ABAP_to_the_Future

Types of Exception Classes 7.1
declared in the routine signature. In essence, you can throw the exception object
up in the air, and it will travel up the call stack looking for an appropriate handler.
It will stop at the first one it finds, and if it can’t find any, then a short dump will
occur.
In most documentation, this type of exception class is described as being useful
for problems that can occur anywhere (such as the system running out of memory),
and it would clearly be impractical to declare a long list of such exception
classes in every single method signatur e throughout the system. However, this
also has a much wider application. As an example, say that you have an interactive
ALV list program that calls a Mon ster Monitor. The Monster Monitor displays
a list of active monsters, and you can select a monster by clicking the checkbox
next to the monster. Then, you can choose one of 15 icons along the top of
the screen to issue various commands to that monster. The code for this is shown
in Listing 7.2.
FORM user_command USING id_ucomm TYPE sy-ucomm
is_selfield TYPE slis_selfield.
TRY.
PERFORM get_chosen_monster USING is_selfield
CHANGING mo_chosen_monster.
PERFORM lock_monster USING mo_chosen_monster.
CASE id_ucomm.
WHEN 'HOWL'.
mo_chosen_monster->howl_at_moon( ).
WHEN 'TERROR'.
mo_chosen_monster->terrorise_village( ).
WHEN 'SUBPRIME'.
"Most monstrous activity possible
mo_chosen_monster->sell_mortgages( ).
"Etc...
WHEN OTHERS.
MESSAGE 'Function is not available' TYPE 'I'.
ENDCASE.
CATCH zcx_bc_user_cancelled.
MESSAGE 'Processing Cancelled'(349) TYPE 'S'.
PERFORM unlock_monster USING mo_chosen_monster.
RETURN.
ENDTRY.
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