DEFINE
[SUBROUTINE]
subroutine-name
|
||
statement
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|
|
END-SUBROUTINE
|
|
RETURN (reporting mode only)
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This document covers the following topics:
For an explanation of the symbols used in the syntax diagram, see Syntax Symbols.
Related Statements: CALL | CALL FILE | CALL LOOP | CALLNAT | ESCAPE | FETCH | PERFORM
Belongs to Function Group: Invoking Programs and Routines
The DEFINE SUBROUTINE statement is used to define a Natural
subroutine. A
subroutine is invoked with a PERFORM statement.
A subroutine may be defined within the object which contains the
PERFORM statement that
invokes the subroutine (inline
subroutine); or it may be defined external to the object that
contains the PERFORM statement (external subroutine). An inline
subroutine may be defined before or after the first PERFORM
statement which references it.
Note:
Although the structuring of a program function into multiple
external subroutines is recommended for achieving a clear program structure,
please note that a subroutine should always contain a larger function block
because the invocation of the external subroutine represents an additional
overhead as compared with inline code or subroutines.
Any processing loop initiated within a subroutine must be closed
before END-SUBROUTINE is
issued.
An inline subroutine must not contain another DEFINE
SUBROUTINE statement (see Example 1 below).
An external subroutine (that is, an object of type subroutine) must
not contain more than one DEFINE SUBROUTINE statement block (see
Example 2
below). However, an external DEFINE SUBROUTINE block may contain
further inline subroutines (see Example 1 below).
The following construction is possible in an object of type subroutine, but not in any other object (where SUBR01 would be considered an inline subroutine):
... DEFINE SUBROUTINE SUBR01 ... PERFORM SUBR02 PERFORM SUBR03 ... DEFINE SUBROUTINE SUBR02 /* inline subroutine... END-SUBROUTINE ... DEFINE SUBROUTINE SUBR03 /* inline subroutine... END-SUBROUTINE END-SUBROUTINE END
The following construction is not allowed in an object of type subroutine:
... DEFINE SUBROUTINE SUBR01 ... END-SUBROUTINE DEFINE SUBROUTINE SUBR02 ... END-SUBROUTINE END
| subroutine-name |
For a subroutine name (maximum 32 characters), the same naming conventions apply as for user-defined variables, see Naming Conventions for User-Defined Variables in the Using Natural documentation. The subroutine name is independent of the name of the module in which the subroutine is defined (it may but need not be the same). |
|---|---|
| END-SUBROUTINE | The subroutine definition is terminated with
END-SUBROUTINE.
|
| RETURN | In reporting mode, RETURN may also be used to terminate a subroutine. |
This section covers the following topics:
No explicit parameters can be passed from the invoking program via the
PERFORM statement to an
internal subroutine.
An inline subroutine has access to the currently established global data area as well as to the local data area used by the invoking program.
An external subroutine has access to the currently established global
data area. In addition, parameters can be passed directly with the
PERFORM statement from the
invoking object to the external subroutine; thus, you may reduce the size of
the global data area.
An external subroutine has no access to the local data area defined in the calling program; however, an external subroutine may have its own local data area.
** Example 'DSREX1S': DEFINE SUBROUTINE (structured mode)
************************************************************************
DEFINE DATA LOCAL
1 EMPLOY-VIEW VIEW OF EMPLOYEES
2 NAME
2 ADDRESS-LINE (A20/2)
2 PHONE
*
1 #ARRAY (A75/1:4)
1 REDEFINE #ARRAY
2 #ALINE (A25/1:4,1:3)
1 #X (N2) INIT <1>
1 #Y (N2) INIT <1>
END-DEFINE
*
FORMAT PS=20
LIMIT 5
FIND EMPLOY-VIEW WITH NAME = 'SMITH'
MOVE NAME TO #ALINE (#X,#Y)
MOVE ADDRESS-LINE(1) TO #ALINE (#X+1,#Y)
MOVE ADDRESS-LINE(2) TO #ALINE (#X+2,#Y)
MOVE PHONE TO #ALINE (#X+3,#Y)
IF #Y = 3
RESET INITIAL #Y
PERFORM PRINT
ELSE
ADD 1 TO #Y
END-IF
AT END OF DATA
PERFORM PRINT
END-ENDDATA
END-FIND
*
DEFINE SUBROUTINE PRINT
WRITE NOTITLE (AD=OI) #ARRAY(*)
RESET #ARRAY(*)
SKIP 1
END-SUBROUTINE
*
END
SMITH SMITH SMITH
ENGLANDSVEJ 222 3152 SHETLAND ROAD 14100 ESWORTHY RD.
MILWAUKEE MONTERREY
554349 877-4563 994-2260
SMITH SMITH
5 HAWTHORN 13002 NEW ARDEN COUR
OAK BROOK SILVER SPRING
150-9351 639-8963
Equivalent reporting-mode example: DSREX1R.
** Example 'DSREX2': DEFINE SUBROUTINE (using GDA fields) ************************************************************************ DEFINE DATA GLOBAL USING DSREX2G END-DEFINE * INPUT 'Enter value in GDA field' GDA-FIELD1 * * Call external subroutine in DSREX2S * PERFORM DSREX2-SUB * END
1 GDA-FIELD1 A 2
** Example 'DSREX2S': SUBROUTINE (external subroutine using global data) ************************************************************************ DEFINE DATA GLOBAL USING DSREX2G END-DEFINE * DEFINE SUBROUTINE DSREX2-SUB * WRITE 'IN SUBROUTINE' *PROGRAM '=' GDA-FIELD1 * END-SUBROUTINE * END