Re: I-D Action: draft-ietf-sieve-include-07.txt

On Sat, Jul 9, 2011 at 8:42 AM, Alexey Melnikov
<[email protected]> wrote:
> Barry Leiba wrote:
>
>>>>> ## 'ISSUE' 3:
>>>>>
>>>>> I've had a few request and questions from users about having an
>>>>> optional
>>>>> include, i.e. an include directive that is skipped without error if
>>>>> (and
>>>>> only if) the to-be-included script does not exist. Do you find this a
>>>>> useful
>>>>> feature? If yes, is it possible to add this to the main draft now or
>>>>> should
>>>>> there be an 'include-optional' extension that adds an ':optional' tag
>>>>> to
>>>>> the
>>>>> include command?
>>>>>
>>>>
>>>> Oh, huh. I suppose at least a hack around this would be an empty script?
>>>>
>>>
>>> Yes, but that will not be adequate in many situations. Do more people
>>> have
>>> thoughts on this?
>>>
>>
>> I would support an ":optional" tag on "include", which would cause an
>> error NOT to be generated if the included script doesn't exist.  That
>> should be an easy change to the text, and an easy thing for
>> implementors to do.
>>
>
> +1. I would like to see this being added as well.

Here's the language I came up with, and updated ABNF. I realized that
the way the ABNF was currently written, the tagged parameters to
include had a specific order. I don't think this was intentional, but
was just an artifact of there having been only one parameter when the
ABNF was first written.

=== OLD ===

3.2.  Control Structure include

         Usage:   include [LOCATION] [ONCE] <value: string>
               LOCATION = ":personal" / ":global"
               ONCE = ":once"

...

   The "location" parameter MUST default to ":personal" if not
   specified.  The "location" has the following meanings:

=== NEW ===

3.2.  Control Structure include

         Usage:   include *[PARAMETERS] <value: string>
                       PARAMETERS = LOCATION / :once / :optional
                       LOCATION = :personal / :global
...

   The "location" parameter MUST default to ":personal" if not
   specified.  The "location" parameter MUST NOT be specified more than
   once.  The "location" has the following meanings:

...

   The ":optional" parameter indicates that the script may be missing.
   Ordinarily, an implementation MUST generate an error at runtime if an
   include command specifies a script that does not exist.  When
   ":optional" is specified, implementations MUST NOT generate an error
   for a missing script, and MUST continue as if the include command had
   not been present.


I realize that the new ABNF allows more than one location parameter to
by syntactically valid, so I added text that it cannot be specified
more than once. I hope that's reasonable; if not, better ABNF is
welcome.

Given that the pre-meeting embargo begins at 17:00 Pacific time on
Monday (tomorrow), I'm going to post the text above now, and we can
discuss the details during the week.

Cheers,
Aaron
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