如何在 SALV 表上调用 remove_column？

Question

I want to execute the method remove_column on an instance of cl_salv_column_table but because of its visibility level, I am not able to do so.

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Plan:

I already tried inheriting from cl_salv_columns_list and then perform the call inside the remove -method:

CLASS lcl_columns_list DEFINITION INHERITING FROM CL_SALV_COLUMNS_LIST.
    PUBLIC SECTION.
    METHODS:
        remove IMPORTING iw_colname TYPE string.
ENDCLASS.

But apparently my casting knowledge got rusty as I'm not able to figure out an appropriate solution.

This is my current hierarchy - the red arrows show the way I would have to take:

My approach looks like this:

DATA lo_column_list TYPE REF TO lcl_columns_list.
lo_column_list ?= CAST cl_salv_columns_list( lo_columns ).

But it fails with:

 CX_SY_MOVE_CAST_ERROR Source type: \\CLASS=CL_SALV_COLUMNS_TABLE Target type: "\\PROGRAM=XXX\\CLASS=LCL_COLUMNS_LIST"

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Background:

My task is to select all columns of 3 tables (which would be done like SELECT t1~*, t2~*, t3~* ... ) as long as their names don't conflict (eg field MANDT should only be displayed once). This would require defining a very big structure and kick the size of the selection list to a maximum.

To avoid this, I wanted to make use of the type generated by my inline-declaration. Hiding the individual columns via set_visible( abap_false ) would still display them in the layout manager - which looks really ugly.

Is there any other way to accomplish my target?

Answer 1

Use set_technical( abap_true ) to hide the columns entirely. As for your approach - sorry, inheritance does not work that way - in no statically typed object oriented language that I know. You can't 'recast' an instantiated object to a different class. You would need to modify the framework extensively to support that.