9/24/2007 ©Countrywide Home Loans, 2002-2003, All rights reserved 1

Free Form RPGFree Form RPGFree Form RPGA few notes about the use

Of Free Form RPG

Presented by:

Jim Low

Arturo Duarte, Jr.

Wednesday, September 25, 2002

9/24/2007 2

RPG IV Free Form Discussion

Topics

� Software Development Improvements

� Faster Coding

� Easier to Understand

� More Built in Functions (BIFs)

� A Few Less Op Codes

� What We Discovered

� Information Sources

� Significant Op Code Changes

� A Look into the Future

� Conclusion: Free-Form Advantages

� Examples of RPGIII v Free-Form

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Software Development

Improvements

�Faster Coding

�Easy to understand

�A few more BIFs

�A few less Op Codes

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Faster Coding

�Easy to start and end Free Form

– Calculation section start with: /Free (column 7)

– Calculation section end with: /End-Free (column 7)

�Don’t have to deal with columns

– Algebraic Expressions (i.e. X = (Y * Z)/A)

– Type like you read – Left to Right

– Finally do what you profess – get rid of indicators! (mostly)

– Compound IF statements (complex)

– Simple IF statements

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Easier to Understand

� Reading a file

– ReadE(EN) filekey filename;

– Compared to:

• C FileKey ReadE(EN) filename

• C Read(EN) filename

� Calling a subprocedure

– Procname(P1 : P2 : P3 : … : Pn);

– Compared to:

• CALL ProcName PLIST

• CALLP ProcName(P1 : P2 : . . . : Pn)

• EVAL RtnValue = ProcName(P1 : P2 : … : Pn)

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Easier to Understand (Continued)

� Perform date calculations inline or as a conditional

– Old way:• C Extrct SomeDate:*M MM

– Better way:• MM = %SubDt(SomeDate:*Month);

– Even better:• If %SubDt(SomeDate:*Month) = ReportMonth;

� Date Conversion:– newDateFormat = %char( %date( oldDateFormat: *YMD): *MDY) ;

� Handle in line errors easier– Monitor, On-Error, EndMon Operations for entire blocks of code

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A few more BIFs (Built-in-Functions)

�%LookUp, %LookUpXX (LT;LE;GT;GE)

�%Minutes; %Months (converts argument to duration

values for arithmetic operations)

�%Occur (Set occurrence of a multiple occurrence data structure)

�%SHTDN (determining if the operator has requested shutdown)

�%CHAR (Input Value to character conversion – includes

numeric, date, time, timestamp, graphic, and UCS-2)

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A Few Less Op Codes (Not Allowed in

Free-Form Coding)

�Move operations

– MOVEA; MOVELL; MOVEHL; MOVELH; MOVE

�Bit Operations

– BITON; BITOFF; TESTB

�And others (see iSeries News; Moving Forward with Free-Format

RPG)

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What we Discovered

�An overall 10% improvement in programming

speed (based on measurement of time to create new Display File

programs for CHL-CHL Refi Application)

�Compliance with numeric vs. alpha field handling (i.e. like fields to like fields)

�Clarity in programming

�A strong need for Best Practices (better yet: Standards)

�Think about what is needed first (i.e. define needed

variables then develop solution)

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What we Discovered (Continued)

�A number of similarities between Free-

Form and Java.

�Anyone can follow the code.

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Information Sources

�IBM RPG/LE V5R1/V5R2 manuals

�iSeries News

�Contact with other experts (both in house and

external).

�Experience with coding (using both traditional and

current technology).

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Significant Op Code Changes

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Significant Op Code Changes

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Significant Op Code Changes

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A look into the Future

�V5R2 Enhancements

– Eliminate the need for KLIST/KFLD

– Single stroke operands (i.e. +=; -=; /=; etc.)

• FLD1 += 1;

• ADD 1 FLD1

• EVAL FLD1 = FLD1 + 1

– BitWise BIFs (%BITAND; %BITOR; %BITXOR; etc.)

– Complex Data Structures (DIM use at the DS line level;

DIM on each sub-field; and DIMs within each sub-field)

– Update only selected fields

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A look into the Future (Continued)

�V5R2 Enhancements (Continued)

– BitWise BIFs (%BITAND; %BITOR; %BITXOR; etc.)

• Result = %BitOr(Var.1 : Var.2 : . . . : Var.n);

– Complex Data Structures (DIM use at the DS line level;

DIM on each sub-field; and DIMs within each sub-field)• D DSName DS 100 DIM(100)

• D DSSub1 20 DIM(5)

• D DSSub1a 5 DIM(4) Overlay(DSSub1)

– Update only selected fields

• UPDATE(EN) (Fld1 : Fld2 : Fld3) FileName;

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Conclusion: Free-Form

�Is Quicker

�Is Easier to Understand

�Helps enforcement of good programming

practices

�Takes advantage of current coding

technology

�Supports business vision and strategic

initiatives.

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Examples of RPGIII v FreeForm

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Examples of RPGIII v FreeForm

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Examples of RPGIII v FreeForm

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Examples of RPGIII v FreeForm

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Examples of FreeForm/CODE400