using a generic object

[Former Member]

I would like to be able to create an instance of an ABAP object without knowing the object type first. for example, if a specific type of message hits a queue, create a handler object specific to that message. I need to be able to declare the object variable as something not strongly typed, and do the create object for whatever actual object i want to use. I have checked the docs, but found nothing.

[Former Member]

Hello David,

If I have understood your requirement correctly, then I think it is possible to meet it. Consider the following example :

data w_obj type ref to object.
data meth(5) type c value 'WRITE'.

class test definition.
  public section.
    data:
      lv_test_variable type c value 'A'.
    methods write.
endclass.

class test implementation.
  method write.
    write:
        lv_test_variable,
        'Simple Sample'.
  endmethod.
endclass.

start-of-selection.

create object w_obj type test.

call method w_obj->(meth).

As you are sure to discover, this approach has some limitations. I have not studied this thoroughly, but at least you can begin thinking in the lines of creating Object References.

I hope this has been of some help to you.

Regards,

Anand Mandalika.

[Former Member]

Hi,

Take a look at the document https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/com.sap.km.cm.docs/documents/a1-8-4/advanced and generic programming in abap.pdf and the webcast titled <b>Advanced and Generic Programming in ABAP</b> in the SAP TechEd Education Sessions available on SDN. It will help you in getting an idea about runtime type specification. The book Abap Objects gives a detailed description of the concepts as well.

If your prgram is using inheritance/interfaces, you can use polymorphism to achieve your purpose. Otherwise, take a look at the documentation for <b>CREATE DATA dref TYPE REF TO type|(typename)</b> and cl_abap_refdesc=>create_by_name( 'CLASS_NAME' )

Hope this helps.

Regards

Message was edited by: Shehryar Khan

[Former Member]

Hi David,

I think this feature can be achieved only in WAS 6.40. ( Someone correct me here, if I am wrong ).

This syntax is available, perhaps only in 6.40 WAS, and didn't work in 4.6C.

CREATE DATA dref TYPE HANDLE <class_name>.

Since, I do not have 6.40 WAS, I will give a shot-in-the-dark solution:

data: lv_variable(25) type c value 'CL_GUI_ALV_GRID'.
data: myref type ref to data.

field-symbols: <FS> type any.

assign lv_variable to <fs>.
if sy-subrc = 0.
  create data myref type handle <fs>.
endif.

I do not guarantee this will work, but with the document link, which Shehryar Khan has given in the previous post, I am guessing this should work.

If it works, then you can create an object at runtime, of any classname.

Regards,

Subramanian V.

[Former Member]

Hi,

The statements <b>DATA <dref> TYPE REF TO DATA</b> and <b>CREATE DATA <dref> TYPE <type>|LIKE <obj></b> are available since ver 4.6. So creating a data/object reference dynamically and calling its methods should not be an issue even in versions earlier than 6.40. The HANDLE addition perhaps requires a newer version.

Regards

[Former Member]

Thanks Shehryar. I was aware of that. I was only concerned about the 'HANDLE' clause.

Regards,

Subramanian V.