ietf-nntp Wildmats

[Charles Lindsey]

In <20010313110454.N93716 at demon.net> "Clive D.W. Feather" <clive at demon.net> writes:


>Charles Lindsey said:

>> Hmm! I would prefer disallowing it. But if the consensus was otherwise,
>> then I suppose consistency is a good thing. Would it be possible to say
>> that [d-a] was allowed syntactically, but would never match anything. In
>> that case it would still happen that "[d-a],[^d-a]" would match
>> everything.

>I think you misunderstand me. The consensus from last time was that "[d-a]"
>would match exactly one character. That is, there exists a legitimate set
>that it's equivalent to.

Exactly so. I was merely suggesting that the "legitimate set" should be
defined to be the empty set.

>I'd like opinions (not just yours) on the following choices:

>(1) Within a set, "d-a" is ignored. This means that:
>    * "[d-a]" never matches anything
>    * "[^d-a]" is equivalent to "?"
>    * "[d-ax-z]" is equivalent to "[x-z]"
>    * "[^d-ax-z]" is equivalent to "[^x-z]"
>(2) Within a set, "d-a" is converted by the implementation to some
>    (legal) set (not necessarily a range), converting it the same way
>    each time. This means that:
>    * "[d-a]", "[d-ad-a]", and "[d-a],[d-a]" all match the same set
>    * "[d-a],[^d-a]" matches every possible one-character string
>    * nothing matches both "[d-a]" and "[^d-a]"
>    * "[d-ax-z],[^d-ax-z]" also matches every possible one-character string
>    * nothing matches both "[d-ax-z]" and "[^d-ax-z]"
>    * "[d-ax-z]" definitely matches "x", "y", and "z"
>(3) Within a set, "d-a" causes the entire set contents (including the "^")
>    to be replaced by an arbitrary set of characters that may differ each
>    time it occurs. This means that:
>    * "[d-a]", "[d-ad-a]", and "[d-a],[d-a]" might all match different sets
>    * "[d-a],[^d-a]" might not match some one-character strings
>    * something could match both "[d-a]" and "[^d-a]"
>    * "[d-ax-z]" might not match "x"

I prefer (1), then (2).

-- 
Charles H. Lindsey ---------At Home, doing my own thing------------------------
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