These three parameters:
are always passed to Field_xxx constructor.
Under terms of MDEV-4912 we'll introduce a few methods in Type_handler which will do "new Field_xxx". Before doing this, to make the Type_handler API look simpler, we'll introduce a new class:
- Derive Field from Record_addr
- Change Field constructors to accept a "const Record_addr &addr" parameter instead of the three separate parameters ptr_arg, null_ptr_arg, null_bit_arg.