Variadic Functions in ABAP?

[thomas_bonk]

Hello,

is it possible to define variadic method sin ABAP-OO?

Thanks & Best regards,

Thomas

[Former Member]

Hi, Thomas!

I don't think it is possible in a way it is done in C, for example.

Depending on your needs you can mark some arguments as optional (but you'll have to define them).

If it's not enough, maybe sending some table of input parameters (e.g., name, type, value) will help you. But I don't think it's a nice solution Maybe community gurus can advise a more elegant way of accomplishing your task.

[matt]

I've used optional parameters when I've needed that kind of functionality.

[ceedee666]

Hi Matthew,

the difference between variadic functions or methods and optional parameters is, that you have do define the optional parameters beforehand. I contrast to that, variadic functions enable you to provide additional parameters without specifying how many optional parameters could occur during the definition of the function or method.

I think Nikolay is right, there is no elegant solution for variadic functions in ABAP. 

Christian

[matt]

The nearest then will be internal tables. But I'd probably implement them as just another class. Do you have a particular scenario in mind? (I extensively program in other languages that do have variadic functions and have so far never actually needed them!).

[ceedee666]

Hi Matthew,

yes, I think an optional internal table could be a good substitute in many situations.

IMHO you would mostly need variadic functions if you try to build some kind of framework. The most natural candidates for variadic functions I can thinks of are e.g. concat, min or max. These are implemented in Clojure as variadic functions.

For some of these (concatenate) there are build in language constructs in ABAP. To implement min or max you would most likely use an internal table to provide the arguments.

Christian

[matt]

I'm not certain of the syntax, but for a max function, something like this would probably work (in 7.40)

If I have i,j and k, all integers, and I want the max, I can create a method max, that takes an internal table of integers as importing parameter (and returns the max). I can then call max like this:

data(maximum) = my_class->max( VALUE #( ( i ) ( j ) ( k ) ).

[ceedee666]

Hi Matthew,

interesting idea. This way one at least doesn't need to create additional auxiliary variables (at least not explicitly). I'll give it a try.

However, the problem I see with this approach is that I always have to provide the additional constructor expression when invoking the method.

Christian

[matt]

I wonder if as any ideas! 🙂

[Former Member]

Yeah, Horst is extremely welcome in this thread 😉

[retired_member]

nmax, nmin are other built-in functions.

[ceedee666]

Hi Horst,

But even nmax and nmin are not variadic, right? They only allow for up to 9 arguments. If I'd like to have a function that also works with 10 or 11 parameters I'd have to use a different approach.

I guess the real question is if there is an idiomatic approch in ABAP (e.g. with some of the features in 7.40) that allows the creation of variadic functions or methods.

Christian

[retired_member]

if there is an idiomatic approch in ABAP (e.g. with some of the features in 7.40) that allows the creation of variadic functions or methods

Sorry, none that I know of. Only the means of generic/dynamic programming discussed already here.