Re: [netmod] [yang-doctors] Recursive extensions?

[Martin Bjorklund <[e-mail]>]

Andy Bierman <[e-mail]> wrote:
> On Mon, Oct 17, 2016 at 2:01 PM, Nadeau Thomas <[e-mail]>
> wrote:
> 
> >
> >         Adding Yang Doctors to the thread.
> >
> >         —Tom
> >
> >
> > > On Oct 17, 2016:4:42 PM, at 4:42 PM, Robert Varga <[e-mail]> wrote:
> > >
> > > Hello everyone,
> > >
> > > neither RFC6020 nor RFC7950 seem to be explicit about this, so I thought
> > > I'd ask.
> > >
> > > Are recursive, directly or transitively, extensions valid yang?
> > >
> >
> 
> 
> Extensions are not recursive.
> Your syntax below is valid but not meaningful.

Here's a real (and meaningful) example of a "recursive" extension:

  extension substatement {
    argument name {
      tailf:arg-type {
        type string;
      }
    }
    tailf:use-in "extension";
    tailf:occurence "*";

    tailf:substatement "tailf:occurence";  // <-- reference to self
    description
      "Specifies which statements can occur as substatement to the
      given statement.";
  }

This is not different from how the core YANG statements can be used;
e.g., you can use "container" within "container".



/martin