restrict yang leafref key identifier without extra leaf - ietf-netmod-yang

Question

I have a yang model with a leafref, which is pointing to a list inside of a other list.
Basically something like this:
list some-names
{
key "name";
leaf name
{
type string;
}
list some-other-names
{
key "name";
leaf name
{
type string;
}
}
}
I want to point from outside with a leafref to the some-other-names list but only the ones with upper name equals to foo.
Unfortunately the leafref has to have a current() for restriction.
So my current solution is the following but requires a extra leaf which
is total unnecessary for configuration .
leaf foo
{
type string;
deafault "foo";
}
leaf some-leaf-ref
{
type leafref
{
path "/some-names[name = current()/../foo]/some-other-names/name";
}
}
Is there a simpler way than this, which does not need a additional leaf for restricting the name of some-names to a certain value?
BTW this I already tried but its not a correct path-arg:
leaf some-leaf-ref
{
type leafref
{
path "/some-names[name = 'foo']/some-other-names";
}
}

Answer 1

Perhaps something along the lines of:
leaf some-leafref {
must "/some-names[name = 'foo']/some-other-names/name = .";
type leafref {
path "/some-names/some-other-names/name";
}
}
So, no predicate in the path expression, yet with an additional must restriction - the two expressions are essentially ANDed together. YANG specification does mention that a path expression may evaluate to a node set that contains more than one node, and it doesn't say predicates are mandatory per key (unlike for instance-identifiers). Seems like hackery to me, though, or ugly at least.
Perhaps what you really want is a leafref leaf child to your outer list (some-names), that has a when to make it valid only when ../name = 'foo'.
list some-names {
key "name";
leaf name {
type string;
}
list some-other-names {
key "name";
leaf name {
type my-type;
}
}
leaf some-leafref {
when "../name = 'foo'";
type leafref {
path "../some-other-names/name";
}
}
}