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Re: [sieve] draft-ietf-sieve-external-lists

2010-09-29 09:28:55
On 9/29/10 12:38 AM, Barry Leiba wrote:
Section 2.2 states:

  The external lists are queried, perhaps
  through a list-specific mechanism, and the test evaluates to "true"
  if any of the specified values matches any member of one or more of
  the lists.

And:

  When any value is found to belong to the
  list, the queries stop and the test returns "true".  If no value
  belongs to the list, the test returns "false".

If a test MUST return true if any value is found to belong to the list,
does that place a limit on the "list-specific mechanism" by which a list
can be queried? If so, it would be good to say that, and to describe a
bit more what we mean by list-specific mechanisms. (It's also not clear
to me how such list-specific mechanisms are discovered or advertised.)

There's no reason for it to be either discovered or advertised.  The
point of talking about a "list-specific mechanism" is exactly that
it's opaque, so no assumptions can be made about how it works.  It's
not done with a Sieve comparison.

The "queries stop" bit was meant as a way to say that once a match is
found, the list-specific mechanism needn't keep looking at the other
values.  If you think it's useful, I can change the text to say that.
Perhaps:

    If any value is found to belong to the list, the test returns
"true".  If no value
    belongs to the list, the test returns "false".  Once a value is
found in the list,
    there is no need for the query mechanism to look further.

I think that's better. Off the top of my head I can't come up with a
list-specific mechanism that might continue processing after finding a
match, but that seems like a matter of implementation and not something
that needs a MUST in the spec.

IMHO it would be helpful for Section 2.5 to provide more examples.

More examples are always good.  If anyone can give me specific
examples, I'll put them in.  Unless there are implementations of this,
I don't know that we have good examples to give.

Sorry, I don't have examples to give, but the title of that section is
"Examples" so I was hoping for more than one. ;-)

Section 4 mentions both the ':list' match type and the ':list' argument
for the 'redirect' action. Are there (or could there be) any other uses
for the extlists extension?

There aren't any we've thought of.  Do you have anything in mind?
I suppose one could come up with a use case for having the target of
"fileinto" come from a list, or something like that.  But (1) no one's
seen a need for that yet, and (2) it's always possible to extend this
extension in future.

I do think it would be helpful to say somewhere (perhaps in Section 2 or
2.1) that the use cases in this document are not exhaustive and that the
extlists capability could be used for other Sieve features in the future.

Peter

-- 
Peter Saint-Andre
https://stpeter.im/


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