Re: [Boost-users] [multi_index] illegal indirection compile error

Thanks for the reply. I will use the workaround for the time being until the new boost release comes up. JOAQUIN LOPEZ MU?Z wrote:

----- Mensaje original ----- De: Themistoklis Bourdenas Fecha: Lunes, Julio 31, 2006 4:47 pm Asunto: [Boost-users] [multi_index] illegal indirection compile error

...

Could you help me understand what I'm doing wrong in the code below? I'm trying to setup a multi_index structure of class B.

class A { const std::string& ID(void) const; ... };

class B : public A { ... };

typedef boost::multi_index::multi_index_container< B*, boost::multi_index::indexed_by< boost::multi_index::ordered_unique< boost::multi_index::const_mem_fun >

...

BSet;

However when I compile VS2005 returns me an "illegal indirection" compile error. Any thoughts?

Hello Themistoklis,

You've found a limitation in Boost.MultiIndex (as of Boost 1.33.1) by which one cannot specifiy a key in a given base class and pass derived classes as elements. This is solved in what will become Boost 1.34, please read bullet 3 of Boost.MultiIndex release notes at:

http://boost- consulting.com/boost/libs/multi_index/doc/release_notes.html#boost_1_34

Until this release is out, you can use the following workarond: simply define a custom key extractor like this (warning, I haven't compiled it, beware typos):

struct pB_ID_extractor { typedef std::string result_type; const std::string& operator()(const B* pb)const { return pb->ID(); } };

typedef boost::multi_index::multi_index_container< B*, boost::multi_index::indexed_by< boost::multi_index::ordered_unique< pB_ID_extractor >

...

BSet;

Does this help? Thank you for using Boost.MultiIndex,

Joaquín M López Muñoz Telefónica, Investigación y Desarrollo