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Changing the XProcStep interface?

From: Norman Walsh <ndw@nwalsh.com>
Date: Sun, 19 Apr 2015 18:46:04 -0700
To: XProc Dev <xproc-dev@w3.org>
Message-ID: <87h9sbtvvn.fsf@nwalsh.com>
Hello world,

The XProcStep interface, com.xmlcalabash.core.XProcStep is:

public interface XProcStep extends XProcRunnable {
    public void setInput(String port, ReadablePipe pipe);
    public void setOutput(String port, WritablePipe pipe);
    public void setParameter(QName name, RuntimeValue value);
    public void setParameter(String port, QName name, RuntimeValue value);
    public void setOption(QName name, RuntimeValue value);
}

XProcRunnable is just reset() and run().

I'm thinking of adding a static configureStep method:

    public static void configureStep(XProcRuntime runtime);

This would be called during configuration, before any pipelines have
been parsed. I'm currently using it (through reflection, without
changing the interface) to tinker with the URIResolver so that I can
resolve step declarations without hitting the network.

For example, in the next release of the cx:asciidoctor step, you'll
be able to use

  <p:import href="http://xmlcalabash.com/extension/steps/asciidoctor.xpl"/>

And that will get the declaration for the cx:asciidoctor step, but it
will never have to go to the network to get it.

On the one hand, changing interfaces in Java is a real problem.
Anything that uses that interface will have to be *recompiled*.
There's a reason that the Java platform never allows java.* and
javax.* packages to change an interface after it's published!

And reflection works.

On the other hand, reflection is a subversive and undocumented way to
change an interface! I'd rather change it, but I don't have to, at
least not in XMLCalabash1. I'm sure I'll do something different in
XMLCalabash2.

I think I've just about convinced myself not to change it, but since
I've typed all this up, I guess I'll send it :-)

Thoughts?

                                        Be seeing you,
                                          norm

-- 
Norman Walsh
Lead Engineer
MarkLogic Corporation
Phone: +1 512 761 6676
www.marklogic.com

Received on Monday, 20 April 2015 01:46:30 UTC

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