topic Re: function module and perform in Application Development and Automation Discussions

function module and perform

Former Member — Tue, 12 Feb 2008 16:19:48 GMT

What is the main difference between function module and perform?

Re: function module and perform

Former Member — Tue, 12 Feb 2008 16:26:38 GMT

The main difference between a function module and a normal ABAP/4 subroutine is as follows:

Function is stored in central library and has global presence while subroutines are confined to a particular program. Subroutine cannot return values while functions can return values. Unlike functions, subroutine cannot handle exceptions. And last but not least, the difference in the way the parameters are passed to functions.

Declaring data as common parts is not possible for function modules. The calling program and the called function module have separate work in ABAP/4 Dictionary tables.

You use the ABAP/4 Workbench to call, create, and maintain function modules.

You can combine several function modules to form a function group in the function library. Since you can define global data that can be accessed from all function modules of one function group, it is reasonable to include function modules that operate with the same data, for example internal table for sales module can be grouped, in one function group.

Re: function module and perform

former_member156446 — Tue, 12 Feb 2008 16:28:51 GMT

perform can be called from other programs , FM can also be called in any program...

FM have function group... perform doesn't have...

exceptions can be handled in FM... in performs we cant..

Re: function module and perform

Former Member — Tue, 12 Feb 2008 16:45:41 GMT

good

Here is the notes of differences bet. FM and Subroutines.

Hi Function modules are for modularization urpose. You can the Function Module in any program. That is available all over in the SAP system.

Where as subroutine is program specific. Once you create a subroutine in one program then you can use that in that program and related programs like includes in the program or you have to call the subroutine specifically using the main program name.

Finally subroutines are for program modularization. Not for generic use.

FM's are for generic use. Not program dependent.

FMs are mainly used when a routine is to be performed by many programs.

Subroutines (forms) are generally only executed within one program.

You can perform routines from other programs, but it's not often done.

both forms and FMs are reusable modularization units.

To distinguish we generally say that forms are used for internal modularization and

FMs are used for external modularization.

To decide on which to implement, consider whether you need the content to be used just for a limited program

or wheteher it can be called from many independent programs.

For the first purpose it is better to implement a form whereas for the second we implement an FM.

However, ABAP does not isolate the usage context.

That is; you can call a form from another program within whose code the form is not actually implemented.

However, this requires attention since the form may utilize global variables.

The same issue holds for FMs.

FMs are encapsulated in function groups and function groups may have global variables that can be globally

used by all FMs inside it.

thanks

mrutyun^

Re: function module and perform

Former Member — Tue, 12 Feb 2008 18:12:30 GMT

Sub routines :

1. Sub routines doesn't return any values.

2. Sub routines in one R/3 can't be accessed by another R/3 systems.

3. Sub routines for local programs and current client only.

Function modules :

1. Function modules are global for all programd and all clients.

2. Function modules are accessed by same R/3 another R/3 and non R/3 systems also.

3. Function modules should return a value(more than one also)

4. Function modules are used at Module pool programs, BDCs, Scripts and smart forms.