Fix #92: rewrite samples using async await.

dart_io_mini_samples/example/files_directories_and_symlinks/deleting_a_file_directory_or_symlink.dart

@@ -5,20 +5,19 @@
 /// Use the FilesSystemEntity `delete()` method to delete a file, directory, or
 /// symlink. This method is inherited by File, Directory, and Link.
 
-
 import 'dart:io';
 
-void main() {
+main() async {
+
   // Create a temporary directory.
-  Directory.systemTemp.createTemp('my_temp_dir')
-    .then((directory) {
-      // Confirm it exists.
-      directory.exists().then(print); // Prints 'true'.
-      // Delete the directory.
-      return directory.delete();
-    })
-    .then((directory) {
-      // Confirm it no longer exists.
-      directory.exists().then(print); // Prints 'false'
-    });
+  var dir = await Directory.systemTemp.createTemp('my_temp_dir');
+
+  // Confirm it exists.
+  print(await dir.exists());
+
+  // Delete the directory.
+  await dir.delete();
+
+  // Confirm it no longer exists.
+  print(await dir.exists());
 }

dart_io_mini_samples/example/files_directories_and_symlinks/directories/creating_a_directory.dart

@@ -8,11 +8,8 @@
 
 import 'dart:io';
 
-void main() {
+main() async {
   // Creates dir/ and dir/subdir/.
-  new Directory('dir/subdir').create(recursive: true)
-    // The created directory is returned as a Future.
-    .then((Directory directory) {
-      print(directory.path);
-  });
-}
+  var directory = await new Directory('dir/subdir').create(recursive: true);
+  print(directory.path);
+}

dart_io_mini_samples/example/files_directories_and_symlinks/directories/creating_a_temporary_directory.dart

@@ -8,10 +8,7 @@
 
 import 'dart:io';
 
-void main() {
-  // Create a temporary directory in the system temp directory.
-  Directory.systemTemp.createTemp('my_temp_dir')
-    .then((directory) {
-      print(directory.path);
-    });
+main() async {
+  var directory = await Directory.systemTemp.createTemp('my_temp_dir');
+  print(directory.path);
 }

dart_io_mini_samples/example/files_directories_and_symlinks/directories/listing_the_contents_of_a_directory.dart

@@ -8,15 +8,15 @@
 /// `false` (default is `true`).
 
 import 'dart:io';
+import 'dart:async'; // Import not needed but added here to explicitly assign type for clarity below.
 
-void main() {
+main() async {
   // Get the system temp directory.
   var systemTempDir = Directory.systemTemp;
 
   // List directory contents, recursing into sub-directories, but not following
   // symbolic links.
-  systemTempDir.list(recursive: true, followLinks: false)
-    .listen((FileSystemEntity entity) {
-      print(entity.path);
-    });
+  Stream<FileSystemEntity> entityList =
+      systemTempDir.list(recursive: true, followLinks: false);
+  await for (FileSystemEntity entity in entityList) print(entity.path);
 }

dart_io_mini_samples/example/files_directories_and_symlinks/files/creating_a_file.dart

@@ -8,16 +8,13 @@
 
 import 'dart:io';
 
-void main() {
+main() async {
 
   // Get the system temp directory.
   var systemTempDir = Directory.systemTemp;
-
   // Creates dir/, dir/subdir/, and dir/subdir/file.txt in the system
   // temp directory.
-  new File('${systemTempDir.path}/dir/subdir/file.txt').create(recursive: true)
-    // The created file is returned as a Future.
-    .then((file) {
-      print(file.path);
-  });
-}
+  var file = await new File('${systemTempDir.path}/dir/subdir/file.txt').create(
+      recursive: true);
+  print(file.path);
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/handling_errors_when_reading_a_file.dart

@@ -2,24 +2,15 @@
 // 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.
 
