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ABAP Keyword Documentation → ABAP − Reference → Declarations → Declaration Statements → Classes and Interfaces → ABAP Objects - Overview → Classes → Components of Classes → Methods →
Interface Parameters in Methods
Interface parameters in methods are input parameters (IMPORTING, CHANGING parameters) and output parameters (EXPORTING, CHANGING, RETURNING parameters). In declarations with the statements
the following attributes are determined:
Passing parameters by reference or by value
With the exception of the return value (RETURNING parameters), parameters
can be passed both by value or reference. Passing by reference is standard with methods. If only a name
p is specified in the parameter declaration, the parameter is passed implicitly
as a reference. If a VALUE(p) is specified instead,
then the parameter is passed as a value. The return value may only be passed as a value. Passing by
reference can also be explicitly specified with other parameters using REFERENCE(p).
An IMPORTING parameter transferred by reference, cannot be changed in the method.
Typing parameters
All parameters must be typed
during declaration using the addition TYPE or the
addition LIKE. The following entries are allowed after TYPE as parameter types:
Optional parameters
All input parameters (IMPORTING, CHANGING parameters) can be defined in the declaration as optional parameters using the additions OPTIONAL or DEFAULT. These parameters must not necessarily be transfered when the method is called. With the addition OPTIONAL your parameter remains initialized according to type, while the addition DEFAULT allows you to enter a start value.