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is somewhat archaic - I'm not using RTTI or exceptions (the compiler >>> supports them but it is currently broken) - the STL has

support RTTI (exceptions are fine). This is annoying because the > debuggers for these embedded devices are sometimes flaky and logging on > device is sometimes the only way to fix bugs. So we have to have another > simple homegrown logging library for on device logging. > > There are many other Boost libraries that we can't use, at least out of > the box, because they use RTTI in one or two

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I would use it as a lightweight and more convenient replacement for >> boost::shared_ptr<const T>. >> >> In my application I might have < 50 objects that needs to by flyweights. >> They are almost never identical, and if they are, the memory occupied by >> the factory would probably be much larger than that of duplication. > > Well, then you might not need using the flyweight idiom > after all... Well, it's lower overhead (if no factory and forwarding constructors/operations makes it a better choice than shared_ptrconst T>. -Thorsten Thorsten Ottosen: > Joaquin M Lopez Munoz skrev: >> Thorsten Ottosen <thorsten.ottosen <at> dezide.com> writes: > >>> I would use it as a lightweight and more convenient replacement for >>> boost::shared_ptr<const T>. >>> >>> In my application I might have < 50 objects that needs to by flyweights.

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They are almost never identical, and if they are, the memory occupied by >>> the factory would probably be much larger than that of duplication. >> >> Well, then you might not need using the flyweight idiom >> after all... > > Well, it's lower overhead (if no factory and forwarding > constructors/operations makes it a better choice than shared_ptrconst T>. It might be possible to do this using a custom factory along the lines of: template<class T> struct sp_factory { typedef boost::shared_ptr<T const> handle_type; handle_type insert( T const & t ) { return handle_type( new T( t ) ); } void erase( handle_type ) {} T const & entry( handle_type p ) { return *p; } }; but there's no way to tell from the documentation; it never describes how the Factory template parameter is actually used. http://svn.boost.org/svn/boost/ sandbox/flyweight/libs/flyweight/ doc/reference/flyweight.html#fly weight As I read it, a flyweight<> can ignore all of its template

