Comments
ABAP PERFORM FORM Statement syntax, information and example SAP source code
PERFORM - subr_identifier
Short Reference
ABAP Syntax ... subr
| {subr|(sname) IN PROGRAM [prog|(pname)] [IF FOUND]}
| {n OF subr1 subr2 ...} ... .
ABAP_ALTERNATIVES:
1 ... subr ... .
2 ... subr|(sname) IN PROGRAM [prog|(pname)] [IF FOUND] ... .
3 ... n OF subr1 subr2 ... .
What does it do? These names are used to specify subroutines, whereby
subr is the name of the subroutine declared in the statement FORM , and prog is the name of an ABAP program. sname and pname are character-like fields that contain the name of a subroutine or a program when a statement is executed.
Latest notes: As well as the alternatives shown here, there is another obsolete form of the external subroutine call.
ABAP_ALTERNATIVE_1 ... subr ... .
What does it do? subr can be used to call any subroutine of the current program. The subroutine must exist.
ABAP_ALTERNATIVE_2
What does it do? This specification is used to call any subroutine of another program or the current program. The subroutine and the program can either be specified statically as subr and prog (static external subroutine call), or dynamically in the parenthesized character-like fields sname and pname . When the statement is executed, sname and pname must contain the name of a subroutine or program in uppercase (dynamic external subroutine call).
If an external subroutine is statically specified, the syntax check does not check whether the specified program and subroutine exist. Only the extended program check registers any nonexistent programs or subroutines as errors by default. If the addition IF FOUND is specified, the extended program check also skips the check.
If the statically or dynamically specified subroutine or program does not exist at runtime, a handleable 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.
If the specified program is available, it is loaded, if required, into the internal session and scanned for the specified subroutine. The event
LOAD-OF-PROGRAM is not triggered. If the subroutine is available, the event LOAD-OF-PROGRAM is triggered (if not already triggered) and then the subroutine is executed.
Latest notes: External calls of subroutines are almost completely obsolete. 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 there is usually no static way of determining which
program groups are assigned to the frame program.
To call a subroutine in a program of another package, the definition of the subroutine must be shared between a declaration part and an implementation part using the additions
DEFINITION and IMPLEMENTATION . The declaration part must be published in the package interface.
If no further addition is specified apart from IN PROGRAM (no IF FOUND , no parameter list ), the program name can be omitted and is added implicitly with the name of the current program.
Specifying a subroutine dynamically is one of the dynamic programming techniques. See Dynamic Calls .
ABAP_ALTERNATIVE_3 ... n OF subr1 subr2 ... .
What does it do? This specification selects a subroutine subr of the current program from a list. The list subr1 subr2 ... can contain up to 256 directly specified subroutines. n must be a numerical data object containing a number between 1 and the specified number of subroutines when the statement is executed. The subroutine subr is called, whose list position is in n . In this variant, it is not possible to specify parameter_list and only subroutines without a parameter interface can be called.
Example ABAP Coding This example calls n internal subroutines
subr_1 through subr_n successively from a list.
DATA n TYPE i.
...
DO n TIMES.
PERFORM sy-index OF subr_1 subr_2 ... .
ENDDO.
FORM subr_1.
...
ENDFORM.
FORM subr_2.
...
ENDFORM.
...
Documentation extract taken from SAP system, � Copyright SAP AG. All rights reserved
