AZK RPG - Modular Programs with Procedures

- system looking for called program dynamically, during the run-time

- the calling and called components are bound together into a single *PGM object

- a first user-written code that executes when program runs

- is a self-contained, identifiable collection of RPG statements, w/i a program that performs a specific task and returns to the caller

• - can be
•      - created independently from the rest of the program
•      - coded in separate source member
•      - compiled in separate module
•      - binded together when program is created
• - using local variables defined in the procedure
• - is recursive (can call itself)
• - can return a value to its caller outside the context of any parameter variables

• Dcl-proc Celcius;
•        // Procedure Interface
•    Dcl-pi *N Int(5);  // Int(5) - data attributes of the return value     
•       Fahrenheit Int(5);   // accepts one parm Fahrenheit Int(5)
•    End-pi;
• .
•    Dcl-s Temperature Int(5);  // - declaration of the return variable
• .
•    Eval(H) Temperature = (5/9) * (Fahrenheit - 32);
•    Return Temperature;   // - returns variable's value (not variable itself)
• End-proc;

• - *N - NO interface name b/c subpr can have only one interface
• - Int(5) - data attributes of the return value
•    - subpr can have only SINGLE return value
•       - can be DS (using Likeds keyword)
•       - can be array (using Dim keyword)
• - this subpr accepts one parm Fahrenheit Int(5)

• - makes local var to preserve (keep) it's value b/w calls
• - will keep file opened for the next time the program call the procedure

• Dcl-s Temperature Int(5) Static;
• Dcl-f Customer Static;

• - to return value
•    Return Temperature;

• - return value can be expression or literal
•    Return (5/9) * (Fahrenheit - 32);

• - should be included within subpro source member, but outside the subpro
• .
• Dcl-pr Celcius Int(5);
•    *N Int(5);
• End-pr;

• - Metrictemp keeps returned value
•      Metrictemp = Celcius(Englichtemp);
• .
• - caller can be comparison expression
•      If Celcius(Englichtemp) > 100;
•      Endif;

- includes subprocedure w/i the same source (local procedure)

• - does NOT include the RPG cycle
• - main section does not include any executable code, only global declarations
• - there is NO *Inlr - does not cleanup or close any resources
• - is recursive (can call itself)
• - when program starts implicitly...
•      - initializes variables
•      - locks data areas
•      - open files
• - when program ends...
•      - program must explicitly cleaned up or close all resources using operations
• - Ctl-opt 'Main' kw is a key to create a Linear program
•      - explicitly names a procedure to be the Main Procedure
• .
• Ctl-opt Main(Driver);

• - contain only global declarations and subprocedures that can be combined w other modules to create a program
• - by itself it cannot create an object
• - Ctl-opt 'Nomain' kw is a key to create a Nomain Module
• .
• Ctl-opt Nomain;

• - is a key to create a Linear program and specify main procedure in Linear Program
• Ctl-opt Main(proc-name);

• - is a key to create a Nomain Module
• Ctl-opt Nomain;

• - allows procedure to be called from outside of Nomain Module
• - w/o Export, procedure can be executed only from another procedure w/i this module
• Dcl-proc proc-name Export;

• CRTBNDRPG
•    - combines 2 program creation steps
•       1) Compile - creates *Module object
•       2) Bind - creates *Pgm object

• - command to create single-module program
• - combines 2 program creation steps
•       1) Compile - creates *Module object
•       2) Bind - creates *Pgm object

• 1) CRTRPGMOD (compile) - creates RPG *Module object
•      - contains compiled executable code
•      - can not be run by itself
• 2) CRTPGM (bind) - creates *Pgm object
•      - physically copies compiled code from the modules into a program object
•      - creates runable program

• - to create multiple-module program single entry-point program
• - CRTPGM (bind) - creates *Pgm object
• - binding step that physically copyes the compiled code from the module into program

• - to create multiple-module program single entry-point program - *Pgm Object
• - binding step that physically copyes the compiled code from the module into program
• - supports subprocedures and linear programs
• - entry point is a module which suppose to have Main Procedure
• - module can be written by any ILE language
• .
• CRTPGM PGM(pgm-name)  +  - name of the final program object
•      MODULE(module-llist) +  - list of the modules to bind (up to 300)
•      ENTMOD(entry-module)    - which of those modules is the entry module
• .
• CRTPGM PGM(ANATOLIYK/CEL_MODE)
•      MODULE(ANATOLIYK/CEL_MODE ANATOLIYK/CELSIUS) +
•      ENTMOD(ANATOLIYK/CEL_MODE)

- an object (type *Bnddir) that contains a list of the modules and service programs

CRTBNDDIR

• WRKBNDDIRE
•      - To update (add or delete modules or Srv Pgm) Binding directory
• .
• WRKBNDDIRE BNDDIR(MOD_BNDDIR)

• DSPBNDDIR
•      - To display Binding directory
• .
• DSPBNDDIR BNDDIR(MOD_BNDDIR)

• CRTPGM PGM(DRI_MAIN)      // - name of the final program object 
•    MODULE(DRI_MAIN)   // - defaults to using a module w the same name as program
•    ENTMOD(DRI_MAIN)   // - defaults to using the first listed module
•    BNDDIR(MOD_BNDDIR) // - binding directory name

• CRTPGM PGM(DRI_MAIN)      // - name of the final program object
•    BNDDIR(MOD_BNDDIR)  // - binding directory name

• UPDPGM
•    - lets you list just the module(s) that you want to replace from original program with the new version of module(s)
•    - performs the same function as CRTPGM, except that it replaces only module(s) from the list
• .
• UPDPGM PGM(ANATOLIYK/DRI_MAIN)
•    MODULE(ANATOLIYK/DRI_MAIN ANATOLIYK/CEL_NOMAIN)

