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 * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
 * Institute of Molecular Cell Biology and Genetics.
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 *    this list of conditions and the following disclaimer.
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package org.scijava.module.process;

import org.scijava.Priority;
import org.scijava.module.Module;
import org.scijava.module.ModuleItem;
import org.scijava.module.ModuleService;
import org.scijava.plugin.Parameter;
import org.scijava.plugin.Plugin;

/**
 * A preprocessor plugin that populates default parameter values.
 * <p>
 * Default values are determined using {@link ModuleService#getDefaultValue}.
 * </p>
 *
 * @author Curtis Rueden
 */
@Plugin(type = PreprocessorPlugin.class, priority = Priority.VERY_HIGH_PRIORITY)
public class DefaultValuePreprocessor extends AbstractPreprocessorPlugin {

	@Parameter
	private ModuleService moduleService;

	// -- ModuleProcessor methods --

	@Override
	public void process(final Module module) {
		for (final ModuleItem<?> input : module.getInfo().inputs()) {
			assignDefaultValue(module, input);
		}
		for (final ModuleItem<?> output : module.getInfo().outputs()) {
			assignDefaultValue(module, output);
		}
	}

	// -- Helper methods --

	private <T> void assignDefaultValue(final Module module,
		final ModuleItem<T> item)
	{
		if (module.isResolved(item.getName())) return;
		final T defaultValue = moduleService.getDefaultValue(item);
		if (defaultValue == null) return;
		item.setValue(module, defaultValue);
	}

}

Add preprocessor that assigns default values
Add preprocessor that assigns default values

Unresolved module items should be assigned their default value,
as given by the ModuleService#getDefaultValue() method, before
anything else (even module initialization!) happens.
