IBM AS/400 manual Creating an Application Using Multiple Procedures, Multiple Procedures Module

Multiple Procedures Module

Chapter 4. Creating an Application Using Multiple

Procedures

The ability to code more than one procedure in an ILE RPG module g enhances your ability to code a modular application. This chapter di and how you might use such a module in your application. Specifically presents:

¹ Overview of key concepts

¹ Example of module with more than one procedure

¹Coding considerations

Refer

to

the

end

of

this

section

to

see

where

to

look

for

more

on

coding

modules

with

multiple

procedures.

A

Multiple Procedures

Module

—

Overview

An

ILE

program

consists

of

one

or

more

modules;

a

module

is

made

up

more proceduresprocedure. A

is any piece of code that can

be

called

bound call. ILE RPG has two kinds of procedures: a main

procedure

a

cedure.

The

way

to

call

a

subprocedure

is

with

a

prototyped

call.

Note:

In the RPG documentation, the term 'procedure' refers to both

subprocedures.

Main

Procedures and

Subprocedures

An ILE RPG module consists

of

a

main

procedure

and

zero

or

more

sub

dures.

(If

there

are

subprocedures,

the

main proceduremain -

is

optiona

dure

is

a

procedure

that can be specified as the program entry

receive

control

when

an

ILE

program

is

first

called). The

main

procedu

in

themain

source section

,

which

is

the

set

of

H,

F,

D,

I,

C,

and

O

s

that

begin

a

module.

In

V3R1,

all

ILE

RPG

modules had

a

main

proce

other

procedures.

A

subprocedure

is a procedure that is specified after the main sou

subprocedure

differs

from a

main

procedure

primarily

in

that:

¹Names that are defined within subprocedure are not accessible o subprocedure.

¹	No cycle		code is generated for the subprocedure.
¹	The	call	interface must	be	prototyped.
¹	Calls	to	subprocedures	must	be bound procedure calls.

¹Only P, D, and C specifications can be used.

Subprocedures can provide independence from other procedures because items are local. Local data items are normally stored in automatic st means that the value of a local variable is not preserved between cedure.

 Copyright IBM Corp. 1994, 1999 33