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[xsl] The real harm is in functions with side effects (Was: Re: Using Extension Functions - Its Efficiency)

Subject: [xsl] The real harm is in functions with side effects (Was: Re: Using Extension Functions - Its Efficiency)
From: "Dimitre Novatchev" <dnovatchev@xxxxxxxxx>
Date: Fri, 16 Jan 2004 06:52:14 +0100

"Joshua Allen" <joshuaa@xxxxxxxxxxxxx> wrote in message
> Well, doing so partially defeats the purpose of using XSLT, since it
> means your stylesheets will not work in many other systems.  It begs the
> question, if you find that Java is needed, then why use XSL at all?  Why
> not just write the app in Java?
> In any case, if you want to still use XSL and be as portable as
> possible, I would recommend using the exslt templates at www.exslt.org
> before giving up and writing your own extensions.

Portability is not the main issue with using extension functions.

In many cases an application is designed to work only within a certain known
platform/environment (e.g. intranet), which is not going to change.

However, even in this case uncontrolled use of extension functions can be
dangerous. What I am referring to is that many people are not aware of the
harm that functions with side effects may cause in a functional language.

In many cases the "need" to use an extension function is due only to the
fact that the programmer comes from a procedural background and simply does
not want to learn the functional way of programming -- and not because there
is no way to do this without extension functions.

Due to this reason some nice-looking proposals for new extension functions
(which happen to have side effects) have not been accepted by the management
of the EXSLT.org group.

We need to have a special section in the XSLT FAQ about extension functions
and why functions with side effects are generally harmful in a functional

Dimitre Novatchev.
FXSL developer,

http://fxsl.sourceforge.net/ -- the home of FXSL
Resume: http://fxsl.sf.net/DNovatchev/Resume/Res.html

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