• - lets you list just the module(s) that you want to replace from original program with the new version of module(s)
•    - performs the same function as CRTPGM, except that it replaces only module(s) from the list
• .
• UPDPGM PGM(ANATOLIYK/DRI_MAIN)
•    MODULE(ANATOLIYK/DRI_MAIN ANATOLIYK/CEL_NOMAIN)

• - it does NOT share storage address w called procedure
• - caller passes parm's actual value
• - called proc can make changes, but caller will never recognize them
• - coller's storage is ABSOLUTELY protected from change
• .
•      Calling Procedure
• Dcl-pr Celsius Int(5);
•    *N Int(5) Value;
•    *N Char(256);  // we can mix methods
• End-pr;
• .
•      Called Procedure
• Dcl-pi Celsius Int(5);
•    Fahrenheit Int(5) Value;
•    Errmsg  Char(256);  // we can mix methods
• End-pi;

• - to pass marms by value
• - it does NOT share storage address w called procedure
• - caller passes parm's actual value
• - called proc can make changes, but caller will never recognize them
• - coller's storage is ABSOLUTELY protected from change
• .
•      Calling Procedure
• Dcl-pr Celsius Int(5);
•    *N Int(5) Value;
•    *N Char(256);  // we can mix methods
• End-pr;
• .
•      Called Procedure
• Dcl-pi Celsius Int(5);
•    Fahrenheit Int(5) Value;
•    Errmsg  Char(256);  // we can mix methods
• End-pi;

a result Ext DS to hold data

• 1) Declare file w/i declaration block
•      Dcl-f Customer;

• 2) Declaring result DS
•      - w Likerec KW

•           Dcl-ds Custdata Likerec(Custsrec);
•      - w Extname KW

          Dcl-ds Custdata Extname('CUSTOMERS':'CUSTSREC':*All);

•      - *All - fields included from Rec Format
•      - other allowed KW - *Input, *Output

• 3) Read file Customer specifying Ext DS Custdata
•      Read Customers Custdata;

• 1) Declare file w/i declaration block
• .
•      Dcl-f Wndyesno Workstn;
• .
• 2) Declaring result DS's w Likerec KW
•      - all DS's are Qualified
•      - NO End-ds b/c no additional subfields are allowed
• .
•      a) *Input for Read opcode
• .
•      Dcl-ds Windynds_I Likerec(WNDYESNOR:*Input);
• .
•      b) *Output for Write opcode
• .
•      Dcl-ds Windynds_O Likerec(WNDYESNOR:*Output);
• .
•      c) *All for Exfmt opcode
• .
•      Dcl-ds Windynds_A Likerec(WNDYESNOR:*All);
• .
• 3) To loald fields and display DSPF
• .
•      Windynds_A.F001 = '1';
•      Windynds_A.F002 = '1';
• .
•      Exfmt WNDYESNOR Windynds_A;
• .
• 4) To write to DSPF
• .
•      Windynds_O.F001 = '2';
•      Windynds_O.F002 = '3';
• .
•      Write WNDYESNOR Windynds_O;
• .
• 5) To read from DSPF
• .
•      Read WNDYESNOR Windynds_I;

• /Copy
• /Include
• - compiling directive
• - begins w (/) in position 7 or later
• - to store source records in a secondary source member (copybook)
• - copy that source into a primary source member at compile time
• - can appear anywhere in a source
• - useful for storing prototypes
• .
• This is Compiler Directives
• .
•      /Copy Mylib/Mysource,Prototypes
•      /Include Mylib/Mysource,Prototypes.
• .
• - Mylib - library (default *LIBL)
• - Mysource - source file (default *QRPGLESRC)
• - Prototypes - source member name w all reusable prototype definitions (must specify)
• .

• /Copy
•    - expanded by SQL processor
•    - /Copy program file may have its own embedded SQL code

• /Include
•    - is NOT expanded by SQL processor
•    - /Include program file CANNOT have its own embedded SQL code

• - variable or DS definitions that can be used as templates for the definition of another data items
• - can be uses only w Like or Likeds KW's
• - can be part of copybook
• .
• Dcl-ds Templ_Indicators Len(99) Template;
•    Exit           Ind Pos(3);
•    . . .
• End-ds
• .
• - Another source members that use /Copy to include the copybook code can then define a DS based on the template
• .
• Dcl-ds Indicators Likeds(Templ_Indicators);

• - /Define
•    - names a condition and adds it to a list of currently defined conditions 
• .
• - /Undefine
•    - removes the condition from the list
• .
• - /If, /Elsif, /Else, /Endif
•    - to test a condition's state
• .
• - /Eof
•    - to direct the compiler to ignore the rest of the subsequent source

• This is copybook source member 'Prototypes' w all reusable ptototype definitions
• .
•    // ----- Prototype: DayName
• .
• /If Defined(Pr_Dayname)
•    Dcl-pr DayName Char(9);
•       *N Date Value;
•    End-pr;
• /Endif
• .
•    // ----- Prototype: Dayofweek
• .
• /If Defined(Pr_Dayofweek)
•    Dcl-pr Dayofweek Packed(1:0);
•       *N Date Value;
•    End-pr;
• /Endif
• .
•    // ----- Prototype: Pr_Isweekday
• .
• /If Defined(Pr_Isweekday)
•    Dcl-pr Pr_Isweekday Ind;
•       *N Date Value;
•    End-pr;
• /Endif
• .
• In each program that uses the pocedures, add the appropriate condition name to the compiler's list of conditions
• .
• /Define Pr_Dayname
• /Define Pr_Isweekday
• /Copy MyLib/MySource,Prototypes
• .
• Only prototypes that defined under conditions Pr_Dayname and Pr_IsWeekday w/i 'Prototypes' copybook will be compiled