Re: Tip?

Hence my proposal to take an initiative towards EXPath standardization, now that we have maps. 

I understand the problem: EXPath is about XPath functions, and an XPath function cannot be required to support XQuery evaluation. But nevertheless I suggest to standardize an evaluation function supporting the use of variable declarations (and thus giving a target for explicit bindings), even if it's not XPath and the expression is constrained to be pure XPath (important when thinking of XSLT). The spec might make clear that the argument string consists of two parts - an optional prefix part consisting of one or more variable declarations using XQuery syntax - followed by the expression itself, which implementers might either constrain to be an XPath expression, or allow to be an XQuery expression.
 

    Michael Kay <mike@saxonica.com> schrieb am 9:28 Freitag, 26.August 2016:
 

 

Michael, I wonder if your worries about preventing optimization are not taken care of by the approach BaseX takes. To recapitulate: the BaseX approach is to supply *explicit* bindings to external variables declared within the expression; the bindings are passed in via a map argument providing the name/value pairs. Example:
let $x := 1 return
xquery:eval('declare variable $y external; $y + 1', map{'y': $x})


Ah, right, I missed that. That is of course essentially what saxon:evaluate does except that it predates maps, so you can only bind to one of the fixed names $p1 to $p9. Plus we're dealing with XPath rather than XQuery so there's no declaration:
saxon:evaluate("$p1 + 1", $x)
Michael KaySaxonica