Take care if input and output could be the same

Generally, it is a good idea to clear the parameter as a first thing in the method after type and data declarations. This makes the statement easy to spot and avoids that the still-contained value is accidentally used by later statements.

However, some parameter configurations could use the same variable as input and output. In this case, an early CLEAR would delete the input value before it can be used, producing wrong results.

" anti-pattern
DATA value TYPE i.

square_dirty(
  EXPORTING
    number = value
  IMPORTING
    result = value ).

METHOD square_dirty.
  CLEAR result.
  result = number * number.
ENDMETHOD.

Consider redesigning such methods by replacing EXPORTING with RETURNING. Also consider overwriting the EXPORTING parameter in a single result calculation statement. If neither fits, resort to a late CLEAR.