RE: [xsl] how can I modify global variables ?

["Ben Robb" <b dot robb at cscape dot com>]

Moreover, a variable defined in one template is not accessible in other
template, since it is in local template scope. A *globally* scoped
variable is defined as a child of the <xsl:stylesheet> node. This also
cannot be changed once set. Understanding why this is so is almost
always the first major conceptial problem people have to get through to
understand XSLT.

The reason why you cannot change a variable once it has been set is
because of the fact that it is a functional programming language [and
I'm not going to even try and explain what that means with people like
David Carlisle on the list *grin*]. Basically, XSLT is a so-called
"side-effect free" language - that is, the processor does not have to
deal with the fact calling a template might change a variable, and so
does not have to keep track of the variable value in memory. This leads
to generally faster processors of a language.

All that said, when you come down to it, the practical implication of
this is that you cannot change a variable or parameter once set.... and
I've yet to find a situation where this is an insurmountable problem -
you just need to think about the problem in a slightly different way.

Ben

> -----Original Message-----
> From: FINLEY, Mike [mailto:Mike.FINLEY@sema.co.uk]
> Sent: 12 April 2001 12:20
> To: 'xsl-list@lists.mulberrytech.com'
> Subject: RE: [xsl] how can I modify global variables ?
> 
> 
> The short answer is "you can't". Once a variable is created, its value
> cannot be changed.
> 
> -----Original Message-----
> From: Gabriel Erzse [mailto:erzse.gabriel@romobtec.ro]
> Sent: 12 April 2001 11:57
> To: xsl-list@lists.mulberrytech.com
> Subject: [xsl] how can I modify global variables ?
> 
> 
>     If I have template called "root" (for example) where I defined a
> variable called "rowCount" and from "root" template I call 
> another template
> called "compute", is it possible to change the value of the "rowCount"
> variable from inside "compute" template ?
> 
>    If yes, how can I do it ?
> 
>    Thanks,
>    Gabriel Erzse.
> 
> 
>  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
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