smart pointer one could call "notifying_ptr": Sometimes all weak pointing objects need to be notified when the object pointed to is destroyed: e.g. in a game some units are set to attack some building, so they store a weak_ptr to the building, but when that building is destroyed, it would be easier to implement and faster performing, if the units got a message so they can look for a new target, instead of having strong pointers, marking the building as dead, and polling for that state every time the unit does something. It could be quite some time until all units have realized that the building is gone and it really can be released from memory. Regards

2 2

RE: [Boost-Users] bind: I just keep trying...
by dick.bridges＠tais.com 26 Sep '02

26 Sep '02

I'm trying to store member function pointers. For purposes of this discussion, the key is an int. <context> X is the virtual base class for polymorphic message classes. all messages have a session-d attribute Ys are instances of classes derived from a virtual message hanler base class. foo() is the message handler function. Z is the 'message pump' that dispatches messages to Ys based upon the session-id. Y instances insert make_pair(session-id, message_handler) pairs into the map. (I think _1 is 'this' during the insert.) Z calls the Y instance message-handler using the session-id key to the map. </context> Mark Storer <mstorer@cardiff To: "'Boost-Users(a)yahoogroups.com'" <Boost-Users(a)yahoogroups.com> .com> cc: Subject: RE: [Boost-Users] bind: I just keep trying... 09/25/2002 04:47 PM Please respond to Boost-Users I'm a little confused as to what you're aiming for here... a map of ints to function pointers (that can point to Y::foo)? This should do the trick, provided I'm recalling my function pointer declarations correctly std::map<int, short()(*X)> Further boost::bind creates an INSTANCE of a functor. Giving the compiler an instance when it wants a type is not a good way to keep it happy. Now if what you're actually after is calling Y::foo on a colleciton of Y's, then you don't need a collection of function pointers for each instance in the first place, which is where bind comes in. According to my flimsy understanding of bind (I haven't used it yet), this should do the trick: X someX; std::vector<Y> &wise = BuildYs(); // wise == plural of Y std::for_each( wise.begin(), wise.end(), boost::bind<short>(&Y::foo, &someX) ); If you want the X parameter to vary from one call of foo to the next, I suggest rolling your own loop... or incorporating the X* into Y, at which point you can get rid of the X* parameter, and use boost::bind(&Y::foo), or std::mem_fun(&Y::foo). --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] Sent: Wednesday, September 25, 2002 4:08 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] bind: I just keep trying... Everytime I think I have a clue, I'm reminded how little I REALLY understand. <error compiler='VC6SP4'> 'map' : invalid template argument for '_Ty', type expected </error> <snippet> struct X { } struct Y { short foo(X*); } struct Z { map<int, bind(&Y::foo, _1, _2) > myMap; } </snippet> I thought I saw how to do this somewhere on the website but I sure can't find it now. Any help GREATFULLY appreciated. Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

1 0

std::swap() vs boost::swap()
by Galante Michele 26 Sep '02

26 Sep '02

Boost classes that define a swap() member function usually also provide a global swap() function: namespace boost { class X { void swap(X &rhs); }; template<class T> void swap(X &lhs, X &rhs) { lhs.swap(rhs); } } Why is the global swap() function defined in namespace boost and not as a specialization of std::swap<>() in namespace std? Suppose I have a template function like the following: #include <algorithms> template <typename T> void do_something_and_swap(T &a, T &b) { // do something ... std::swap(a, b); } I want this template function to work with every type that is "swappable", but if I try to use it with boost::scoped_ptr<> the compiler fails because std::swap<>() is not specilized for boost::scoped_ptr<> and the generic definition of std::swap<>() requires the argument type to be copyable (and boost::scoped_ptr<> is noncopyable). I think I have read somewhere (but perhaps I'm wrong) that specialization of std::swap<>() for user defined types is allowed by the standard, so is there any other reason for not defining the global swap functions in namespace std? Michele Galante Zucchetti Centro Sistemi s.p.a. m.galante(a)centrosistemi.it

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RE: [Boost-Users] std::swap() vs boost::swap()
by scleary＠jerviswebb.com 26 Sep '02

