ABAP_to_the_Future

7
Exception Classes and Design by Contract
create an (optional) importing parameter with the same name as the attribute so
that every time the exception is raised the programmer can (optionally) pass on
that information to the instance of the exception class that is generated.
Later on, when you start processing instan ces of your exception class, you’ll be
very grateful that you have a mechanism to store such data and pass it onwards
into routines to analyze and respond to the error.
7.2.2 Declaring the Exception
For two of the three types of exception class (CX_STATIC_CHECK and CX_DYNAMIC_
CHECK), you have to specify the exception class in the signature of the method that
raises the exception. If you do have to specify the exce ption, then you do so in
Transaction SE24 by navigating to a method name in your class and clicking the
Exceptions button. The screen shown in Figure 7.4 appears.
Figure 7.4 Adding Exceptions to Global Class Methods
You just have to add one or more exception classes to the table in Figure 7.4; the
descriptions will fill themselves out.
As you can see in Figure 7.4, when you try to add a class-based exception to a
global method, amazingly, the Exception Classes checkbox is not selected by
default. Without that box selected, global methods can have exceptions that will
behave just like a function module, giving a list of exceptions that set the value of
SY-SUBRC. Luckily, the system is clever enough to recognize that a class starting
with ZCX is an exception class and will therefore select the Exception Classes box
for you.
If you’re going to declare the exception class in the signature of the method, then
the name of the exception class must make sense to the caller (i.e., it cannot be
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