Changing public instance attribute

Question

Hi all,
i'm a newbie in programming OO. So i have a little Problem with my Coding.
i have to change a value vom a structure. It an public instance attribute from the superclass. So how can i change it?
coding it like this:
go_busobj_created-ms_detail-nr = '1020'.
shows an error that go_busobj_created ist an objectreferenz and does'n own a component "ms_detail-snunr" - But in debugging i can navigate with doubleclick into ms_detail and ich can change manually thy value.
The other way i tried is using the method from a superclass that my object (go_busobj_created) inherits during runtime. But i don't know how to call it.
call METHOD CL_SUPERCLASS=>('SET_NR')
or
call METHOD ('IF_SUPERCLASS~SET_NR')
I can call static or dynamic - everytime it dumps..
Thanks for your help.
Stefan

Answer 1

Hello Stefan
Based on my knowledge from RE-FX I assume that GO_BUSOBJ is a very generic object reference. Thus, in order to access the instance attribute MS_DETAIL you have to do a narrowing cast:
DATA:
  go_busobj       TYPE REF TO <generic class>,
  go_specific      TYPE REF TO <specific class which is a subclass of generic class>.
  go_specific ?= go_busobj.  " narrowing cast
  go_specific_created->ms_detail-nr = '1020'.
For example, the BDT function modules in RE-FX pass most (if not all) object references as TYPE REF TO cl_reca_storable. The actual object may be a contract (CL_RECN_CONTRACT), a building (CL_REBD_BUILDING) or some other RE object.
Regards
  Uwe