Andy Bierman <[email protected]> wrote:
> On Mon, Nov 9, 2015 at 1:11 PM, Martin Bjorklund <[email protected]> wrote:
> 
> > Andy Bierman <[email protected]> wrote:
> > > On Mon, Nov 9, 2015 at 10:38 AM, Martin Bjorklund <[email protected]>
> > wrote:
> > >
> > > > Hi,
> > > >
> > > > I implemented most of the 1.1 features that affect the compiler in
> > > > pyang on the flight back from Yokohama.  (if you have 1.1 modules, I'd
> > > > appreciate if you could try it out).
> > > >
> > > > In doing this, I realized that I forgot one part of Y10 - "allow
> > > > restrictions on enumerations".  If we allow:
> > > >
> > > >     typedef foo2 {
> > > >       type enumeration {
> > > >         enum a;
> > > >         enum b;
> > > >       }
> > > >     }
> > > >     typedef bar2 {
> > > >       type foo2 {
> > > >         enum a;
> > > >       }
> > > >     }
> > > >
> > > > we should also allow:
> > > >
> > > >     typedef foo2 {
> > > >       type bits {
> > > >         bit a;
> > > >         bit b;
> > > >       }
> > > >     }
> > > >     typedef bar2 {
> > > >       type foo2 {
> > > >         bit a;
> > > >       }
> > > >     }
> > > >
> > > > It is briefly mentioned in the description of Y10.
> > > >
> > > >
> > > > Comments?
> > > >
> > > >
> > > Yet more complexity without any real use-cases?
> >
> > It is a matter of removing CLRs and inconsistencies.
> >
> > > How does auto-numbering work in both cases?
> > >
> > >
> > >     typedef foo2 {
> > >       type enumeration {
> > >         enum a;
> > >         enum b;
> > >       }
> > >     }
> > >
> > >     typedef foo3 {
> > >       type foo2 {
> > >         enum b;
> > >       }
> > >     }
> > >
> > >     typedef bar1 {
> > >       type enumeration {
> > >         enum b;
> > >       }
> > >     }
> > >
> > >
> > > What is the auto-numbering of enum 'b' in type foo3?
> >
> > There is none.  The text says:
> >
> >   When an existing enumeration type is restricted, the "value"
> >   statement MUST either have the same value as in the base type or not
> >   be present, in which case the value is the same as in the base type.
> >
> >
> 
> good
> 
> Is the refinement allowed to add, remove, or change if-feature-stmts?
> I don't remember seeing any text on that.

The refine statement cannot address individual enums/bits (it can only
address structure) so the answer is that it is not possible to change
if-feature on enums/bits in refinements.

> > > What value does type foo3 have over bar1?
> >
> > Unless the type has some semantics, there is none.   But when the type
> > has some semantics, the possibility to restrict an existing type is
> > useful.  If it not useful for enumerations and bits, why should we
> > have it for strings and ints, for example.
> >
> >
> 
> so the reason to do this would be to restrict the value set but
> maintain the value and position assignments.  OK



/martin

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