26 Sep '02

> From: Galante Michele [mailto:M.Galante@centrosistemi.it] > > Suppose I have a template function like the following: > > #include <algorithms> > > template <typename T> > void do_something_and_swap(T &a, T &b) > { > // do something ... > std::swap(a, b); > } > > I want this template function to work with every type that is "swappable", > but if I try to use it with boost::scoped_ptr<> the compiler fails because > std::swap<>() is not specilized for boost::scoped_ptr<> and the generic > definition of std::swap<>() requires the argument type to be copyable (and > boost::scoped_ptr<> is noncopyable). The best way to provide this solution is to use an unqualified swap; Koenig lookup will ensure that the correct swap() is found for std:: and boost:: components. > I think I have read somewhere (but perhaps I'm wrong) that specialization of > std::swap<>() for user defined types is allowed by the standard, so is there > any other reason for not defining the global swap functions in namespace > std? Technically, specialization of std::swap is allowed. But overloading std::swap is not. These are often confused, but here's a concrete example: template <> void std::swap(boost::scoped_ptr<int> &, boost::scoped_ptr<int> &) is a specialization, and legal; but: template <typename T> void std::swap(boost::scoped_ptr<T> &, boost::scoped_ptr<T> &) is an overload, and not legal (currently). There's been a ton of discussion of this issue on the Boost.Developer's list; you can search the list archives if you're interested. -Steve

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Forte compiler template error
by Tanmay Patwardhan 26 Sep '02

26 Sep '02

Hi, I was trying to use the tokeniser lib and encountered this error: "/home/patwarta/boost_1_28_0/boost/iterator_adaptors.hpp", line 819: Error: The base "boost::detail::iterator_adaptor_traits_gen<boost::detail::token_ iterator_base<const char*>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>*, std::forward_iterator_tag, int>::type" must be a previously defined class or struct. "XMLbParserWrapper.cxx", line 11: Where: While specializing "boost::iterator_adaptor<boost::detail::token_iterator_ba se<const char*>, boost::detail::tokenizer_policy<std::basic_string<char, std::char_traits<char>, std::allocator<char>>, boost::char_delimiters_separator<char, std::char_traits<char>>>, std::basic_string<char, std::char_traits<char>, std::allocator<char>>, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>&, const std::basic_string<char, std::char_traits<char>, std::allocator<char>>*, std::forward_iterator_tag, int> Any ideas? Thanks in advance, Tanmay

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RE: [Boost-Users] bind: I just keep trying...
by Mark Storer 25 Sep '02

25 Sep '02

I'm a little confused as to what you're aiming for here... a map of ints to function pointers (that can point to Y::foo)? This should do the trick, provided I'm recalling my function pointer declarations correctly std::map<int, short()(*X)> Further boost::bind creates an INSTANCE of a functor. Giving the compiler an instance when it wants a type is not a good way to keep it happy. Now if what you're actually after is calling Y::foo on a colleciton of Y's, then you don't need a collection of function pointers for each instance in the first place, which is where bind comes in. According to my flimsy understanding of bind (I haven't used it yet), this should do the trick: X someX; std::vector<Y> &wise = BuildYs(); // wise == plural of Y std::for_each( wise.begin(), wise.end(), boost::bind<short>(&Y::foo, &someX) ); If you want the X parameter to vary from one call of foo to the next, I suggest rolling your own loop... or incorporating the X* into Y, at which point you can get rid of the X* parameter, and use boost::bind(&Y::foo), or std::mem_fun(&Y::foo). --Mark Storer Software Engineer Cardiff Software #include <disclaimer> typedef std::disclaimer<Cardiff> Discard; -----Original Message----- From: dick.bridges(a)tais.com [mailto:dick.bridges@tais.com] Sent: Wednesday, September 25, 2002 4:08 PM To: boost-users(a)yahoogroups.com Subject: [Boost-Users] bind: I just keep trying... Everytime I think I have a clue, I'm reminded how little I REALLY understand. <error compiler='VC6SP4'> 'map' : invalid template argument for '_Ty', type expected </error> <snippet> struct X { } struct Y { short foo(X*); } struct Z { map<int, bind(&Y::foo, _1, _2) > myMap; } </snippet> I thought I saw how to do this somewhere on the website but I sure can't find it now. Any help GREATFULLY appreciated. Info: <http://www.boost.org> Wiki: <http://www.crystalclearsoftware.com/cgi-bin/boost_wiki/wiki.pl> Unsubscribe: <mailto:boost-users-unsubscribe@yahoogroups.com> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/

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