rpc example for directory file listing

samples/rpc/dir_sample.dart

+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+
+/**
+ * This is a very simple sample app showing how to use the DirectoryProxy
+ * interface.  (See comments on DirectoryProxy for more explanation.)
+ *
+ * In this sample, we list the files in the directory that
+ * is supplied on the command line.
+ *
+ * Then, we attempt to list the files in a directory that doesn't exist
+ * (that is to show how exceptions pass back through the RPC
+ * system).
+ */
+
+void main() {
+  if (new Options().arguments.length < 1) {
+    print("usage: out/Debug_ia32/dart_bin --enable_type_checks --enable_asserts dir_sample.dart <path>");
+    return;
+  }
+
+  String path = new Options().arguments[0];
+
+  DirectoryProxy dir = DirectoryProxy.create(path);
+
+  dir.isDirectory().then((bool isDir) {
+    if (isDir) {
+      print("${dir} is a directory, and contains these files");
+      dir.list().then((List<String> names) {
+        for (String name in names) {
+          print("found file ${name}");
+        }
+      });
+    } else {
+      print("${dir} is not a directory");
+    }
+  });
+
+  // Here we deliberately use a bad path to show how an exception that
+  // is thrown in the service isolate will be pass back through
+  // the RPC system and can be caught in the main isolate.
+  //
+  // TODO(mattsh) - need a way to install a global exception handler
+  // for an isolate.
+
+  String badPath = "/path/that/does/not/exist";
+
+  print("an exception is expected here");
+  DirectoryProxy.create(badPath).list().then((List<String> names) {
+    // won't reach here because an exception will be thrown
+    assert(false);
+  });
+}