Andy Bierman <[email protected]> wrote:
> Hi,
>
> The ABNF for "default" is wrong in the deviate-*-stmt (add, replace, delete)
> Is says [default-stmt] but it should be *default-stmt
Thanks, fixed.
But for deviate-replace, it is not clear what the correct answer is.
This is pretty clear:
leaf foo {
type int32;
default 42;
}
deviation /foo {
deviate replace {
default 10;
}
}
But what about this:
leaf-list bar {
type int32;
default 42;
default 43;
}
deviation /bar {
deviate replace {
default 10;
default 11;
}
}
Are all defaults changed?
Compare with must and unique - they can not be replaced currently.
In order to resolve this we probably need more text as well :(
OLD:
The argument "replace" replaces properties of the target node. The
properties to replace are identified by substatements to the
"deviate" statement. The properties to replace MUST exist in the
target node.
NEW:
The argument "replace" replaces properties of the target node. The
properties to replace are identified by substatements to the
"deviate" statement. The properties to replace MUST exist in the
target node. If multiple properties exist in the target node, all
of them are replaced with the new properties defined in the
substatements to the deviate statement.
+ add an example to the section "Usage examples":
NEW:
In this example, the original definition of a leaf list has two
default values "42" and "43:
leaf-list bar {
type int32;
default 42;
default 43;
}
A server can change this to the values "10" and "11" instead:
deviation /base:bar {
deviate replace {
default 10;
default 11;
}
}
Also, change the grammar:
OLD:
deviate-replace-stmt = deviate-keyword sep replace-keyword-str optsep
(";" /
"{" stmtsep
;; these stmts can appear in any order
[type-stmt]
[units-stmt]
[default-stmt]
[config-stmt]
[mandatory-stmt]
[min-elements-stmt]
[max-elements-stmt]
"}") stmtsep
NEW:
deviate-replace-stmt = deviate-keyword sep replace-keyword-str optsep
(";" /
"{" stmtsep
;; these stmts can appear in any order
[type-stmt]
[units-stmt]
*must-stmt
*unique-stmt
*default-stmt
[config-stmt]
[mandatory-stmt]
[min-elements-stmt]
[max-elements-stmt]
"}") stmtsep
> Is it intentional that the ABNF for deviate-delete-stmt leaves out
> config, mandatory, max-elements, and min-elements?
> I understand why "type" cannot be removed.
I don't really remember, but I can see that if you want to "delete"
min-elements you can replace it and set it to 0.
> IMO the rest of the statements should be removable.
> Sec. 7.20.3.2 does not mention the restrictions indicated in the ABNF.
> This section should make it clear a leaf has only 1 default
> and the 0..n refers to leaf-list only.
In general, the result after applying deviations must be valid - e.g.,
you cannot deviate "foo" as the default for an int32 leaf.
> It should also be clear that the "deviate add default" for a leaf-list
> is YANG statement order-dependent.
>
> Not as obvious -- a config=false leaf-list can have duplicate default
> values.
> The deviate-stmt has no way to specify which 1 to delete or replace
> if there are duplicates.
Unless replace will replace *all*, as suggested above.
/martin
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