I've got a couple of questions about the interaction of "uses" and
"augment". I hope that these have straightforward answers that the old
hands can tell me easily enough.
1. Augmenting a grouping
I notice that "augment" is not allowed to target a "grouping", despite
that naively seems to be an operation that a module designer might like
to do. I expect that there is a reason why this is not allowed.
For example:
module foo {
...
grouping target {
leaf address {
type inet:ip-address;
description "Target IP address.";
}
leaf port {
type inet:port-number;
description "Target port number.";
}
}
}
module bar {
...
import foo {
...
}
augment "/foo:target" {
leaf new-leaf {
type string;
}
}
}
module baz {
...
import foo {
...
}
container main {
uses foo:target;
}
}
giving an effective schema:
container main {
leaf address {
type inet:ip-address;
description "Target IP address.";
}
leaf port {
type inet:port-number;
description "Target port number.";
}
leaf new-leaf {
type string;
}
}
This construct seems to be well-defined to me, other than that it's not
immediately clear what namespace baz:main/new-leaf is in. (For some
reason, I reflexively think that it's in bar's namespace, not baz's, but
I can't state any reasoning for that.)
2. "augment" as a substatement of "uses"
In section 7.17:
The "augment" statement allows a module or submodule ... to add to
the nodes from a grouping in a "uses" statement.
When I first read this, I took it to mean that an "augment" substatement
adds a peer node to the set of nodes 'from a grouping in a "uses"
statement'. But I suspect that it is intended to mean that an "augment"
only adds nodes *under* one of the nodes from the grouping. There's an
ambiguity that could be fixed by better wording.
7.17 also says:
If the "augment" statement is a substatement to the
"uses" statement, the descendant form (defined by the rule
"descendant-schema-nodeid" in Section 14) MUST be used.
My understanding is that "descendant-schema-nodeid" is an XPath
expression, and that the "context node" for its evaluation is the node
to which the "uses" statement adds nodes -- but that doesn't seem to be
stated anywhere.
(Those last two I should have caught in my Gen-ART review!)
Thanks for any information,
Dale
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