HP 3000 Manuals HP 3000 Manuals
Establishing and Using Standards
Standards provide the framework for building efficient RPG programs.
Programming standards decrease development and maintenance time and
improve the legibility of programs. System standards, such as file
naming conventions and account and group standards make it easier to
build and maintain multi-program applications.
The next six sections in this chapter suggest general RPG programming
standards you may want to adopt.
Using Comments
This section contains tips on how to use comments in an RPG program. A
general rule of thumb is that a well-documented program is one-third
comments.
* Enter comments for all Input and Output record types.
* Enter comments for all Calculation Specification GOTO operations.
* Enter notes in columns 60-74 on important Calculation Specifications.
* Maintain a "Date-Modified" comment line at the beginning of each
program. Also develop a scheme to keep track of program
modifications. For example, you can use the Sequence Number Field
(columns 1-5) to document changes. For lines added on 02/28, enter
A0228. For lines that are modified, enter C0228. "Comment out"
deleted lines and enter D0228 on them.
* Develop consistent standards and style.
Using Structured Programming Techniques
Structured programs are easier to develop, test and maintain. They are
also easier to understand.
* Replace repetitive code segments with subroutines (EXSR).
* Stick to sequential logic in the Calculation Specifications. Try to
avoid GOTO operations. Instead, use the combinations: IF-THEN-ELSE,
IF-THEN, DO-WHILE, DO-UNTIL.
Standardizing Field Names
Use field names that are:
* Five characters long
A 5-character name can be prefixed or suffixed. For example, if a
last name field is called LNAME, it can be prefixed by T when used in
an Output Specification for a Terminal file.
* Meaningful
Names that relate to the contents or purpose of a field are easier to
understand and make programs more readable. Also use similar names
for arrays and their associated counters. For example, the counter
for array AMT can be A.
* Used consistently in other programs
You can use the $COPY/$INCLUDE statements to get field definitions
from a source library (see "Using Source Libraries" in Chapter 6).
For RPG programs running under MPE V, fields that are not used in a
program increase the size of the data space at both compile-time and
run-time.
Standardizing the Use of Indicators
Use this indicator: For:
01-09 Input Specification records
10 Input Specification flush indicator
11-19 Input Specification fields
20-59 General-purpose Calculation Specification
operations
60-69 CHAIN or READ resulting indicators
70-79 External subroutines.
80-89 Exception output
90-98 Work (reusable) indicators
99 First-time indicator
Standardizing File Names
Use this prefix For this type of file:
(or suffix):
B Batch
C Catalog
D Data
I Input
J Job
K KSAM key
N Notes
P Executable program
R RAF
S Source programs or sorted output
T Temporary
W Work
Standardizing MPE Group Names
Use this Group name: For:
DATA MPE, KSAM, TurboIMAGE files; operator logon group
DOC User documentation
FORMS VPLUS and SIGEDITOR forms
JOB Job streams
PROGRAM Executable programs
PUB UDCs, user notes, temporary and scratch files
SOURCE Source programs, schemas and program documentation