[xsl] Re: What is the best way to cast integer to string in XSLT2?

Subject: [xsl] Re: What is the best way to cast integer to string in XSLT2?
From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx>
Date: Sun, 11 May 2003 16:59:26 +0200
Thanks a lot Jeni and Andrew,

> This is a good example of what I meant during my talk at XML Europe
> about life getting harder for XSLT users because of the strong typing
> in XPath 2.0. XPath 2.0 allows implicit casting:
>  1. from xdt:untypedAtomic (the type of untyped nodes) to any atomic
>     type
>  2. from any atomic type to its base type (up the atomic type
>     hierarchy)
>  3. from xs:decimal (and its subtypes) to xs:float or xs:double and
>     from xs:float to xs:double
> As you say, it is possible to cast values of most types into a string
> (exceptions are xs:QName and xs:NOTATION), but in terms of the type
> hierarchy used by XPath 2.0, it is not the case that every type is
> derived from xs:string. (I guess you're aware of the recent XML-Dev
> discussion on this topic.) So you have to perform the casting
> explicitly.

Do any examples exist when such implicit casting would be
dangerous/counter-intuitive? If not, then it would be very useful to allow
implicit casting to string. In C++ one can specify a constructor that takes
a single argument og another type, e.g.:

class complex
     double re, im;

     complex (double r) : re(r), im(0) {}


Then the programmer simply writes:

    complex a = 7;

instead of

    complex a = complex(7);

In cases like the current one I think such "conversion constructors" should
be specified in the XPath data model. This makes writing and understanding a
program much more easier.

> > 2. My current solution is to use
> >
> >   string(position())
> >
> > Is this the best/recommended solution?
> Yes. For atomic values like the integer returned by position(), it
> returns the same as xs:string(position()); the latter is just longer
> and requires an extra namespace declaration.



Dimitre Novatchev.
http://fxsl.sourceforge.net/ -- the home of FXSL

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