On Thu, Sep 29, 2016 at 10:44 PM, Martin Bjorklund <m...@tail-f.com> wrote:
> Andy Bierman <a...@yumaworks.com> 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, 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
>
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