In this tutorial you will learn:

SAP- ABAP Macro Include Programs Subroutines Function Modules Function Groups

Need of Modularization

Improve the structure of the program. Easy to read the code Easy to maintain the code Avoid redundancy and promotes code reuse

Various Modularization Techniques

Use of Macros Use of include files Subroutines Function Modules

Lets look into each of them in detail :

SAP- ABAP Macro

If you want to reuse the same set of statements more than once in a program, you can include them in a macro. You can only use a macro within the program in which it is defined, and it can only be called in lines of the program following its definition. Macros can be useful for long calculations or complex WRITE statements. Syntax Macros can use Parameters &N where N = 1,2,3… Example:- Output: 2

Include Programs

Include Programs are solely for modularizing source code, and have no parameter interface. Include programs allow you to use the same source code in different programs. They can be useful if you have lengthy data declarations that you want to use in different programs. Syntax Points to Note

Include programs cannot call themselves. Include programs must contain complete statements.

Example:

Subroutines

Subroutines are procedures that you can define in any ABAP program and also call from any program. Subroutines are normally called internally, that is, they contain sections of code or algorithms that are used frequently locally. If you want a function to be reusable throughout the system, use a function module. Syntax- = Name of the subroutine = Parameters being passed Types of Subroutines

Internal

Subroutine defined in same program being called. Can access all the data objects declared in the main ABAP/4 program.

External

Subroutine defined outside the program being called. Need to use the option or declare data objects in common parts of memory.

Calling a Subroutine Internal Subroutines = Name of the subroutine = Parameters being passed Data declared in main program is automatically available. External Subroutines Points to Note

Nested calls are allowed in subroutines (i.e. PERFORM within a FORM … ENDFORM ). Recursive calls are also possible. To define local data, use the DATA statement after FORM . Each time you enter the subroutine, the data is recreated (with an initial value) and released at the end (from the stack). To define global data used within a subroutine, use the LOCAL statement after FORM . The values are saved when you enter the subroutine and then released at the end (from the stack)

Function Modules

Function Modules are general purpose ABAP/4 routines that anyone can use. Infact , there are a large number of standard function Modules available. Function Modules are organized into Function Groups: Collections of logically related functions. A Function module always belongs to a Function Group. Syntax- Important information Associated with Function Module

Administration Import/Changing/Export parameters. Table Parameters/Exceptions. Documentation Source code – LU01 . is the Function Group Global Data – LTOP .Global data for the function group- Accessible across function modules in the function group. Main Program – SAPL . Contains the list of all the include files for that function group

Call a Function Module To call a function module, use the CALL FUNCTION statement:

Function Groups

Function groups are containers for function modules. Infact, there are a large number of standard Function Groups. All of the function modules in a function group can access the global data of the group. Like executable programs (type 1) and module pools (type M), function groups can contain screens, selection screens, and lists. Points to Note

Function Groups cannot be executed. The name of a function group can be up to 26 characters long. When you create a function group or function module, the main program and include programs are generated automatically. Function groups encapsulate data.

How to create a Function Group

Goto Transaction SE80. Select Program in the DropDown. Write the name of the Function Group That you want to create. Generally User made Function groups start with “Z”. e.g. – <Z_FUNCTION_GROUP_NAME> . Hit Enter Key. Note that The TOP Include is create by default if the user checks the option of creating a TOP include.

How to create a Function Module

Create a function Group (say “ZCAL“). Create a function module, set the attributes like (Function group, Application, Short Text and Process Type) and Save. Include file “LZCALU01” will have source code of first function module. Include file “LZCALTOP” will have global data. Main program “SAPLZCAL” contains

Global data Include file “LZCALTOP“ Function modules include file “LZCALUXX“ User defined Include files “LZCALF..”, “LZCALO..” and “LZCALI..”

Define interface parameters and Exceptions Write the source code Activate Function Module Testing the Function Module – Single Test & Debugging Documenting and Releasing a Function Module

That’s all to Modularity in ABAP.