topic Re: Local class # Object creation from another program in Application Development and Automation Discussions

Local class # Object creation from another program

arunneerolil — Tue, 20 Feb 2018 08:06:07 GMT

Is there any way to create an object of a local class in program A in program B ?

REPORT Z_REPORT_A.
CLASS LCL_LOCAL_CLASS DEFINTION.
PUBLIC SECTION.
METHODS: say_foo.
ENDCLASS.
CLASS LCL_LOCAL_CLASS IMPLEMENTATION.
METHOD say_foo.
WRITE 'Foo from program Z_REPORT_A'.
ENDMETHOD.
ENDCLASS.

REPORT Z_REPORT_B.

Can I create an object of

LCL_LOCAL_CLASS

Z_REPORT_B

Re: Local class # Object creation from another program

Tomas_Buryanek — Tue, 20 Feb 2018 08:12:49 GMT

Not recommended! (see comments): You can put local class definition and implementation into the INCLUDE and use this include in both programs.

But it sounds it would be better to create global class? Reusability 🙂

Re: Local class # Object creation from another program

pokrakam — Tue, 20 Feb 2018 08:30:50 GMT

No you can't, the clue is in the word "Local". Use a global class.

It is however possible to use an instance of a local class elsewhere.

Also, do not use includes in multiple programs. https://help.sap.com/doc/abapdocu_751_index_htm/7.51/en-US/index.htm?file=abenmultiple_use_include_guidl.htm

Re: Local class # Object creation from another program

nomssi — Tue, 20 Feb 2018 08:46:50 GMT

Horst once said: "You shouldn't do that but you can by using absolute type names."

Re: Local class # Object creation from another program

former_member241258 — Wed, 21 Feb 2018 05:16:28 GMT

you can export/import object of class in one report to another report.

for this you have to use shared memory concept technique.

Re: Local class # Object creation from another program

arunneerolil — Wed, 18 Apr 2018 04:49:44 GMT

Is there any reason why we shouldn't use absolute type names ?

Re: Local class # Object creation from another program

retired_member — Wed, 18 Apr 2018 05:56:47 GMT

Never reuse include programs

https://help.sap.com/http.svc/rc/abapdocu_752_index_htm/7.52/en-US/index.htm?file=abenmultiple_use_include_guidl.htm

Re: Local class # Object creation from another program

matt — Wed, 18 Apr 2018 05:58:35 GMT

Yes. It's really bad programming. Likely to lead to hard to find (and therefore extremely expensive) bugs.

Why do you think you need to use local classes in this way?

Re: Local class # Object creation from another program

matt — Wed, 18 Apr 2018 06:02:02 GMT

Includes for re-use are indeed very very bad.

One project I was on decided to use an include in hundreds of BW routines. It all worked nicely until a change needed to be made... and 100s of BW flows had to be regenerated in production. Took quite a while.

The reason an include was used was the the outsourcing partner's staff weren't technically competent to do much beyond inserting include statements.

Re: Local class # Object creation from another program

retired_member — Wed, 18 Apr 2018 06:04:48 GMT

I remember a hotline issue with macros in mutliply used includes, arrgh ...

Re: Local class # Object creation from another program

Tomas_Buryanek — Wed, 18 Apr 2018 06:42:19 GMT

Edited, thank you.

It is true that I do not like debug through a lot of standard multiple used includes...

Re: Local class # Object creation from another program

nomssi — Wed, 18 Apr 2018 08:03:03 GMT

It breaks encapsulation.

If you need the functionality, that copy the class in your local scope.
If the class is too complex to copy, then you probably do not understand its contract, so how are your going to make sure it is created correctly and all its collaborators are also correctly defined?
Even if you manage to do it, the original code is by definition out of your control and can change in unexpected ways.

So, you shouldn't, but you can.

JNN

Re: Local class # Object creation from another program

Jelena_Perfiljeva — Wed, 18 Apr 2018 18:21:46 GMT

I believe this might come as a surprise to many long time ABAPers. Judging by the standard SAP code, at some point using the same INCLUDE in multiple places was The Thing. Personally, I haven't even heard that officially changed. I just happened to dislike INCLUDEs personally (especially those standard ones that tend to generate an annoying "what's the main program for this?" pop-up, ugh) and avoid them like plague. But I wouldn't have known it is a no-no these days to reuse them. Kind of thought that was their whole point... Huh. Well, that's my "learned something today". 🙂

Re: Local class # Object creation from another program

Jelena_Perfiljeva — Wed, 18 Apr 2018 18:25:31 GMT

Better question to ask would be "why do I have to have some functionality that is implemented as local?" In this case, ask "why" not "why not".

Re: Local class # Object creation from another program

retired_member — Thu, 19 Apr 2018 05:49:21 GMT

Hmm, maybe if you read the ABAP Programming Guidelines (that were also published as a book about ten years ago) from beginning to end you'll find one or the other additional rule that you didn't know of 😉

Re: Local class # Object creation from another program

matt — Thu, 19 Apr 2018 06:48:03 GMT

At one time it was considered a nice way of organising code. There were even common memory areas - take the horror of global variables to a new level!

Back in pre-2000, there was a lot of bad practice programming. I guess we just didn't know it was bad practice - or maybe it was only known inside the ivory towers of academia. Now we know what's good and bad*. One of the beneficial side effects of the internet... 🙂

* For people who can be bothered to look. Apparently, some people still use prefixes to indicate the types of their variables. 😉