added function to get a configuration property without binding to Guice explicitly

core/src/main/java/org/jclouds/config/ValueOfConfigurationKeyOrNull.java

@@ -0,0 +1,55 @@
+/**
+ *
+ * Copyright (C) 2011 Cloud Conscious, LLC. <info@cloudconscious.com>
+ *
+ * ====================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ====================================================================
+ */
+package org.jclouds.config;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import com.google.common.base.Function;
+import com.google.inject.ConfigurationException;
+import com.google.inject.Injector;
+import com.google.inject.Key;
+import com.google.inject.name.Names;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Singleton
+public class ValueOfConfigurationKeyOrNull implements Function<String, String> {
+   protected final Injector injector;
+
+   @Inject
+   public ValueOfConfigurationKeyOrNull(Injector injector) {
+      this.injector = checkNotNull(injector, "injector");
+   }
+
+   @Override
+   public String apply(String configurationKey) {
+      checkNotNull(configurationKey, "configurationKey");
+      try {
+         return injector.getInstance(Key.get(String.class, Names.named(configurationKey)));
+      } catch (ConfigurationException e) {
+         return null;
+      }
+   }
+
+}

core/src/test/java/org/jclouds/config/ValueOfConfigurationKeyOrNullTest.java

@@ -0,0 +1,57 @@
+/**
+ *
+ * Copyright (C) 2011 Cloud Conscious, LLC. <info@cloudconscious.com>
+ *
+ * ====================================================================
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * ====================================================================
+ */
+package org.jclouds.config;
+
+import static org.testng.Assert.assertEquals;
+
+import java.util.concurrent.ExecutionException;
+
+import org.testng.annotations.Test;
+
+import com.google.inject.AbstractModule;
+import com.google.inject.Guice;
+import com.google.inject.name.Names;
+
+/**
+ * Tests behavior of ValueOfConfigurationKeyOrNull
+ * 
+ * @author Adrian Cole
+ */
+@Test(groups = "unit")
+public class ValueOfConfigurationKeyOrNullTest {
+
+   @Test
+   public void testNotThere() throws InterruptedException, ExecutionException {
+      assertEquals(new ValueOfConfigurationKeyOrNull(Guice.createInjector()).apply("foo"), null);
+   }
+
+   @Test
+   public void testThere() throws InterruptedException, ExecutionException {
+      assertEquals(new ValueOfConfigurationKeyOrNull(Guice.createInjector(new AbstractModule() {
+
+         @Override
+         protected void configure() {
+            bindConstant().annotatedWith(Names.named("foo")).to("bar");
+         }
+
+      })).apply("foo"), "bar");
+
+   }
+
+}