Hi, How can I read in a from a stream when I don't know the exact type I will be getting? All objects I receive will derive from the same base class, but I won't know when I receive the stream what the derived type will be and therefore I can't create it in advance (like in the docs). class base { ... } class derived1 : public base { ... } class derived2 : public base { ... } int main() { // Get a stream from somewhere boost::archive::binary_iarchive ia( instream ); base b0; derived1 d1; derived2 d2; is >> // derived1 or derived2??? } Ryan Fowler Software Engineer Thomson Reuters Phone: +442075427063 ryan.fowler@thomsonreuters.com thomsonreuters.com This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters.
This is explained in the documentation and illustrated by the demos and tests. In fact, you can even build a progam which will be able to de-serialize types included in DLLS which have yet to be created. Robert Ramey "Ryan Fowler" <Ryan.Fowler@thomsonreuters.com> wrote in message news:1C50BA0DCB34A24E9C8ABA96570EF18F073F5211@LONSMSXM06.emea.ime.reuters.com... Hi, How can I read in a from a stream when I don't know the exact type I will be getting? All objects I receive will derive from the same base class, but I won't know when I receive the stream what the derived type will be and therefore I can't create it in advance (like in the docs). class base { . } class derived1 : public base { . } class derived2 : public base { . } int main() { // Get a stream from somewhere boost::archive::binary_iarchive ia( instream ); base b0; derived1 d1; derived2 d2; is >> // derived1 or derived2??? } Ryan Fowler Software Engineer Thomson Reuters Phone: +442075427063 ryan.fowler@thomsonreuters.com thomsonreuters.com This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters. ------------------------------------------------------------------------------ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
I've seen the following: main(){ ... base *b; ... ar & b; } But that doesn't quite help me. All of our objects come from a memory pool and I either need to know ahead of time which object to allocate or I need to pass an allocator to the archive so that it can get the memory from the pool. Are either of these possible? Also, in the above example, how does the archive allocate the memory for 'b'? Does it use new? Or does it have it's own pre-allocated store? Thanks, Ryan From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey Sent: 04 March 2009 17:30 To: boost-users@lists.boost.org Subject: Re: [Boost-users] [Serialization] Load an object from the base pointer This is explained in the documentation and illustrated by the demos and tests. In fact, you can even build a progam which will be able to de-serialize types included in DLLS which have yet to be created. Robert Ramey "Ryan Fowler" <Ryan.Fowler@thomsonreuters.com> wrote in message news:1C50BA0DCB34A24E9C8ABA96570EF18F073F5211@LONSMSXM06.emea.ime.reuter s.com... Hi, How can I read in a from a stream when I don't know the exact type I will be getting? All objects I receive will derive from the same base class, but I won't know when I receive the stream what the derived type will be and therefore I can't create it in advance (like in the docs). class base { ... } class derived1 : public base { ... } class derived2 : public base { ... } int main() { // Get a stream from somewhere boost::archive::binary_iarchive ia( instream ); base b0; derived1 d1; derived2 d2; is >> // derived1 or derived2??? } Ryan Fowler Software Engineer Thomson Reuters Phone: +442075427063 ryan.fowler@thomsonreuters.com thomsonreuters.com This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters. ________________________________ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters.
This is all done internally by the library. Feel free to browse through the source and documentation. Robert Ramey "Ryan Fowler" <Ryan.Fowler@thomsonreuters.com> wrote in message news:1C50BA0DCB34A24E9C8ABA96570EF18F073F5212@LONSMSXM06.emea.ime.reuters.com... I've seen the following: main(){ ... base *b; ... ar & b; } But that doesn't quite help me. All of our objects come from a memory pool and I either need to know ahead of time which object to allocate or I need to pass an allocator to the archive so that it can get the memory from the pool. Are either of these possible? Also, in the above example, how does the archive allocate the memory for 'b'? Does it use new? Or does it have it's own pre-allocated store? Thanks, Ryan From: boost-users-bounces@lists.boost.org [mailto:boost-users-bounces@lists.boost.org] On Behalf Of Robert Ramey Sent: 04 March 2009 17:30 To: boost-users@lists.boost.org Subject: Re: [Boost-users] [Serialization] Load an object from the base pointer This is explained in the documentation and illustrated by the demos and tests. In fact, you can even build a progam which will be able to de-serialize types included in DLLS which have yet to be created. Robert Ramey "Ryan Fowler" <Ryan.Fowler@thomsonreuters.com> wrote in message news:1C50BA0DCB34A24E9C8ABA96570EF18F073F5211@LONSMSXM06.emea.ime.reuters.com... Hi, How can I read in a from a stream when I don't know the exact type I will be getting? All objects I receive will derive from the same base class, but I won't know when I receive the stream what the derived type will be and therefore I can't create it in advance (like in the docs). class base { . } class derived1 : public base { . } class derived2 : public base { . } int main() { // Get a stream from somewhere boost::archive::binary_iarchive ia( instream ); base b0; derived1 d1; derived2 d2; is >> // derived1 or derived2??? } Ryan Fowler Software Engineer Thomson Reuters Phone: +442075427063 ryan.fowler@thomsonreuters.com thomsonreuters.com This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters. ---------------------------------------------------------------------------- _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users This email was sent to you by Thomson Reuters, the global news and information company. Any views expressed in this message are those of the individual sender, except where the sender specifically states them to be the views of Thomson Reuters. ------------------------------------------------------------------------------ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users
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