Re: [xsl] Re: Keeping a running total?
2006-07-12 13:10:25
At 01:22 PM 7/12/2006, Ken wrote:
Consider that, with the given design, once you implement and debug a
given XSLT template rule, there is nothing possible *by design of
the language* that would break the functioning of that template
rule. I would think just that savings in debug time alone would
outweigh any savings in development time.
This is especially the case as documents and transformation
requirements scale up in complexity, as stylesheets become modular,
and as systems move towards layered mixes of off-the-shelf and custom
stylesheets, for example those handling XML formats such as Docbook,
TEI, ODF and what have you.
While I was never in the position of having to implement
transformations in pre-XSLT technologies (except DSSSL, which doesn't
count for these purposes), those who have (including Ken) can recall
for us the pain and suffering associated with scaling, maintenance
and reuse issues in the bad old days.
There is certainly a down side to XSLT's restrictions on variables,
but those generally tend to be felt by newcomers to the language
working on quick-and-dirty stylesheets, who (for whatever reasons bad
or good) are resisting learning new ways of thinking. (Steve I'm not
placing you in this camp; most beginners do not come straight out
with a problem stretching so far beyond XSLT's core competency.) Once
one has assimilated what David C has called "The XSL Way", it's
actually easier to think and design in it than it is to compose the
logic for procedural approaches. This is because the rules-based and
input-driven approach of XSLT tends to mirror specifications
themselves rather than the processes used to achieve their solutions,
which mostly end up being the business not of the stylesheet but of
the engine that executes it.
This is not to say that certain kinds of transformation are not be
easier or more straightforward using another technology or
programming paradigm. I think that will always be the case. (Yet I
hasten to note that no one has yet suggested XSLT pipelining as an
approach to the running-totals problem; not only would pipelining
and/or recursion make quick work of it, I bet, but also it is a
native technique in XSLT 2.0 -- which also does without mutable variables.)
As Ken also notes, there are also many ancillary advantages to
side-effect-free processing, which may be unimportant to particular
developers (like the broad availability of conformant tools in many
flavors) but which are very much to the benefit of developers in general.
Finally, we are now at a point where we can ask Darwin to judge. If
mutable variables are such an essential feature, would not XSLT, in
the years since 1999, have been superceded by a transformation
technology that included them? Maybe not, but such alternatives have
existed and still do exist.
Cheers,
Wendell
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- Re: [xsl] Re: Keeping a running total?, (continued)
- Re: [xsl] Re: Keeping a running total?, Andrew Franz
- Re: [xsl] Re: Keeping a running total?, Dimitre Novatchev
- Re: [xsl] Re: Keeping a running total?, Andrew Franz
- Re: [xsl] Re: Keeping a running total?, Steve
- Re: [xsl] Re: Keeping a running total?, Mukul Gandhi
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- Re: [xsl] Re: Keeping a running total?, G. Ken Holman
- Re: [xsl] Re: Keeping a running total?,
Wendell Piez <=
- RE: [xsl] Re: Keeping a running total?, Michael Kay
- Re: [xsl] Re: Keeping a running total?, Tracey Zellmann
- Re: [xsl] Re: Keeping a running total?, Colin Paul Adams
- Re: [xsl] Re: Keeping a running total?, Tracey Zellmann
- Re: [xsl] Re: Keeping a running total?, Colin Adams
- Re: [xsl] Re: Keeping a running total?, Steve
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- Re: [xsl] Re: Keeping a running total?, Wendell Piez
- Re: [xsl] Re: Keeping a running total?, David Carlisle
- Re: [xsl] Re: Keeping a running total?, Wendell Piez
- Re: [xsl] Re: Keeping a running total?, Dimitre Novatchev
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