Re: [xsl] user-defined XSLT functions and stylesheet variables?

["Eliot Kimber ekimber@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

I think the use case here is not really a support for global variables but for
appropriately-managed global configuration. I think thatbs a special case
separate from a more general (ill-advised) use of global variables.



That suggests that Mike Kaybs assertion that a global variable is just an
implicit zero-arity function is an important insight.



If a global variable is simply providing access to a static (at runtime) but
changeable (over time) configuration then it could just as easily be provided
by a function that reads the values from an external file or any other
external data source. That external configuration file could be a separate
XSLT module that holds the data if thatbs the most convenient way to
implement it.



But it also suggests that you are probably better served by defining the
function if you need to ensure re-usability and portability of the code, for
all the reasons webve given.



So I think I can continue to assert my absolutist opinion: all global
variables should be rewritten as functions or as parameters passed as needed.



Cheers,



E.



--

Eliot Kimber

http://contrext.com







From: "Graydon graydon@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
Reply-To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Date: Saturday, June 19, 2021 at 7:35 PM
To: <xsl-list@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [xsl] user-defined XSLT functions and stylesheet variables?



On Sun, Jun 20, 2021 at 12:11:50AM -0000, Christophe Marchand
cmarchand@xxxxxxxxxx scripsit:

All the responses given by Eliot and Liam respect Clean Code[1] best

practises. Many principles must be respected if you expect your code may

evolve :



I think this is one of those places where the imperative best practise

and the declarative best practise aren't perfectly congruent.



If you've got a global variable that provides part of the transform

context -- the big map of what the known languages use for quotation

marks, commas, and colons, say -- I think it's quite entirely harmless

to reference that from inside a function.  The testing should be looking

at the list of names in the map and making sure the expected names are

defined for each language, but presence of a transform context with

global constants -- how many of whatever to the EMU, how many points to

the inch, etc. -- is conceptually like amending the static context by

importing module functions.  I don't think it's harmful to use global

variables in this way.



(It does make me hope XSLT 4 allows



<xsl:variable name="bigLookup" as="map(*)">

  <xsl:map>

  ....

  </xsl:map>

</xsl:variable>



to be declared static.)



--

Graydon Saunders  | graydonish@xxxxxxxxx

CC&s oferC)ode, C0isses swC! mC&g.

-- Deor  ("That passed, so may this.")