Thanks William.
Please see below.
Regards,
Jason
> -----Original Message-----
> From: Ivory, William <[email protected]>
> Sent: Wednesday, August 8, 2018 3:27 AM
> To: Sterne, Jason (Nokia - CA/Ottawa) <[email protected]>;
> [email protected]
> Subject: Re: [netmod] false() vs 'false' in 'when' statements
>
> On 07/08/18 18:37, Sterne, Jason (Nokia - CA/Ottawa) wrote:
> Hi all,
>
> When comparing the value of a boolean leaf in a 'when' statement (or a 'must'
> statement), is an equality comparison to 'true' or 'false' the same as a check
> against true() or false() ?
>
> For example:
>
> leaf a {
> type boolean;
> }
> leaf b {
> type uint32;
> when ".../a = 'true'";
> }
> leaf c {
> type uint32;
> when ".../a = 'false'";
> }
> (note that neither b nor c can be configured if leaf a isn't explicitly
> configured
> with a value since there is no default)
>
> If I replace the two 'when' statements above with the following instead, is
> the
> behavior the same ?
> ...
> when ".../a = true()";
> ...
> when ".../a = false()";
> ...
>
> Or does "../a = true()" behave as an existence check on leaf a and would be
> enabled whether a is configured as true or false ?
>
> Regards,
> Jason
>
>
>
> See https://www.w3.org/TR/1999/REC-xpath-19991116/#booleans
>
> (a) "../a = 'true'"
>
> Compares 'string-value' (same as value of node if a leaf, rather more
> interesting if a list / container!) of each node in nodeset generated by
> '../a' and
> if any node in the nodeset matches 'true', expression is true.
[>>JTS: ] In my specific example, leaf a is a single Boolean leaf. In that
case, are these equivalent ?
when ".../a = 'true'";
when ".../a = true()";
and are these also equivalent ?
when ".../a = 'false'";
when ".../a = false()";
(sorry if I'm being dense here, but I'm not 100% positive if I'm interpreting
your explanations correctly and getting the right conclusion. I've never seen
must or when statements that use = false() or = true()).
[>>JTS: ] Are the strings 'true' and 'false' the "string-value" (that you
mention above) for a Boolean leaf ?
'a' is a single Boolean leaf so the nodeset is that single leaf and the value
is 'true' or 'false'.
>
> (b) "../a = true()"
>
> Similar to above but after getting the string-value, this is converted to a
> boolean before comparing with the boolean true.
[>>JTS: ] I'm a bit confused here. Are you saying that the string-value of
leaf a is converted to a Boolean ?
Do the string-values of a convert to something that is equal to true() or
false() ?
>
> (c) '../a'
>
> True if the nodeset generated by this expression is not empty.
>
> ---
>
> Caveats alluded to above are that if '../a' matches multiple nodes, then only
> one of these nodes needs to pass the test for the test to be true.
> Separately, if
> any of the nodes are not leaves, the 'string-value' is a concatenated string
> of
> the values of the node's child / grandchild leaves.
>
> Hope that helps. You wouldn't believe the number of unit tests I have to make
> sure we get this logic right! Using '!=' when comparing a nodeset with >1
> node
> with other values is very likely not to give the answer you expect (-:
>
> Regards,
>
> William
>
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