Re: [Boost-users] Insertion/Use of boost::multi_index

Hi Joaquin, This is the exact error I am facing, When I insert like "sample.insert(&a);", I get errors like, . . . kytj.cpp ky_op_tj.cpp c:\code\common\lib\boost\boost\multi_index\hashed_index.hpp(1155) : error C2064: term does not evaluate to a function taking 2 arguments class does not define an 'operator()' or a user defined conversion operator to a pointer-to-function or reference-to-function that takes appropriate number of arguments c:\code\common\lib\\boost\boost\multi_index\hashed_index.hpp(1152) : while compiling class template member function 'bool boost::multi_index::detail::hashed_index::link_point(Container *const ,boost::multi_index::detail::hashed_index_base_node_impl<Allocator> *&,boost::multi_index::detail::hashed_unique_tag)' with [ KeyFromValue=boost::multi_index::const_mem_fun, Hash=boost::multi_index::const_mem_fun, Pred=boost::multi_index::const_mem_fun, SuperMeta=boost::multi_index::detail::nth_layer<1,Container *,boost::multi_index::indexed_by,boost::multi_index::const_mem_fun< DBObject,Vs64,DBObject::getKey2>,boost::multi_index::const_mem_fun>>,std::allocator>, TagList=boost::mpl::vector0boost::mpl::na, Category=boost::multi_index::detail::hashed_unique_tag, Allocator=std::allocator<char> ] c:\code\common\lib\boost\boost\multi_index_container.hpp(100) : see reference to class template instantiation 'boost::multi_index::detail:: hashed_index' being compiled with [ KeyFromValue=boost::multi_index::const_mem_fun, Hash=boost::multi_index::const_mem_fun, Pred=boost::multi_index::const_mem_fun, SuperMeta=boost::multi_index::detail::nth_layer<1,Container *,boost::multi_index::indexed_by,boost::multi_index::const_mem_fun< DBObject,Vs64,DBObject::getKey2>,boost::multi_index::const_mem_fun>>,std::allocator>, TagList=boost::mpl::vector0boost::mpl::na, Category=boost::multi_index::detail::hashed_unique_tag ] c:\code\common\src\biz\model\stm-stow_model\stm_container_manager_abc.h(300) : see reference to class template instantiation 'boost::multi_index::multi_ index_container' being compiled with [ Value=Container *, IndexSpecifierList=boost::multi_index::indexed_by,boost::multi_index:: const_mem_fun,boost:: multi_index::const_mem_fun>> ] xtyz.cpp . . . Build log was saved at "file://c:\code\win\Debug\obj\BuildLog.htm" ProjABC - 1 error(s), 0 warning(s) ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== Thanks, Ram On Mon, Sep 19, 2016 at 12:59 PM, Joaquin M López Muñoz < joaquinlopezmunoz@gmail.com> wrote:

El 19/09/2016 a las 7:54, Ram escribió:

Hi All ,

I have created a boost::multi_index container for my use and it compiles successfully. [...] The container I defined is ,

typedef boost::multi_index_ClassX< ClassX*, boost::multi_index::indexed_by< boost::multi_index::hashed_unique< boost::multi_index::const_mem_fun, boost::multi_index::const_mem_fun,

...

MultiIndexedClassX;

I'm afraid this is seriously wrong (leaving aside the translation typos such as "boost::multi_index_ClassX" instead of "boost::multi_index_container" etc.) The structure of a definition of a multi_index_container is

multi_index_container< element_type, indexed_by< index_specifier1<index1 args>, index_specifier2<index2 args>, ... >

...

where each index_specifier is one of "hashed_unique", "hashed_non_unique", "ordered_unique", etc. I assume your intention is to have *two* hashed indices (by key1 and key2, respectively), so rather than

indexed_by< hashed_unique

...

(which is what you've written), the definition has to follow this structure:

indexed_by< hashed_unique, hashed_unique

...

See the difference? Your original definition is just plain wrong, and the fact that it seems to compile is sheer luck (or lack of it): once you start trying to use it, compile-time errors will pop up. (if you're curious, Boost.MultiIndex is trying to use your second const_mem_fun as a hash function of the first const_mem_fun, which, of course, makes no sense, but this is what you instructed the lib to do).

I've written a small test program reproducing your scenario that you can play with at

http://coliru.stacked-crooked.com/a/456f8546e51a29e6

Note that, here, sample.insert(&a) works without problems.

Joaquín M López Muñoz

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