-/// Use `then()` to read the file contents, and `catchError()` to catch
-/// errors. Register a callback with `catchError()` to handle the error.
-
 import 'dart:io';
 
-void handleError(e) {
-  print('There was a ${e.runtimeType} error');
-  print(e.message);
-}
-
-main() {
+main() async {
   final filename = 'non_existent_file.txt';
-  new File(filename).readAsString()
-    // Read and print the file contents.
-    .then(print)
-    // Catch errors.
-    .catchError((e) {
-      print('There was a ${e.runtimeType} error');
-      print('Could not read $filename');
-    });
-}
+  try {
+    var file = await new File(filename).readAsString();
+    print(file);
+  } catch (e) {
+    print('There was a ${e.runtimeType} error');
+    print('Could not read $filename');
+  }
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/reading_a_file_as_a_string.dart

@@ -6,8 +6,7 @@
 
 import 'dart:io';
 
-void main() {
-  new File('file.txt').readAsString().then((String contents) {
-    // Do something with the file contents.
-  });
-}
+main() async {
+  var contents = await new File('file.txt').readAsString();
+  print(contents);
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/reading_a_file_as_bytes.dart

@@ -8,10 +8,9 @@ import 'dart:io';
 
 import 'package:crypto/crypto.dart';
 
-void main() {
-  new File('file.txt').readAsBytes().then((bytes) {
-    // Do something with the bytes. For example, convert to base64.
-    String base64 = CryptoUtils.bytesToBase64(bytes);
-    // ...
-  });
-}
+main() async {
+  var bytes = await new File('file.txt').readAsBytes();
+  // Do something with the bytes. For example, convert to base64.
+  String base64 = CryptoUtils.bytesToBase64(bytes);
+  print(base64);
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/reading_a_file_as_lines.dart

@@ -6,8 +6,7 @@
 
 import 'dart:io';
 
-void main() {
-  new File('file.txt').readAsLines().then((List<String> lines) {
-    // Do something with lines.
-  });
-}
+main() async {
+  List<String> lines = await new File('file.txt').readAsLines();
+  lines.forEach((String line) => print(line));
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/reading_a_file_using_a_stream.dart

@@ -13,19 +13,21 @@ import 'dart:io';
 import 'dart:convert';
 import 'dart:async';
 
-main() {
+main() async {
   final file = new File('file.txt');
   Stream<List<int>> inputStream = file.openRead();
 
-  inputStream
-    // Decode to UTF8.
-    .transform(UTF8.decoder)
-    // Convert stream to individual lines.
-    .transform(new LineSplitter())
-    // Process results.
-    .listen((String line) {
-        print('$line: ${line.length} bytes');
-      },
-      onDone: () { print('File is now closed.'); },
-      onError: (e) { print(e.toString()); });
-}
+  Stream<String> lines = inputStream
+      // Decode to UTF8.
+      .transform(UTF8.decoder)
+      // Convert stream to individual lines.
+      .transform(new LineSplitter());
+
+  try {
+    await for (String line in lines) print('$line: ${line.length} bytes');
+  } catch (e) {
+    print(e.toString());
+  }
+
+  print('File is now closed.');
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/writing_a_string_to_a_file.dart

@@ -7,10 +7,8 @@
 
 import 'dart:io';
 
-void main() {
+main() async {
   final filename = 'file.txt';
-  new File(filename).writeAsString('some content')
-    .then((File file) {
-      // Do something with the file.
-    });
-}
+  var file = await new File(filename).writeAsString('some content');
+  print("Content written to $file");
+}

dart_io_mini_samples/example/files_directories_and_symlinks/files/writing_bytes_to_a_file.dart

@@ -7,16 +7,15 @@
 import 'dart:io';
 import 'dart:convert';
 
-void main() {
+main() async {
   final string = 'Dart!';
+
   // Encode to UTF8.
   var encodedData = UTF8.encode(string);
+  var file = await new File('file.txt');
+  file.writeAsBytes(encodedData);
+  var data = await file.readAsBytes();
 
-  new File('file.txt')
-    .writeAsBytes(encodedData)
-    .then((file) => file.readAsBytes())
-    .then((data) {
-      // Decode to a string, and print.
-      print(UTF8.decode(data)); // Prints 'Dart!'.
-  });
+  // Decode to a string, and print.
+  print(UTF8.decode(data)); // Prints 'Dart!'.
 }

dart_io_mini_samples/example/files_directories_and_symlinks/files/writing_to_a_file_using_a_stream.dart

