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Mukul,
I'm also curious as to why this restriction is imposed on XSLT, and never fail to listen with interest to cogent explanations of the theory behind functional, "side-effect-free" programming.
However, otherwise I disagree. I like XSLT's functional aspects, and am greatly relieved not to have to pay attention to the kinds of things that more procedural languages burden the programmer with. In other words, I do not believe that this design decision represents a net loss, or that XSLT would be "really easy" if it allowed more side effects: on the contrary, I'm thankful that I can only imagine what XSLT would be like if it were more procedural.
After all, if you like that kind of programming there are plenty of tools available. People used to write markup transforms in Perl, and it's still very useful if you know what you're doing.
I think experience on this list also shows that many times, neither an incrementable variable nor recursion is really necessary. (And note that on the list we see the hard cases, and never hear about all the things that are easy.) Just as often, when the "problem" of variable scoping comes up, a programmer who is not familiar with the XSLT processing model is jumping to conclusions about how something needs to be done. XSLT lets the programmer concentrate on the "what", leaving most details of "how" to the engine. For whatever reason, some programmers don't understand this or don't like it, and insist on thinking too hard. (Admittedly there's a blurry line there. But note also that recursion and such sophisticated techniques come up on the list more often to handle problems that XSLT wasn't designed to deal with, like string munging, than they do just to get around the restrictions on variables.)
Just $0.02 from me. Interesting question.
At 12:10 PM 6/27/2003, Mukul wrote:
XSL-List info and archive: http://www.mulberrytech.com/xsl/xsl-list
Re: [xsl] variable incrementing in XSLT -- XSLT spec
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Subject: Re: [xsl] variable incrementing in XSLT -- XSLT spec From: Wendell Piez <wapiez@xxxxxxxxxxxxxxxx> Date: Fri, 27 Jun 2003 13:50:29 -0400 |
Mukul,
I'm also curious as to why this restriction is imposed on XSLT, and never fail to listen with interest to cogent explanations of the theory behind functional, "side-effect-free" programming.
However, otherwise I disagree. I like XSLT's functional aspects, and am greatly relieved not to have to pay attention to the kinds of things that more procedural languages burden the programmer with. In other words, I do not believe that this design decision represents a net loss, or that XSLT would be "really easy" if it allowed more side effects: on the contrary, I'm thankful that I can only imagine what XSLT would be like if it were more procedural.
After all, if you like that kind of programming there are plenty of tools available. People used to write markup transforms in Perl, and it's still very useful if you know what you're doing.
I think experience on this list also shows that many times, neither an incrementable variable nor recursion is really necessary. (And note that on the list we see the hard cases, and never hear about all the things that are easy.) Just as often, when the "problem" of variable scoping comes up, a programmer who is not familiar with the XSLT processing model is jumping to conclusions about how something needs to be done. XSLT lets the programmer concentrate on the "what", leaving most details of "how" to the engine. For whatever reason, some programmers don't understand this or don't like it, and insist on thinking too hard. (Admittedly there's a blurry line there. But note also that recursion and such sophisticated techniques come up on the list more often to handle problems that XSLT wasn't designed to deal with, like string munging, than they do just to get around the restrictions on variables.)
Just $0.02 from me. Interesting question.
Cheers, Wendell
At 12:10 PM 6/27/2003, Mukul wrote:
We all know that XSLT does not allow incrementing a variable after declaring it. Myself and many of us fell that it a major handicap in writing programs easily in XSLT. To simulate the variables we have to use recursion and many sophisticated techniques. If there is a feature of full scale variables in XSLT, it would make programming really easy. I am curious why this restriction is imposed in XSLT specification.
====================================================================== Wendell Piez mailto:wapiez@xxxxxxxxxxxxxxxx Mulberry Technologies, Inc. http://www.mulberrytech.com 17 West Jefferson Street Direct Phone: 301/315-9635 Suite 207 Phone: 301/315-9631 Rockville, MD 20850 Fax: 301/315-8285 ---------------------------------------------------------------------- Mulberry Technologies: A Consultancy Specializing in SGML and XML ======================================================================
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