RE: Cannot compile stylesheet that passes Java object as template par ameter

[Santiago Pericas-Geertsen <Sa...@Sun.COM>]

Ralph,

 Yes, that is a known issue. The problem is that XSLTC implements most
of its type checking statically, and there are some problems with
xsl:param and non-XSLT types. In particular, the type of a parameter
cannot be determine statically in XSLT, which means that if you pass a
GregorianCalendar as a parameter to a template, its type will be
subsumed to Object. Consequently, you won't be able to call any useful
methods on that param unless you downcast it (which is possible using an
XSLTC extension, but it is of course not portable). 

 In summary, even if the type checker is changed to allow arbitrary
conversions to Reference (i.e. the type a parameter) this may still not
be the end of the story. However, if you find it useful, it is a very
simple change. See attachment for an example of how to use xsltc:cast().

-- Santiago

On Thu, 2004-06-24 at 16:49, Ralph Brenner wrote:

> Hi Santiago,
> 
>  
> 
> Thanks for the fix!  It does indeed address the problem for Java
> *String* objects.  
> 
> However, there still exists a problem for other types of Java
> objects.  For example, 
> 
> the following XSLT processes fine with org.apache.xalan.xslt.Process
> but generates
> 
> an error when I try to compile it with
> org.apache.xalan.xsltc.cmdline.Compile:
> 
>  
> 
>      Cannot convert data-type 'java.util.GregorianCalendar' to
> 'reference'.
> 
>  
> 
> The goal is to be able to pass any Java object to a template and then
> be able to 
> 
> execute methods against it.
> 
>  
> 
>  
> 
> EXAMPLE XSLT:
> 
> -------------
> 
>  
> 
> <?xml version="1.0" encoding="UTF-8"?>
> 
> <xsl:stylesheet
> 
>     xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
> 
>     xmlns:java="http://xml.apache.org/xalan/java"
> 
>     version="1.0">
> 
>  
> 
>     <xsl:template match="/">
> 
>         <xsl:variable
> 
>             name="javaObject"
> 
>             select="java:java.util.GregorianCalendar.new()"/>
> 
>         <xsl:call-template name="aTemplate">
> 
>             <xsl:with-param name="javaObject" select="$javaObject"/>
> 
>         </xsl:call-template>
> 
>     </xsl:template>
> 
>  
> 
>     <xsl:template name="aTemplate">
> 
>         <xsl:param name="javaObject"/>
> 
>         <xsl:value-of select="java:getTime($javaObject)"/>
> 
>     </xsl:template>
> 
> </xsl:stylesheet>
> 
>  
> 
>  
> 
> Regards,
> 
>    Ralph
> 
>  
> 
>  
> 
> -----Original Message-----
> From: Santiago Pericas-Geertsen
> [mailto:Santiago.Pericasgeertsen@Sun.COM] 
> Sent: Thursday, June 24, 2004 9:16 AM
> To: Ralph Brenner
> Cc: 'xalan-j-users@xml.apache.org'
> Subject: Re: Cannot compile stylesheet that passes Java object as
> template par ameter
> 
>  
> 
> Ralph,
> 
> Please try the current CVS. A related bug has been fixed today. Hope
> it works for you.
> 
> -- Santiago
> 
> On Wed, 2004-06-23 at 19:22, Ralph Brenner wrote: 
> 
> I am unable to compile a stylesheet that passes a Java object as a
> parameter to a template.  For example, when trying to pass a Java
> String, I get the following error:
> 
>     Cannot convert data-type 'java.lang.String' to 'reference'.
> 
> However, I am able to successfully process the template when I do not
> compile it.
> 
> e.g. this does not work:
>    java org.apache.xalan.xsltc.cmdline.Compile example.xsl
> 
> But this works:
>    java org.apache.xalan.xslt.Process -XSL example.xsl
> 
> Here is an example XSL file which illustrates the problem:
> 
> example.xsl:
> 
> <?xml version="1.0" encoding="UTF-8"?>
> <xsl:stylesheet
>     xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
>     xmlns:java="http://xml.apache.org/xalan/java"
>     version="1.0">
>     
>     <xsl:template match="/">
>         <xsl:variable
>             name="javaString"
>             select="java:java.lang.String.new('java variable test')"/>
>         <xsl:call-template name="aTemplate">
>             <xsl:with-param name="javaString" select="$javaString"/>
>         </xsl:call-template>
>     </xsl:template>
> 
>     <xsl:template name="aTemplate">
>         <xsl:param name="javaString"/>
>         <xsl:value-of select="$javaString"/>
>     </xsl:template>
> </xsl:stylesheet>
> 
> 
> 
>