Converter Java API

I am currently playing around with Java converters.

One thing that came up is that asciidoctor Ruby directly calls the registered converter.
Therefore it passes a JRuby object that implements AbstractBlock (or AbstractNode) to the convert method and not an implementation provided by asciidoctorJ, e.g. a BlockImpl.

public interface Converter {
    Object convert(AbstractBlock node);
    Object convert(AbstractBlock node, String transform); // Always gets a org.jruby.gen.InterfaceImpl on initial invocation
}

I'd like to propose adding new methods to AbstractConverter that always get the correct Java counterpart of the node and AbstractConverter.convert() is implemented to transform the JRuby node and invoke this new method:

package org.asciidoctor.converter;

public abstract class AbstractConverter implements Converter {

    public Object convert(AbstractNode node) {
        AbstractNode javaNode = ...;// share impl from AbstractBlockImpl.overrideRubyObjectToJavaObject()
        return convertNode(javaBlock);
    }
    public Object convert(AbstractNode node, String transform) {
        AbstractNode javaNode = ...;// share impl from AbstractBlockImpl.overrideRubyObjectToJavaObject()
        return convertNode(javaBlock, transform);
    }

    public abstract Object convertNode(AbstractNode node);

    public abstract Object convertNode(AbstractNode node, transform);
}

An alternative would be decorate the converter.
But that would require to generate these converters unless we only support instance based converters. (That is Converter instances are registered instead of their classes.)

What do you think?

Kind regards,
Robert

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Just tried your proposal:

I have two simple convert methods in the Converter interface that should be called by asciidoctor Ruby:

public interface Converter {
    Object convert(IRubyObject node);
    Object convert(IRubyObject node, String transform);
}

And the AbstractConverter adds these methods so that a Java developer can stick with the well-known convert() methods:

public abstract class AbstractConverter implements Converter {

    @Override
    public final Object convert(IRubyObject node) {
        AbstractBlock javaBlock = overrideRubyObjectToJavaObject(node);
        return convert(javaBlock);
    }

    @Override
    public final Object convert(IRubyObject node, String transform) {
        AbstractBlock javaBlock = overrideRubyObjectToJavaObject(node);
        return convert(javaBlock, transform);
    }

    protected abstract Object convert(AbstractBlock node);

    protected abstract Object convert(AbstractBlock node, String transform);
...
}

It works... but unfortunately I get this warning in the console which makes me think that it is rather luck that the correct methods were called:

C:/work/git/asciidoctorj/asciidoctorj-core/build/resources/main/gems/asciidoctor-1.5.2/lib/asciidoctor/abstract_block.rb:71 warning: ambiguous Java methods found, using convert(org.jruby.runtime.builtin.IRubyObject)

I also tried playing with adding

@JRubyMethod(name="__convert_java__")

 on the java counterparts, but  it does not have any effect. (I must admit that I did not really understand that, sth I have to read about over the holidays. :) )

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NAML