ABAP_to_the_Future

6
The Enhancement Framework and New BAdIs
to quote Steerpike from the novel Gormen ghast, “What are problems for, if not
for solving?”). The next problem is that in two countries a standard monster is
handled the same way, in the United Stat es it’s handled a different way, and in
Australia nothing needs to be done at that point in the program. One way (not a
good way) of addressing this problem is demonstrated in Listing 6.2.
IF ( ld_land = 'DE' OR ld_land = 'GB' ) AND
ld_monster_type IN gr_standard_monster.
PERFORM something.
ELSEIF ld_land = 'US' AND ld_monster_type IN gr_standard_monster.
PERFORM something_else.
ELSEIF ld_land = 'AU' AND ld_monster_type IN gr_standard_monster.
* Don't do anything
ENDIF.
Listing 6.2 A Suboptimal Way of Coding Logic that Varies by Country
This code has conditional logic based on the country, so you keep having to
change the code for each new country adde d. To fix this problem, this is where
you need to take a leaf out of SAP’s book and define a BAdI. In such a situation,
SAP uses a BAdI, and if it is good enough for SAP, then it’s good enough for me.
Defining a BAdI is quite a complicated process, to put it mildly. One of the goals
of OO programming is abstraction (to sepa rate the things that change from the
things that stay the same), and sometimes to achieve a good level of abstraction
things have to be more complicated (have more layers) than you would find in
the procedural world. Creating a BAdI is rather like a Russian nesting doll: Each
time you create a doll, you then create a bigger one to put the last one into. The
outside world (the calling program) only sees the outermost doll; all the complexity
is hidden inside.
There are three main steps in defining a BAdI: creating an enhancement spot, creating
the BAdI definition, and creating th e BAdI interface. Each of these steps is
discussed next.
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