On 25/02/16 22:08, John Bollinger wrote:
On Thursday, February 25, 2016 at 8:55:01 AM UTC-6, Trevor Vaughan wrote:
Hmm.....
I think, as long as it is documented, then whatever behavior is
deterministic is fine.
'
I think that there is value in the following resolutions:
Notify['left'] -> [] -> Notify['right']
* Noop since there is nothing in []
Notify['left'] -> [] -> Notify['right']
Notify['left'] -> Notify['right']
* First == Noop
* Second == Expected ordering
I flip-flopped a bit on this. I started from the position that it would
be inappropriate for
|
Notify['left']->$stuff ->Notify['right']
|
or
|
Notify['left']->Stuff<||>->Notify['right']
|
ever to fail to cause Notify['left'] to be applied before
Notify['right'], as indeed it now does fail to do in the event that the
stuff in the middle represents zero resources. My basis there was that
it is counterintuitive for such expressions to not establish relative
ordering of the two Notifys.
Ultimately, however, that basis is completely subjective. Others might
reasonably intuit that such an expression would have exactly the
semantics it actually does have, which are roughly equivalent to those of
|
Notify['left']->$stuff
$stuff ->Notify['right']
|
. Upon reflection, this alternative is less magic. It falls out
naturally from understanding that chain operators associate from left to
right, and that each binary chain expression /evaluates to/ the value of
its right-hand operand. That some people might find that behavior
surprising is a consideration, but not a primary one for me.
It depends on the operator if it is left or right associative and if it
is cumulative. And also what the result of '(nothing) op (something)'
results in.
if
(nothing) -> X
X -> (nothing)
both evaluate to X
as in
0 + 1
1 + 0
Then empty man in the middle would be a noop.
If you consider the arrows to abstractly order a set of resources in an
array which at the end of the chain defines the partial order of the
resources it would be the same as doing array concatenation.
i.e.
[A] + [] + [B] = [A, B]
So - it is all down to definition of the arrow operators; i.e.
taste/most practical/least surprise.
- henrik
--
Visit my Blog "Puppet on the Edge"
http://puppet-on-the-edge.blogspot.se/
--
You received this message because you are subscribed to the Google Groups "Puppet
Developers" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to puppet-dev+unsubscr...@googlegroups.com.
To view this discussion on the web visit
https://groups.google.com/d/msgid/puppet-dev/56CF80DD.7010200%40puppetlabs.com.
For more options, visit https://groups.google.com/d/optout.
