OOP for abap

Question

good morning to all sap experts,
i have a question for any OOP programmers in abap. i have been working in abap for over 12 years, but have not yet transitioned to oop. but, since we have been upgrading to ecc 6.0, i am constantly working with oop classes, and objects. maybe someone can answer these questions, and also point me in the right direction online, to educate myself.
i have a class that is called CL_WTY_CLAIM and it is running a method called get_direct_references. within get_direct_references, this line of code is running.
co_ltext ?= co_ext_objects->get_ext_buffered_object(
                                  co_ltext_class_id ).
firstly, what does "?=" mean?
secondly, if i go to get_ext_buffered_object, i find the following code.
ro_object = co_ext_objects->get_ext_buffered_object( io_id ).
how/where is the code running to fill the initial co_ltext field?
please and thank you.

Answer 1

thanks for the quick reply. i think i understand the down cast function.
when i debug the code at the point of the following:
co_ltext ?= co_ext_objects->get_ext_buffered_object(
                                  co_ltext_class_id ).
it goes to the get_ext_buffered_object method, and i see the following:
data:
    ls_ext_object type t_ext_object.
  read table ct_external_objects into ls_ext_object
    with table key id = io_id.
  ro_object = ls_ext_object-object.
can you easily tell me how the ct_external_objects table is populated? i know that the table is in another class "CL_WTY_BUFFER_EXT_CNTL" and it is a attribute of that class, but i do not know how it is populated. do you have another link to show me a easy way to determine how a table is populated?
the issue i am having is that this table does not always have the text info i am looking for. i would like to review their code to see if it is a data problem, or a code problem.
thanks again.