ABAP_to_the_Future

Defining BAdIs 6.3
Why would you want to call more than one BAdI implementation? As an example,
say that your BAdI is to be called when you’re saving a database record.
When saving the main record, you may want to update some Z tables, send messages
to external systems, send emails, start a workflow, and have SAP recite a
poem to the user (you can actually make SAP do just that, but it’s probably best
not to describe how to do so here). Each of these tasks is unrelated to the others,
and not all are done by each country. Th e United States may send an email and
start a workflow, Germany may do only the Z table updates, Australia might do
everything, France may just recite the poem, and Poland may do nothing at all. In
this case, you define one BAdI implementa tion for each of these assorted tasks,
and then set a filter for the countries that are going to use that task.
Note
In a really complicated application you often find that several developers want to work
on the same part of the program at once for different reasons. If the assorted tasks mentioned
previously were in one big routine, then any developer changing one part of that
routine would lock the whole thing; you could end up in a crazy situation in which you
have six development requests all needin g to be solved by changing user exit
MV45AFZZ and so they have to go into a queue. Solving this problem is just another
bonus to the BAdI approach.
The next screen area in Figure 6.14 is titled Instance Creation Mode . Sometimes,
you want to buffer the data inside your BAdI so that if it gets called twenty
times in a row the program doesn’t have tokeep going to the database or recalculating
all the values. Other times, however,you do want to reread the database or
recalculate the values each time.
To make sure the data inside the BA dI is created anew each time, choose Newly
Created Instantiation. If you are happy with just reusing the same data each
time, then choose Reusing Instantiation. The latter is the singleton pattern, in
which only one instance of a class can ever exist.
The bottom of the screen shown in Figure 6.14 star ts talking about a fallback
class; Section 6.4 addresses creating and dealing with such a beast.
Defining a Filter
The next step in creating the BAdI definition is to define a filter (look at the middle
of the left-hand side of the screen shown in Figure 6.14). You’ll see an icon
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