ABAP_to_the_Future

Designing Exception Classes 7.2
related to any internal implementation details of the method that raises the
exception). The caller does n’t need to know how the called routine works, just
that it failed in some wa y; therefore, a name like CX_NO_RECORD_FOUND is better
than CX_READ_ON_TABLE_XYZ_FAILED.
7.2.3 Raising the Exception
In traditional function modules, exceptions were raised via the RAISE EXCEPTION
construct. Now, there is the obviously better RAISE EXCEPTION TYPE construct.
(It’s obviously better because it has one more word and is close enough to the old
syntax to thoroughly confuse everyone.)
In order to raise class-based exceptions using the new RAISE EXCEPTION TYPE construct,
you need to have a TRY/CATCH/CLEANUP block, which some traditional ABAP
programmers don’t like the look of, because it seems much more complicated
than just saying IF SY-SUBRC <> 0. An example of catching a class-based exception
is shown in Listing 7.3; as you can see, there are no commands that do anything;
it just describes the structure of the error handling block. Each section has
a clear task to do, and in each section yo u call a method to do that section’s task
(i.e., the proper pu rpose of the method or error handling or cleaning up). This
approach obeys the wise words of one of the fathers of OO programming, Robert
Martin, who once said, “Each method sh ould do one thing only, and error handling
is one thing.”
Thus, there is a clear separation of concerns. In Listing 7.3, the DO_SOMETHING
method does the real work of the application and cares not about how errors are
handled. The HANDLE_THIS_EXCEPTION method, on the other hand, is solely concerned
about handling an error and cares not about the real business of the application.
You should always aim for this approach when writing TRY/CATCH/CLEANUP
blocks.
METHOD main.
* Local Variables
DATA: lcx_monster_exception
TYPE REF TO ycx_monster_exception,
lcx_monster_exception_mc
TYPE REF TO ycx_monster_exception_mc.
TRY.
do_something( ).
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