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Re: [xsl] [XSLT 3.0] Question about the simplified syntax of a package

2014-11-11 09:03:12
 Thank you, Abel,

This all makes sense except the confusing point that anything at all
should be exposed in a "package" that is not intended to be used by
other packages.

Unless we consider a command-line invocation as "using-package".

Cheers,
Dimitre

On Tue, Nov 11, 2014 at 3:28 AM, Abel Braaksma (Exselt)
abel(_at_)exselt(_dot_)net 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

1. As we see from the code above, only modes and named templates will be
exposed in the equivalent xsl:package.

Is it correct to conclude that if the principal stylesheet module contains 
any
components of type: function, attribute-set, accumulator, keys and global
variables / parameters, these are not exposed and cannot be accessed from
a using package? If so, what was the reason for this decision?

Keys are never exposed, they are always local, non-static parameters are 
always global, static params are always local (visible only to the containing 
package).

I am not sure why the rest (functions, accumulators, global variables) are 
not getting a default visibility of "public". The reasoning for xsl:mode and 
xsl:template being public is that in XSLT 2.0, these components were visible 
to the caller of the stylesheet (i.e., from commandline or programming 
interface). However, since in XSLT 3.0 you can have an initial function, I'd 
say that functions should be public as well. Officially, accumulators and 
variables cannot be set by the caller, so it does not seem to make sense to 
make them public as well.

Reading through this bug https://www.w3.org/Bugs/Public/show_bug.cgi?id=24307 
shows the reflection of a discussion where templates, functions and modes are 
mentioned as implicitly public. From that, it seems indeed an omission 
(unless another bug covered the function situation, but I could not find it).

Another thought that comes to mind is that with the resolution of bug 
https://www.w3.org/Bugs/Public/show_bug.cgi?id=26468, there is no real need 
to make XSLT 3.0 components (including initial functions) implicitly public, 
all you need to do is change your XSLT 3.0 stylesheet root element into 
xsl:package and add a name attribute.

I raised a new bug here to reflect your concerns: 
https://www.w3.org/Bugs/Public/show_bug.cgi?id=27300.


2. Because the produced by the transformation above equivalent package
doesn't have any "name" or "package-version" attributes specified, how
should an <xsl:use-package> in a using package reference the package
generated by the transformation?

You cannot reference a simplified package, this transformation is in place 
for backwards compatibility, turning existing XSLT 2.0 stylesheets into 
packages (as in "everything is a package" in XSLT 3.0), so the @name and 
@package-version do not make sense. Simplified packages can only be used as 
principal (or "top level", as opposed to "library") package. It fits with the 
following two rules in section 3.6 Packages:

"A package typically has a name, given in its name attribute, which must be 
an absolute URI. Unnamed packages are allowed, but they can only be used as 
the "top level" of an application; they cannot be the target of an 
xsl:use-package declaration in another package."

and:
"A package may have a version identifier, given in its package-version 
attribute. This is used to distinguish different versions of a package. The 
value of the version attribute, after trimming leading and trailing 
whitespace, must conform to the syntax given in 3.6.1 Versions of a Package. 
If no version number is specified for a package, version 1 is assumed."

Cheers,

Abel Braaksma
Exselt XSLT 3.0 streaming processor
http://exselt.net


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