Saxon

My above #1 idea is not working, as clearPerTransformationData() is called at the beginning of Controller.transform(Source source, Receiver receiver) - clearing about any userData I had set in advance.

Are there any other suggestions I should consider, shy of resorting to something based on a ThreadLocal here?

Michael - thanks. I found the Controller.getParameter(), but it is not able to access the parameters I had set due to what I had mentioned above:

...TransformerImpl.setParameter - which among other things, will immediately return without setting anything if the parameter was not found to exist on the xsltExecutable / defined as a parameter within the XSLT. ...

Maybe deserving for a new ticket under "JAXP Java API", from https://docs.oracle.com/javase/7/docs/api/javax/xml/transform/Transformer.html#getParameter%28java.lang.String%29 :

public abstract Object getParameter(String name)

Get a parameter that was explicitly set with setParameter.

However, as of Saxon 9.6, this is no longer the case. Consider the following test code:

	public void test() throws Exception{
		// Java 1.8.0_25 default:
		test(transformerFromXslt(TransformerFactory.newInstance(
			"com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl", getClass().getClassLoader())));
		
		// Apache Xalan-2.7.1:
		test(transformerFromXslt(TransformerFactory.newInstance(
			"org.apache.xalan.processor.TransformerFactoryImpl", getClass().getClassLoader())));
		
		// Saxon-HE-9.6.0-2:
		test(transformerFromXslt(new net.sf.saxon.TransformerFactoryImpl()));
	}
	
	protected Transformer transformerFromXslt(final TransformerFactory tf) throws Exception{
		final StreamSource ss = new StreamSource(getClass().getResourceAsStream("Identity.xslt"));
		final Templates templates = tf.newTemplates(ss);
		final Transformer transformer = templates.newTransformer();
		return transformer;
	}
	
	protected void test(final Transformer t){
		System.out.println("t.getClass: " + t.getClass());
		
		t.setParameter("testParam", "good");
		System.out.println("t.getParameter: " + t.getParameter("testParam"));
	}

The following output is generated:

t.getClass: class com.sun.org.apache.xalan.internal.xsltc.trax.TransformerImpl
t.getParameter: good
t.getClass: class org.apache.xalan.transformer.TransformerImpl
t.getParameter: good
t.getClass: class net.sf.saxon.jaxp.TransformerImpl
t.getParameter: null

It appears that Saxon is no longer compliant here with the JAXP API.

Agreed on all of your points - and thank you for fixing the easy fix!

Would you please further consider ensuring that all set parameters can be accessed from the XPathContext object - either through the Controller, or possibly providing an accessor to the current Transformer, e.g. XPathContext.getTransformer() (with the understanding it would be null for non-XSLT contexts, similar to @XPathContext.getController()@)?

Alternatively, any parameters that are set "today" (in 9.6.0-2) are available through the alternate syntax of Controller.getParameter() - as you mentioned above. The only problem was that parameters that were set that weren't defined were not being persisted into the bindery. If it would be possible to allow such parameters to pass-through as a "Java" type, I think this would provide for both concerns - allowing such parameters to be returned by both Transformer.getParameter() as well as @Controller.getParameter()@.

I will be more than willing to file an additional enhancement request for one or both of these suggestions, if you would be in agreement.

Thanks again!