[Xpath-ng] xpath-ng requirements

[David Rosenborg]

Hi Bryan,

> So an expression should default to for any if no explicit operator is
> found? I'm willing to vote yea on that.

Not sure, I'm just saying that explicit syntax for for-all and for-any
would improve the language.

> When we talk about function libraries I wonder if there shouldn't be
> some way of using a range of exslt functions as basic functions. 

If I understand you right, that's what I try to achive with the
import declaration as I proposed in a recent post:

namespace math = "http://xpathng.org/ns/math"
import math:*

Some have objected to have this ability in the XPath NG core language.
In the case where you don't have it in the core language, the host language
could still provide the same functionality e.g. XSLT-NG you could have top
level elements expressing the same thing.

> >Yes, I think we should allow arbitrary expressions as path steps.
> 
> Okay so when you say arbitrary expressions you don't just mean the union
> examples from this req. but also stuff like(from W3C examples)
> document("otherdoc.xml")/key("x","foo")/a/b

Yes, anything, including function calls.

> I voiced complaints against conditional expressions more completely when
> the group first began, first I dislike them because I suppose that if I
> were working in a language with which I am not extremely comfortable I
> would probably be tempted to put such logic as exemplified by conditions
> into the language with which I am comfortable thereby causing those who
> come after, such as might be expected to have their language preferences
> reversed, to have debugging problems.
> The other debugging problem is that it has been my observation
> that many problems in comprehension for people with xslt has not so much
> had with xslt to do, as it has with extremely knotty xpaths to do, I do
> not suppose that conditionality will make the xpaths more knotty but
> rather that people will have two places to look at to try and determine
> "why is my template not selecting anything?" There is an already
> intrinsic conditionality in parts of xpath 1.0, not() for example, and I
> notice that people often have a hard time getting their heads around
> if="not(someLongexpressionHere)".

Well, I believe that conditional expressions are about the least complex
thing we are discussing for inclusion in XPath NG.

Cheers,
David