Merge branch 'command-default-values'

This makes the getDefaultValue() method work for Command modules.

This branch is dedicated to Christian Dietz.

Author: ctrueden

src/main/java/org/scijava/command/CommandModuleItem.java

@@ -143,6 +143,38 @@ public T getMaximumValue() {
 		return tValue(getParameter().max());
 	}
 
+	@Override
+	public T getDefaultValue() {
+		// NB: The default value for a command is the initial field value.
+		// E.g.:
+		//
+		//   @Parameter
+		//   private int weekdays = 5;
+		//
+		// To obtain this information, we need to instantiate the module, then
+		// extract the value of the associated field.
+		//
+		// Of course, the command might do evil things like:
+		//
+		//   @Parameter
+		//   private long time = System.currentTimeMillis();
+		//
+		// In which case the default value will vary by instance. But there is
+		// nothing we can really do about that. This is only a best effort.
+
+		try {
+			final Object dummy = getInfo().loadDelegateClass().newInstance();
+			@SuppressWarnings("unchecked")
+			final T value = (T) getField().get(dummy);
+			return value;
+		}
+		catch (final InstantiationException | IllegalAccessException
+				| ClassNotFoundException exc)
+		{
+			throw new IllegalStateException(exc);
+		}
+	}
+
 	@Override
 	public Number getStepSize() {
 		// FIXME: stepSize should be typed on T, not Number!

src/test/java/org/scijava/command/CommandModuleTest.java

@@ -43,6 +43,7 @@
 import org.scijava.module.Module;
 import org.scijava.module.process.AbstractPreprocessorPlugin;
 import org.scijava.module.process.PreprocessorPlugin;
+import org.scijava.plugin.Parameter;
 import org.scijava.plugin.Plugin;
 
 /** Regression tests for {@link CommandModule}. */
@@ -76,6 +77,25 @@ public void testNotCancelable() throws InterruptedException,
 		assertEquals("NO SINGING!", fire.getCancelReason());
 	}
 
+	@Test
+	public void testDefaultValues() {
+		final Context context = new Context(CommandService.class);
+		final CommandService commandService = context.service(CommandService.class);
+		final CommandInfo info = //
+			commandService.getCommand(CommandWithDefaultValues.class);
+
+		assertEquals(5, info.getInput("weekdays").getDefaultValue());
+
+		final long defaultTime = (Long) info.getInput("time").getDefaultValue();
+		final long timeDiff = System.currentTimeMillis() - defaultTime;
+		assertTrue(timeDiff >= 0 && timeDiff < 50); // 50 ms should be enough ;-)
+
+		final String defaultName = (String) info.getInput("name").getDefaultValue();
+		assertEquals("John Jacob Jingleheimer Schmidt", defaultName);
+
+		assertEquals(null, info.getInput("thing").getDefaultValue());
+	}
+
 	// -- Helper classes --
 
 	/** A command which implements {@link Cancelable}. */
@@ -125,4 +145,27 @@ public void process(final Module module) {
 			}
 		}
 	}
+
+	/** A command which assigns default values to its parameters. */
+	@Plugin(type = Command.class)
+	public static class CommandWithDefaultValues extends ContextCommand {
+
+		@Parameter
+		private int weekdays = 5;
+
+		@Parameter
+		private long time = System.currentTimeMillis();
+
+		@Parameter
+		private String name = "John Jacob Jingleheimer Schmidt";
+
+		@Parameter
+		private Object thing;
+
+		@Override
+		public void run() {
+			weekdays = 0;
+			time = 0;
+		}
+	}
 }