From: Noel Winstanley <Noel.Winstanley-at-manchester.ac.uk>
Subject: Re: ADQL WD v1.05
Date: Tue, 4 Jul 2006 00:05:44 +0200
> Hi,
> Here's some comments, on comments.
>
> page 6 -
> "Comments SHALL be supported using the /* ... */ syntax to delimit
> comments.
> Comments are only supported before and after the main query. "
>
> Not allowing comments within queries is counter-intuitive and reduces
> their usefulness. The accepted model for comments in programming or
> query languages is that they may occur anywhere. The syntax of a
> comment is usually defined at the lexographical level, so that they
> don't form a part of the BNF grammar of the language.
>
> Once comments are included in the BNF, where they occur is
> necessarily limited. I can only think that this has been done because
> you wish to preserve comment information in the translation from adql/
> s to adql/x (probably a good idea), and so define an xml tag to
> represent a comment? (I can't verify this, as the link from this
> document to the associated xml schema is broken )
Yes.
> If this is the case, I don't think using an xml tag to model a
> comment is the correct approach - a processing instruction would be
> more suitable, as it then does not occur in the XSD schema, and can
> be placed anywhere within the adql/x version of the query without
> complicating the schema.
I see, you are proposing to insert something like this:
<?adql comment="comment string"?>
OK. It looks good.
Is it possible to handle the processing instruction by an XML parser ?
> According to Elliot Rusty Harold's book (can't find reference at the
> moment), this is an acceptable use of a processing instruction.
>
>
> ---
>
> BTW I think the adql/x schema should be inline as an appendix in the
> final version of this document - as well as a stand-alone xsd file -
> as defining this is just as important as defining the adql/s
> presentation of the language.
OK. I will do.
Yuji. Received on 2006-07-04Z09:16:29