Re: [xsl] variable incrementing in XSLT -- XSLT spec

Subject: Re: [xsl] variable incrementing in XSLT -- XSLT spec
From: "Udi" <udi@xxxxxxxxxxxxx>
Date: Fri, 27 Jun 2003 12:01:32 -0500
of course the choice of word 'variable' is unfortunate cuz it may indicate
to the uninitiated 'something that could possibly vary' .
something like 'term' or 'item' would've been a bit less confusing.

----- Original Message ----- 
From: "David Carlisle" <davidc@xxxxxxxxx>
To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Friday, June 27, 2003 11:35 AM
Subject: Re: [xsl] variable incrementing in XSLT -- XSLT spec


>
> > Myself and many of us
> > fell that it a major handicap in writing programs
> > easily in XSLT.
>
> Side effect free programming is not unique to XSLT, it is a long
> established programming paradigm, designed to make things easier and
> more natural for people. It allows many optimisation strategies that are
> not available in imperative programming languages as code may be
> re-written and re-arranged by the optimiser with much more freedom.
>
> the use of "variable" in functional languages such as XSLT matches the
> use of the word in mathematics (where it originates). there is nothing
> at all natural in variables that change their value, that was an
> introduction in imperative programming languages which (due to
> limitations at the time) are designed to more closely model the machine
> implementation than the natural specification of a problem.
>
> > If there is a feature of full scale variables in XSLT, it
> > would make programming really easy.
>
> Not at all. If for example you could set a variable in one template and
> use its value in another, it would constrain the processor to evaluate
> templates in a specific order, which is not the case now, evaluation
> might be in any order, or parallelised across different threads, the
> fact that each template only returns a single result (like a
> mathematical function0 not change the state of arbitrary number of otehr
> variables makes this much easier to understand.
>
> David
>
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