topic Re: Class parameters not seen in all methods in Application Development and Automation Discussions

Class parameters not seen in all methods

Former Member — Mon, 16 Apr 2007 15:40:49 GMT

Dear experts,

Please help!

I have two classes in my program:

Class "screen_init" and class "screen_handler".

Each class has its own constructor plus other methods.

For example class "screen_handler" has methods "constructor", "handle_node_double_click",

"handle_picture_double_click", "handle_textedit_double_click".

In Constructor of class "screen_init" I do:

- define event_handler:

 Data  event_handler type ref to screen_handler

- create an object event_handler:

        Create object  event_handler
           exporting textedit = textedit
                      tree = tree.

In definition section of class "screen_handler" I define constructor as:

   methods: constructor importing
                  textedit type ref to cl_gui_textedit
                  tree type ref to cl_gui_simple_tree.

When the program creates an object event_handler - then the Constructor of class "screen_handler" is run.

The problem is that textedit and tree are successfully received in the Constructor of "screen_handler" class. But when it gets to any other method of "screen_handler" class ( method "handle_textedit_double_click", for example) - these objects are empty.

I need tree object when method "handle_textedit_double_click" is run - so I could read textedit and then repopulate the tree depending on textedit value.

Please note that textedit and tree are defined in both classes in Public section:

class screen_init definition.
public section.
    data: textedit type ref to CL_GUI_TEXTEDIT,
            tree type ref to cl_gui_simple_tree.
class screen_handler definition.
  public section.
 data: textedit type ref to CL_GUI_TEXTEDIT,
          tree type ref to cl_gui_simple_tree

Thank you,

Tatyana.

Re: Class parameters not seen in all methods

uwe_schieferstein — Mon, 16 Apr 2007 20:28:18 GMT

Hello Tatyana

The only possible reason I see is that you do no save the imported instance into the public instance attributes. Presumably the coding of your CONSTRUTOR method is missing the following coding:

Recommendation: rename your instance attribute, e.g.

class screen_init definition.
public section.
    data: mo_textedit type ref to CL_GUI_TEXTEDIT,
            mo_tree type ref to cl_gui_simple_tree.
class screen_handler definition.
  public section.
 data: mo_textedit type ref to CL_GUI_TEXTEDIT,
          mo_tree type ref to cl_gui_simple_tree  

"       Create event handler instance
        Create object  event_handler
           exporting textedit = textedit  " instance IS BOUND
                      tree = tree.               " instance IS BOUND

" Here we are inside the CONSTRUCTOR
method CONSTRUCTOR.

  me->mo_textedit = textedit.  " save the imported instance to instance attribute
  me->mo_tree      = tree.       "  dito

endmethod.

Regards

Uwe

Re: Class parameters not seen in all methods

Former Member — Mon, 16 Apr 2007 23:21:33 GMT

I agree with Uwe.

Just a small clarification. I think the attributes need to be decalred either as private or protected attribiutes else the concept of having a OOP program is not very much justified.

Cheers

Kareem

Re: Class parameters not seen in all methods

uwe_schieferstein — Tue, 17 Apr 2007 06:23:31 GMT

... and I agree with Kareem.

However, even SAP standard classes have often public instance attributes (e.g. CL_REBD_BUILDING->ms_detail) but then they are defined as <b>read-only</b>.

Regards

Uwe

Re: Class parameters not seen in all methods

Former Member — Tue, 17 Apr 2007 14:50:02 GMT

Guys,

I can't express how much you helped me.

I am new to ABAP though with the years with other programming languages experience.

The 2 lines below were the key to resolve the problem.

me->textedit = textedit.  " save the imported instance to instance
                           "attribute
  me->tree      = tree.       "  dito

Thank you very much!