Andy Bierman <[email protected]> wrote:
> On Thu, Sep 29, 2016 at 10:44 PM, Martin Bjorklund <[email protected]> wrote:
>
> > Andy Bierman <[email protected]> wrote:
> > > Hi,
> > >
> > > The deviation section has a lot of fluff text about how bad deviations
> > are,
> > > but very little text on how to process the "deviate" statement correctly.
> > >
> > > The text is not clear if the statements altered in the target module
> > > are semantic patches or syntactic patches. Are the sub-statements
> > > of the deviate-stmt fully processed in the scope of the deviation module
> > > or in the scope of the target module? In this example, is the type-stmt
> > > resolved in A or dev-A?
> >
> > Deviations are not special compared to other statements; if you refer
> > to something in an external module the external module must be
> > imported and the prefixes are resolved in the module where they are
> > used. The type statement is resolved in the same way if it is defined
> > in a leaf, a typedef or in a deviate.
> >
> > So in the examples below, all variants are legal.
> >
>
> OK
>
> But it is not intuitive that the resulting type-stmt is not validated at
> all within the target
> module
Syntactically, it is evaluated in A-dev, but the result must be
semantically validated together with A. For example:
module A {
...
leaf foo {
type uint32;
}
}
module A-dev {
...
deviation /a:foo {
deviate add {
default -1; // error!
}
}
}
/martin
> , compared to some other deviations:
>
>
> module A {
> ...
> list foo {
> max-elements 3;
> ...
> }
> }
>
> module A-dev {
> ...
> deviation /a:foo {
> deviate add {
> min-elements 4;
> }
> }
> }
>
>
> The "min-elements 4" statement is valid in the A-dev module but when patched
> into list /foo it is not valid.
>
>
>
> Andy
>
>
> >
> > > Similar issues for deviating a default for an identityref.
> > >
> > >
> > > module A {
> > > namespace "...";
> > > prefix a;
> > > // no imports!
> > >
> > > leaf foo {
> > > type string;
> > > }
> > >
> > > leaf bar {
> > > type string;
> > > }
> > >
> > > leaf baz {
> > > type string;
> > > }
> > > }
> > >
> > > module A-dev {
> > > ...
> > > import A { prefix a; }
> > > import C { prefix c; }
> > > import ietf-interfaces { prefix if; }
> > >
> > > // variant 1: inline leafref but module A does not import path module
> > > deviation /a:foo {
> > > deviate replace {
> > > type leafref {
> > > base /c:modules/c:module/c:name;
> > > }
> > > }
> > > }
> > >
> > >
> > > // variant 2: imported typedef but module A does not import it
> > > deviation /a:bar {
> > > deviate replace {
> > > type if:interface-ref;
> > > }
> > > }
> > >
> > >
> > > // variant 3: local typedef but module A cannot import it (circular
> > > imports)
> > > typedef mystring {
> > > type string { length "1..10"; }
> > > }
> > >
> > > deviation /a:baz {
> > > deviate replace {
> > > type mystring;
> > > }
> > > }
> > > }
> >
> >
> >
> > /martin
> >
_______________________________________________
netmod mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/netmod
