[boost] [multi_index] Question about 'modify'

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-08-30 08:26:20

I have a question about the 'modify' method of ordered indexes in the 
multi_index library. I have an iterator obtained from an ordered index and 
would like to modify the pointed element. I'm pretty sure that the 
modification won't change the order, won't create collisions and so on.

The documentation suggests to use either 'replace', or more efficient 'modify' 
method. Why can't I do the following:

     typedef variables_t::nth_index<1>::type index_t;
     index_t& index = variable_declarations.get<1>();
     index_t::iterator existing = index.find(vd);
     const_cast<Variable_declaration&>(*existing)
                        .make_external();

? 

TIA,
Volodya