Re: [sieve] Question about draft-ietf-sieve-external-lists-02

[Alexey Melnikov <[e-mail]>]

Jeffrey Hutzelman wrote:
> --On Tuesday, August 03, 2010 10:34:46 AM +0200 Stephan Bosch 
> <[e-mail]> wrote:
>>> There's also the possibility of doing something akin to how the
>>> current regex
>>> draft uses comparators - as a means of identifying a canonicalization
>>> and what
>>> constitutes a unit of comparison. Do we want to allow that sort of use
>>> with
>>> :list?
>> Hmm, well.... why not? I suggest we make it an error only when the list
>> has no explicit use for it, meaning that implementors MAY accept
>> comparators for an external list, but MUST trigger an error when the 
>> list
>> does not use the specified comparator or the comparator is incompatible
>> somehow.
>>
>> I guess the main question is: what would be the disadvantage of 
>> providing
>> more flexibility to the implementor for the interaction of :list with
>> comparators?
> This sounds like an interoperability nightmare.  You describe a 
> situation where a SIEVE implementation has the option to accept 
> comparators or not, but if not, then providing them is an error, and 
> there is no way for the producer of the sieve script to know in 
> advance what will happen.
>
> This is _not_ analogous to comparators that work with :is but not with 
> :matches or :contains, because you can know from the specifications 
> which combinations are acceptable and which will produce errors.
Good point. Before I saw your message Stephan almost got me convinced 
otherwise.