Re: [xsl] the "use" parameter for a key is to be a path expression

Subject: Re: [xsl] the "use" parameter for a key is to be a path expression
From: "Thomas B. Passin" <tpassin@xxxxxxxxxxxx>
Date: Wed, 27 Feb 2002 14:05:52 -0500
[Jeni Tennison]

>
> > You were right about the leading and trailing spaces, but I'm
> > intruiged that you say that the use parameter for a key has to be an
> > XPath expression: in that case what about all the examples I have
> > seen using concat(@this,'+',@that)?
>
> The XPath:
>
>   concat(@this, '+', @that)
>
> *is* an expression. Possibly you (or Tom P?)

    Yes, it was me (Tom P), Jeni.

>are confusing the general
> term "expression" with the more specific term "path expression" - a
> path expression is just one kind of expression, function calls are
> another, literal strings are another and so on.

I was going by what I saw in Mike's book, where it says tha the value is an
"Expression, and "The expression used to determine the value of the key for
each of these modes").  Also, still in the book, when I lookup "expression",
I find "The syntax of expressions is defined in the XPATH Recommendation,
and is described in detail in chapter 5.'  Chapter 5 is in fact about xpath
expressions.  This all makes it look like we're dealing with xpath
expressions in the use attribute.  But it's not the Rec, is it?

I've been bitten before by thinking that an "expression" can include a
string expression where it actually can't, and now I usually assume that any
problems with "expressions' not seeming to work come from string expressions
not being allowed.  Of course, when you are working on your own code and can
see the actual error messages you may get more guidance.


> The use attribute
> takes an expression, which can be any of those sorts of expression.
>

Good, thanks for clearing that up.

Cheers,

Tom P


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