What does it do? A variant of the external subroutine call that is not allowed in classes. The statement PERFORM calls the statically specified subroutine subr of a statically specified program prog.
The existence of the specified program and subroutine is not checked by the syntax check. Only the extended program check reports a nonexistent program or subroutine as an error by default. If the addition IF FOUND is specified, the extended program check does not perform a check either.
If the specified subroutine or program does not exist at runtime, a catchable exception of the class CX_SY_DYN_CALL_ILLEGAL_FORM or CX_SY_PROGRAM_NOT_FOUND is raised by default. If the addition IF FOUND is specified, the statement PERFORM is skipped.
Latest notes:
In this variant, the program name prog is specified directly in parentheses. Since parentheses in operand positions indicate a dynamic specification in all other cases, this form of the name is obsolete. The specification with the addition IN PROGRAM should be used instead.
External calls of subroutines are obsolete anyway. Instead of subroutines, methods and function modules can be used as explicit functional interfaces of a program.
Furthermore, external calls of subroutines are critical, since it cannot usually be statically determined to which program groups the compilation unit is assigned. ABAP_HINT_END
