Context: add ctor arg for strict service handling

By default, strict mode is enabled. But you can pass strict=false
if you want context creation to continue (rather than throwing
IllegalArgumentException) even when a required service fails to
instantiate.

Author: ctrueden

src/main/java/org/scijava/Context.java

@@ -122,6 +122,21 @@ public Context(final Collection<Class<? extends Service>> serviceClasses) {
 		this(serviceClasses, null);
 	}
 
+	/**
+	 * Creates a new SciJava application context with the specified services (and
+	 * any required service dependencies).
+	 * 
+	 * @param serviceClasses A collection of types that implement the
+	 *          {@link Service} interface (e.g., {@code DisplayService.class}).
+	 * @param strict Whether context creation will fail fast when there is
+	 *          is an error instantiating a required service.
+	 */
+	public Context(final Collection<Class<? extends Service>> serviceClasses,
+		final boolean strict)
+	{
+		this(serviceClasses, null, strict);
+	}
+
 	/**
 	 * Creates a new SciJava application with the specified PluginIndex. This
 	 * allows a base set of available plugins to be defined, and is useful when
@@ -140,6 +155,27 @@ public Context(final PluginIndex pluginIndex) {
 		this(Arrays.<Class<? extends Service>> asList(Service.class), pluginIndex);
 	}
 
+	/**
+	 * Creates a new SciJava application context with the specified services (and
+	 * any required service dependencies). Service dependency candidates are
+	 * selected from those discovered by the given {@link PluginIndex}'s
+	 * associated {@link org.scijava.plugin.PluginFinder}.
+	 * 
+	 * @param serviceClasses A collection of types that implement the
+	 *          {@link Service} interface (e.g., {@code DisplayService.class}).
+	 * @param pluginIndex The plugin index to use when discovering and indexing
+	 *          plugins. If you wish to completely control how services are
+	 *          discovered (i.e., use your own
+	 *          {@link org.scijava.plugin.PluginFinder} implementation), then you
+	 *          can pass a custom {@link PluginIndex} here. Passing null will
+	 *          result in a default plugin index being constructed and used.
+	 */
+	public Context(final Collection<Class<? extends Service>> serviceClasses,
+		final PluginIndex pluginIndex)
+	{
+		this(serviceClasses, pluginIndex, strict());
+	}
+
 	/**
 	 * Creates a new SciJava application context with the specified services (and
 	 * any required service dependencies). Service dependency candidates are
@@ -163,16 +199,19 @@ public Context(final PluginIndex pluginIndex) {
 	 *          {@link org.scijava.plugin.PluginFinder} implementation), then you
 	 *          can pass a custom {@link PluginIndex} here. Passing null will
 	 *          result in a default plugin index being constructed and used.
+	 * @param strict Whether context creation will fail fast when there is
+	 *          is an error instantiating a required service.
 	 */
 	public Context(final Collection<Class<? extends Service>> serviceClasses,
-		final PluginIndex pluginIndex)
+		final PluginIndex pluginIndex, final boolean strict)
 	{
 		serviceIndex = new ServiceIndex();
 
 		this.pluginIndex = pluginIndex == null ? new PluginIndex() : pluginIndex;
 		this.pluginIndex.discover();
 
-		final ServiceHelper serviceHelper = new ServiceHelper(this, serviceClasses);
+		final ServiceHelper serviceHelper =
+			new ServiceHelper(this, serviceClasses, strict);
 		serviceHelper.loadServices();
 	}
 
@@ -353,4 +392,8 @@ private String createMissingServiceMessage(
 		return msg.toString();
 	}
 
+	private static boolean strict() {
+		return true;
+	}
+
 }