Thank you, Michael!
On Thu, Apr 23, 2020 at 1:00 PM Michael Kay mike(_at_)saxonica(_dot_)com <
xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
1. I think the advantage of using <xsl:package> over <xsl:import> and
<xsl:include> for my case (importing a single function [but see below about
arity]], from a package that does not import anything itself) is that I can
expose only the function that I want to expose, and not any other named
components of the imported package (variables, helper functions, etc.). If
that understanding is correct, it does sound like an advantage. (I want to
be able to run the code in Saxon HE, so being able to precompile the
package, which would be a benefit under other circumstances, would not be
relevant in this case.)
Certainly, being able to restrict what you expose is one of the benefits
of using packages. Also, you have much more control over what can be
overridden, and how; it's the fact that overrides must be type-compatible
that enables packages to be separately compiled.
2. I don't understand how (or whether it is possible) to import packages
without setting up a configuration file. If it isn't, that would seem to be
a disadvantage for my use case, since anyone else who wanted to use my
function library would have to set up a configuration, as well., and not
just get a copy of the package file itself If I have understood correctly,
the spec seems to say that the configuration is implementation-dependent,
so if one is needed, where would I find documentation about how to set it
up for use by Saxon, both at the command line and inside <oXygen/>? If a
configuration setup is not required—that is, if it is possible to specify
the file-system location of the imported package directly inside the
importing one— how do I specify the location of the imported package in
<xsl:use-package>, given that I would want the path to be relative to the
importing stylesheet? Is the procedure for doing that the same as with
<xsl:include> and <xsl:import>?
Configuration files are an artefact of the Saxon implementation, nothing
to do with the spec, which leaves the mechanism for locating a package
implementation-dependent. You can't specify a relative path location for a
used package (though, as I'm beginning to understand the JS common module
system better, I think I can see how we could add that option). But there
are alternatives to using a configuration file; you can use
XsltCompiler.importPackage() in the s9api API, or the -lib option on the
Transform command line.
3. On a semi-related topic, I want my function to have one-argument and
two-argument versions. Since function parameters cannot be optional, I
think a fairly straightforward way to do this would ge to put the code in
the two-argument version, and have the one-argument version supply a
default for the missing argument and then use it to pass the call along to
the two-argument version. Is this the best way to deal with optional
function arguments?
Yes. (In my paper at XML Prague -- see
http://www.saxonica.com/papers/xmlprague-2020mhk.pdf §3.3) I proposed
adding syntactic sugar to make this easier.)
Michael Kay
Saxonica
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