## Set the identifier creator handler

Identifiers are created in some parsers by generating them automatically or via hints given a syntax. Raptor can customise this process using a user-supplied identifier handler function. For example, in RDF/XML generated blank node identifiers and those those specified `rdf:nodeID` are passed through this process. Setting a handler allows the identifier generation mechanism to be fully replaced. A lighter alternative is to use `raptor_world_set_generate_bnodeid_parameters()` to adjust the default algorithm for generated identifiers.

It is used as follows

      raptor_generate_bnodeid_handler bnodeid_handler;

      raptor_world_set_generate_bnodeid_handler(rdf_parser, user_data, bnodeid_handler);

The bnodeid_handler takes the following signature:

    unsigned char*
    generate_id_handler(void* user_data, unsigned char* user_id)
    {
       /* return a new generated ID based on user_id (optional) */
    }

where user_id an optional user-supplied identifier, such as the value of a `rdf:nodeID` in RDF/XML.