topic Re: recursive structure: compiler error in Application Development and Automation Discussions

recursive structure: compiler error

hubert_heitzer — Tue, 17 Apr 2018 12:34:35 GMT

Hi,

I'd like to define a recursive structure like

TYPES:
  BEGIN OF st_assembly_element,
    matnr TYPE                   matnr,
    brkup TYPE                   c,
    state TYPE                   icon_d,
    " ...
    pords TYPE STANDARD TABLE OF ebeln               WITH DEFAULT KEY,
    elems TYPE STANDARD TABLE OF st_assembly_element WITH DEFAULT KEY,
  END OF st_assembly_element
.

Compiling this code leads to an "unknown type: st_assembly_element"-error.

Is there a way of forward declaration in ABAP (syntax required)?

How can I avoid this error (without using TYPE REF TO data)?

Regards,

Hubert

Re: recursive structure: compiler error

pokrakam — Tue, 17 Apr 2018 14:52:27 GMT

Even if the compiler allowed it, I would not do it.

You couldn't read it properly without some kind of dynamic referencing. And if we're going to do that then a hierarchical list is much easier to code, understand, and debug. If you want recursion, use objects; much neater.

Re: recursive structure: compiler error

UweFetzer_se38 — Tue, 17 Apr 2018 15:05:00 GMT

The "elems" should be just STANDARD TABLE of matnr in my opinion because this i the key for the next layer.

(standard in Bill of Materials [BOM])

Re: recursive structure: compiler error

hubert_heitzer — Wed, 18 Apr 2018 07:29:33 GMT

Of course can I read it properly without some kind of dynamic referencing.

I need this data structure only in this special case, so I try to avoid the overhead of OO.

Re: recursive structure: compiler error

pokrakam — Wed, 18 Apr 2018 07:38:24 GMT

Sorry, bad phrasing. I meant dynamic processing or referencing. You will need some kind of looping or nested access methods.

I don't see OO as being significant overhead. Clarity / ease of use is a good tradeoff for a really minor performance hit. To me this screams out for OO 🙂