Re: [xsl] Re: Assignment no, dynamic scoping si (was: Wishes for XSL revisions ...

[Gunther Schadow <gunther at aurora dot regenstrief dot org>]

Mike Haarman wrote:


>>There is no question about side-effects and global variables in
>>the imperative programming style. I didn't ask for any of this
>>to be added to XSLT. What I was asking for was dynamic scoping,
>>at least an option to be able to use dynamic scoping for some
>>variables. I also said that without dynamic scoping I could see
>>little reason for calling variables variables, because they are
>>fixed value bindings that I could just simply lexically substitute
>>wherever they are used (except where an RTF is constructed.)
>>
>>
> 
> It should be possible to give a semblance of dynamic scoping by wrapping
> your processor in a class which maintains access to and value of symbols
> which the stylesheet references via an extension.  I should think.  I've
> never done anything like this in practice.  What are the limitations to
> such an approach?


There is even a simpler approach using only XSLT: I can make all
templates use an argument that is a constructed node-set
containing name-value pairs (the dynamic environment) and references
to the bindings in this environment would be supported by some
xpath selects in that environment node-set.

However, the problem with any of these things is that they are
either external additions or internal style rules none of which
work well in a larger distributed environment. I can write my
own systems to work that way, my own XSLT sheets to conform
with my styles but as soon as I collaborate with others, we get
into interoperability problems. That's why it is important to
have a few basic constructs in the language standard.

regards
-Gunther


-- 
Gunther Schadow, M.D., Ph.D.                    gschadow@regenstrief.org
Medical Information Scientist      Regenstrief Institute for Health Care
Adjunct Assistant Professor        Indiana University School of Medicine
tel:1(317)630-7960                         http://aurora.regenstrief.org



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