I've posted a modification to enable_shared_from_this() to support calling shared_from_this in a constructor and destructor. d Any feedback? Abrahams) 16. Re: Trac open bug summary mailings missing new tickets (Rene Rivera) 17. BoostCon 2008: May 4-9 (David Abrahams) 18. Re: Reporting bugs at Trac? (Olaf van der Spek) 19. Re: [serialization] serialization used in multiple DLL problems (Felipe Magno de Almeida) 20. [review] Formal Fast-Track review of the Boost.Functional/Factory library begins today (John Torjo) Michael Marcin wrote: > John Torjo wrote: >> Eames, Andrew wrote: >>> Hi, >>> >>> I apologize if this is a FAQ - I couldn't find much on other compilers >>> >>> >>> >>> I am interested in using boost with a compiler for a DSP - The compiler old iostreams >>> and no doubt I will find some other musty corners. I don't have any >>> illusions about getting the whole of boost to compile but I'm sure there >>> are some large pieces that will work OK. I have no problem doing the >>> port myself. >>> >>> >>> >> RTTI is pretty useful, and I think quite a few libraries rely on >> dynamic_cast at least once. >> >> For instance Boost Logging Lib ( http://torjo.com/log2/) relies on it >> once - I guess you could get 'round it. >> >> I guess the 1M$ question is : why do you need that specific compiler? >> > > I'm in a similar situation where I have to use a specific compiler > because it's the only compiler supported by the closed SDK for the > platform we're developing for. > > Right now I, unfortunately, can only use the Torjo logging library for a > windows port of the application because the target platform doesn't places where they probably > don't have to. For instance lexical_cast uses it to provide extra > information to the bad_lexical_cast exception but functions just fine > without it. I didn't dig enough into the implementation but it looks > like Boost.Function and Boost.Variant may be in a similar boat. > > I think shared_ptr used to have this issue but got changed after 1.34. I > wish more libraries would follow its lead if possible. You can raise the viability of the issue by submitting patches. Where RTTI is useful, but not essential, I'd personally rather not remove it entirely. Instead, the code could respond to a macro (BOOST_NO_RTTI perhaps) and avoid usage when present. But the default would be to user RTTI on the theory it is usually available. --Beman Beman Dawes: > Where RTTI is useful, but not essential, I'd personally rather not > remove it entirely. Instead, the code could respond to a macro > (BOOST_NO_RTTI perhaps) and avoid usage when present. In non-essential scenarios, often the proper macro to test is BOOST_NO_TYPEID: http://svn.boost.org/trac/boost/ ticket/1104 since typeid(T) does not require the R in RTTI and may be supported even when RTTI is off (under MSVC for example). Joaquin M Lopez Munoz skrev: > Thorsten Ottosen <thorsten.ottosen <at> dezide.com> writes: parameters beyond T and still conform to its spec, which is probably not what's intended. Peter Dimov wrote: > Beman Dawes: > >> Where RTTI is useful, but not essential, I'd personally rather not >> remove it entirely. Instead, the code could respond to a macro >> (BOOST_NO_RTTI perhaps) and avoid usage when present. > > In non-essential scenarios, often the proper macro to test is > BOOST_NO_TYPEID: > > http://svn.boost.org/trac/boost/ ticket/1104 > > since typeid(T) does not require the R in RTTI and may be supported even > when RTTI is off (under MSVC for example). Good point. --Beman There's a file called 'madshell.phtml' in the Vault that is probably an exploit. I see a few other .phtml's as well. -- Peter Dimov http://www.pdimov.com >>> So you can call it whatever you like and still be right :-) >>> >>> BTW I believe the min and max cases are basically just mirror >>> images of each >>> other about the location parameter? >> >> So names aside, it's all the extreme value distribution, but there >> are minimum and maximum variations of it. I found this... It was a nice overview of some of the distribution. Section 1.2 has a nice overview of the type 1, 2 and 3 distributions and how they relate (and how they're related to Weibull, for example). I wonder if I can find this book in our math library... http://www.worldscibooks.com/ mathematics/p191.html Andrew Sutton asutton@cs.kent.edu Peter Dimov wrote: > There's a file called 'madshell.phtml' in the Vault that is probably an > exploit. I see a few other .phtml's as well. Thanks for pointing those out. I've adjusted the cleanup filter accordingly. -- -- Grafik - Don't Assume Anything -- Redshift Software, Inc. - http://redshift-software.com -- rrivera/acm.org - grafik/redshift-software.com -- 102708583/icq - grafikrobot/aim - grafikrobot/yahoo More about http://svn.boost.org/svn/boost/ sandbox/flyweight/libs/flyweight/ doc/reference/flyweight.html#fly weight I don't understand the source of the complexity at the flyweight<> level. A "naive" flyweight<> could look like: template<class T, class F = default_factory> class flyweight { typedef typename F::handle_type handle_type; handle_type handle_; public: flyweight( ... args ): handle_( F::insert( T( args... ) ) ) {} T const& get() const { return F::value( handle_ ); } }; It seems to me that this provides the same amount of expressive power as the current interface. Locking/tracking/holding can be made parameters of the Factory if so desired, and a factory_core<F',L,T,H> template may be provided as a convenience in a separate header, but in the majority of the cases the user will never need it. In fact flyweight<> is already implemented in a similar way, it uses a flyweight_core<> class as F. Note that the above simpler flyweight<> allows me to pass the aforementioned template<class T> struct sp_factory { typedef boost::shared_ptr<T const> handle_type; static handle_type insert( T const & t ) { return handle_type( new T( t ) ); } static T const & entry( handle_type p ) { return *p; } }; as F; there's no need to invent a locking policy, a tracking policy, a holder, or a stateful factory. ----- Mensaje original ----- De: Peter Dimov <pdimov@pdimov.com> Fecha: Domingo, Diciembre 16, 2007 8:27 pm Asunto: Re: [boost] [flyweight] some minor comments Para: boost@lists.boost.org > Thorsten Ottosen: > > Well, it's lower overhead (if no factory and forwarding > > constructors/operations makes it a better choice than > shared_ptrconst T>. > > It might be possible to do this using a custom factory along the > lines of: > > template<class T> struct sp_factory > { > typedef boost::shared_ptr<T const> handle_type; > > handle_type insert( T const & t ) { > return handle_type( new T( t ) ); } > void erase( handle_type ) {} > T const & entry( handle_type p ) { return *p; } > }; This approach would work (except for a technical issue I comment later) but it's overkill because it provides its own tracking, which is already taken care of by the Tracking policy. One would use then in conjunction with the no_tracking and no_locking policies, sort of like this: template<class T> using no_factory_flyweight= flyweight<T,sp_factory<_1,_2>,n o_tracking,no_locking>; An alternative would be to provide an even simpler factory: template<typename Entry,typename Value> struct trivial_factory { typedef const Entry* handle_type; handle_type insert(const Entry& x){return new Entry(x);} void erase(handle_type p){delete p;} const Entry& entry(handle_type p){delete p;} }; // default tracking is ref_counted template<class T> using no_factory_flyweight= flyweight<T,trivial_factory<_1,_2 >,no_locking>; Either of these two alternatives *almost* works, but for a detail: equality of flyweight objects is defined in terms of equality of reference, i.e. x==y iff &x.get()==&y.get(). sp_factory (and trivial_factory) interpret every value as distinct for any other: no_factory_flyweight<std:string> x("hello"), y("hello"); assert(x!=y); //assertion passes which results in no value sharing, except when a flyweight is copied from another. Nothing wrong with this as long as it is known and accepted, of course. > bu ... This message is too long, the rest is truncated. On 12/17/07, boost-request@lists.boost.org <boost-request@lists.boost.org> wrote:

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