Re: [Boost-users] Boost.MultiIndex. Using several keys together.

Subject: Re: [Boost-users] Boost.MultiIndex. Using several keys together.
From: Jason Roehm (jasonr_at_[hidden])
Date: 2014-02-05 08:12:35

On 02/04/2014 04:35 PM, syvyi wrote:
> What if the composite key should be parameterized from a file?
>
> In the case of
> <raw>
> struct  phonebook_entry
> {
>    std::string  family_name;
>    std::string  given_name;
>    std::string  phone_number;
>
>    phonebook_entry(
>      std::string  family_name,
>      std::string  given_name,
>      std::string  phone_number):
>      family_name(family_name),given_name(given_name),phone_number(phone_number)
>    {}
> };
>
> // define a multi_index_container with a composite key on
> // (family_name,given_name)
> typedef  multi_index_container<
>    phonebook_entry,
>    indexed_by<
>      //non-unique as some subscribers might have more than one number
>      ordered_non_unique<  
>        composite_key<
>          phonebook_entry,
>          member<phonebook_entry,std::string,&phonebook_entry::family_name>,
>          member<phonebook_entry,std::string,&phonebook_entry::given_name>
>        >
>      >,
>      ordered_unique<  // unique as numbers belong to only one subscriber
>        member<phonebook_entry,std::string,&phonebook_entry::phone_number>
>      >
>    >
> >  phonebook;
> </raw>
>
> the lines
>          member<phonebook_entry,std::string,&phonebook_entry::family_name>,
>          member<phonebook_entry,std::string,&phonebook_entry::given_name>
> should be auto-generated by reading a composite key from a file.

That use case sounds incompatible with composite keys, which must be 
defined at compile time. In that case, I would recommend creating 
individual indices on the container for each field that you might want 
to use at runtime, but you would lose the composite key functionality.

Jason