[xquery-talk] why must one have something inside {} ?
David Lee
dlee at calldei.com
Sat Dec 3 15:27:00 PST 2011
I'm not suggesting "{}" is a 'no-op' I'm suggesting it parses equivalent to
{()}
Maybe in the next week or two I'll study the BNF in more detail and make a
formal suggestion as per Liam's suggestion for XQuery 3.0
So far I haven't seen any reason why it would be either
1) Ambiguous
2) Cause parser confusion
3) Cause reader confusion
4) Cause 'unexpected' things to happen
So far all the cases I can think of it would either be beneficial, closer to
what a programmer would expect and easier on the eye and hand.
Things like
element {} {}
would still be static errors just like
element {()} {()}
----------------------------------------
David A. Lee
dlee at calldei.com
http://www.xmlsh.org
-----Original Message-----
From: talk-bounces at x-query.com [mailto:talk-bounces at x-query.com] On Behalf
Of Michael Sokolov
Sent: Saturday, December 03, 2011 5:53 PM
To: David Lee
Cc: talk at x-query.com
Subject: Re: [xquery-talk] why must one have something inside {} ?
How about
element {} {}
text {}
attribute {} {}
should those be no-ops too?
I don't think so, because
element {} {"not empty"}
would be problematic
On 12/3/2011 2:41 PM, David Lee wrote:
> Yes exactly !
> Function bodies should be able to be empty too ... its so simple !
>
> declare function notimplementedyet() {};
>
>
>
> ----------------------------------------
> David A. Lee
> dlee at calldei.com
> http://www.xmlsh.org
>
>
> -----Original Message-----
> From: talk-bounces at x-query.com [mailto:talk-bounces at x-query.com] On Behalf
> Of Michael Dyck
> Sent: Saturday, December 03, 2011 2:28 PM
> To: talk at x-query.com
> Subject: Re: [xquery-talk] why must one have something inside {} ?
>
>
> David Lee wrote:
>> I am asking why in *XQuery* the expression {} is not equivalent to {()}
> It might simply be that no-one suggested it.
>
>> Is there a case in *XQuery* where this would be problematic ?
> I don't think so.
>
> Probably the least-impact way for the spec to accomplish this would be
> to alter the syntax of EnclosedExpr, from
> EnclosedExpr ::= "{" Expr "}"
> to
> EnclosedExpr ::= "{" Expr? "}"
> and then say that, if the Expr is omitted, the EnclosedExpr yields the
> empty sequence. Note that, in addition to element and attribute content,
> this would also take effect when an EnclosedExpr is used as a function
> body, which may or may not be something you'd like as well.
>
> -Michael
>
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