Sorry, I think I neglected to include a let before a couple of the
returns. But my main point was the unusual (and probably unfamiliar to
people used to other languages) change in the interpretation of
parentheses when they follow the return keyword and when they follow the
return function.
Admittedly the idea of defining a function with the same name as a
keyword is contrived and ill-advised, right up there with C++ operator
overloading. It just occurred to me on reading Michael Kay's comment
'There is no function called "return"' that there actually could be one.
Mike Sokolov
On 10/1/2012 8:55 PM, Ronald Bourret wrote:
This is actually very straightforward. "return" is a keyword, used in
FLWOR expressions and a few other places. There is no standalone
"return" in XQuery. Thus:
let $x:=0 return (23)
is a valid (if uninteresting) FLWOR expression that is equivalent to
the even less interesting (but still valid) expression:
(23)
And a standalone "return" is illegal:
return (23) (: error :)
Where you have included parentheses below, you are calling a function
named "return" and XQuery works as expected. It's a bad idea to name a
function using a keyword as a name, but XQuery allows it. If you
replace "return(...)" with "foo(...)" in the expressions below, the
intended meaning will be clear.
The last two XQuery expressions should return errors (and do in the
online Zorba XQuery processor I tried them in). As noted above, this
is because there is no standalone use of the "return" keyword --
either the processor you are using has a bug or you haven't shown us
the entire expression.
Thanks,
-- Ron
On 10/1/2012 5:34 PM, Michael Sokolov wrote:
On 10/1/2012 10:48 AM, Michael Kay wrote:
There is no function called "return". Just remove the keyword.
Depending on the context, you might need to remove the outer curly
braces as well.
It's a little confusing because you can say
let $x:=0 return 23
but you can't say
return 23
Actually if you really start to dig, it becomes a lot confusing
you can say
let $x := 0 return (23)
but in that instance return is not a function call; the parentheses here
are constructing a sequence (of one item)
But if you say
declare default function namespace "x";
declare function return ($x) { $x+1 };
return (23)
that does seem to return 24 for at least one processor that I tried,
which seems truly bizarre (to me, anyway)
yet
declare default function namespace "x";
declare function return ($x) { $x+1 };
return 23
returns 23
while
declare default function namespace "x";
declare function return ($x) { $x+1 };
return return(23)
returns 24
-Mike Sokolov
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