topic Re: Delete instance of singleton class in Application Development and Automation Discussions

Delete instance of singleton class

mahesh_jagnani — Thu, 08 Jul 2021 06:40:25 GMT

Hello All,

I have a requirement where i need to create instance of singleton class and after that delete it and recreate instance which another parameter.

can you please suggest how i can do that.

thanks

Re: Delete instance of singleton class

FredericGirod — Thu, 08 Jul 2021 06:57:05 GMT

First thing, you cannot delete an instance in ABAP (for human abaper)

So your only solution is to clear the "variable" containing the reference to the instance.

and it depends of your code, but it is certainly available in the my_class=>get_instance( ).

(you have to create my_class=>delete_instance)

just a question, why do you use singleton if you clear the instance after use it ??

Re: Delete instance of singleton class

matt — Thu, 08 Jul 2021 07:20:17 GMT

If you need to delete the instance, then it shouldn't be a singleton class.

Re: Delete instance of singleton class

BiberM — Thu, 08 Jul 2021 07:33:50 GMT

Maybe the singleton as you implemented it is the wrong solution.

Is there the requirement to delete an instance and recreate with the SAME parameters?

My idea is to keep one instance per parameter combination.

But: if you don't need the instance any more at all you should not buffer it.

Re: Delete instance of singleton class

mahesh_jagnani — Thu, 08 Jul 2021 07:35:54 GMT

Hello,

i want to create instance with different parameters but not able to do that as it is saying instance is already created.

Thanks

Mahesh

Re: Delete instance of singleton class

FredericGirod — Thu, 08 Jul 2021 08:26:22 GMT

So you need to convert your Singleton to MultiTon

Re: Delete instance of singleton class

FredericGirod — Thu, 08 Jul 2021 08:58:39 GMT

raymond.giuseppi his requirement is to have a singleton depending of parameters, so it could be a multiton

Re: Delete instance of singleton class

RaymondGiuseppi — Thu, 08 Jul 2021 09:07:42 GMT

Sorry, but your requirement is at least paradoxical (does not really make sense)

Is this a standad class or a customer one, in second case convert it to a normal class (with non private constructor)

Re: Delete instance of singleton class

RaymondGiuseppi — Thu, 08 Jul 2021 09:10:05 GMT

Read some documents such as

Re: Delete instance of singleton class

RaymondGiuseppi — Thu, 08 Jul 2021 09:11:56 GMT

frdric.girod multiton is useful for performance, reusability, if OP doesn't use same parameter twice, I would rather suggest a classic standard class.

Re: Delete instance of singleton class

matt — Thu, 08 Jul 2021 09:41:12 GMT

Clean ABAP suggests only using singletons when you really need them. I used to use them a lot, but they're not usually necessary in ABAP.

Re: Delete instance of singleton class

FredericGirod — Thu, 08 Jul 2021 11:18:33 GMT

I use them a lot for User-exit.

And I think in Clean-Pattern-Code you should use factory to manage the Multi or Single ton

Re: Delete instance of singleton class

FredericGirod — Thu, 08 Jul 2021 11:22:30 GMT

raymond.giuseppi I am not agree with you.

Last time I used the multitone was for item in sales order in several user-exit / enhancement / badi ... (big big project). Each item need to have separated memory / behaviour. This is not related to performance.