@@ -9,11 +9,11 @@
 
 import 'dart:io';
 
-void main() {
+main() {
   var file = new File('file.txt');
   var sink = file.openWrite();
   sink.write('FILE ACCESSED ${new DateTime.now()}\n');
 
   // Close the IOSink to free system resources.
   sink.close();
-}
+}

dart_io_mini_samples/example/files_directories_and_symlinks/finding_the_type_of_a_filesystem_object.dart

@@ -6,30 +6,32 @@
 /// object. This method is inherited by File, Directory, and Link.
 
 import 'dart:io';
+import 'dart:async'; // Import not needed but added here to explicitly assign type for clarity below.
 
-void main() {
+main() async {
   // List the contents of the system temp directory.
-  Directory.systemTemp.list(recursive: true, followLinks: false)
-    .listen((FileSystemEntity entity) {
-      // Get the type of the FileSystemEntity, apply the appropiate label, and
-      // print the entity path.
-      FileSystemEntity.type(entity.path)
-        .then((FileSystemEntityType type) {
-          String label;
-          switch (type) {
-            case FileSystemEntityType.DIRECTORY:
-              label = 'D';
-              break;
-            case FileSystemEntityType.FILE:
-              label = 'F';
-              break;
-            case FileSystemEntityType.LINK:
-              label = 'L';
-              break;
-            default:
-              label = 'UNKNOWN';
-          }
-          print('$label: ${entity.path}');
-      });
-    });
-}
+  Stream<FileSystemEntity> entityList =
+      Directory.systemTemp.list(recursive: true, followLinks: false);
+
+  await for (FileSystemEntity entity in entityList) {
+    // Get the type of the FileSystemEntity, apply the appropiate label, and
+    // print the entity path.
+    FileSystemEntityType type = await FileSystemEntity.type(entity.path);
+
+    String label;
+    switch (type) {
+      case FileSystemEntityType.DIRECTORY:
+        label = 'D';
+        break;
+      case FileSystemEntityType.FILE:
+        label = 'F';
+        break;
+      case FileSystemEntityType.LINK:
+        label = 'L';
+        break;
+      default:
+        label = 'UNKNOWN';
+    }
+    print('$label: ${entity.path}');
+  }
+}

dart_io_mini_samples/example/files_directories_and_symlinks/getting_the_parent_directory.dart

@@ -7,12 +7,12 @@
 /// and Link.
 
 import 'dart:io';
+import 'dart:async'; // Import not needed but added here to explicitly assign type for clarity below.
 
-void main() {
+main() async {
   // List the contents of the system temp directory.
-  Directory.systemTemp.list(recursive: true, followLinks: false)
-    .listen((FileSystemEntity entity) {
-      // Print the path of the parent of each file, directory, and symlink.
-      print(entity.parent.path);
-    });
-}
+  Stream<FileSystemEntity> entityList =
+      Directory.systemTemp.list(recursive: true, followLinks: false);
+
+  await for (FileSystemEntity entity in entityList) print(entity.parent.path);
+}

dart_io_mini_samples/example/files_directories_and_symlinks/renaming_a_file_directory_or_symlink.dart

@@ -8,18 +8,19 @@
 
 import 'dart:io';
 
-void main() {
+main() async {
   // Get the system temp directory.
   var systemTempDir = Directory.systemTemp;
 
   // Create a file.
-  new File('${systemTempDir.path}/foo.txt').create()
-    .then((file) {
-      print('The path is ${file.path}'); // Prints path ending with `foo.txt`.
-      // Rename the file.
-      return file.rename('${systemTempDir.path}/bar.txt');
-    })
-    .then((file) {
-      print('The path is ${file.path}'); // Prints path ending with `bar.txt`.
-    });
-}
+  var file = await new File('${systemTempDir.path}/foo.txt').create();
+
+  // Prints path ending with `foo.txt`.
+  print('The path is ${file.path}');
+
+  // Rename the file.
+  await file.rename('${systemTempDir.path}/bar.txt');
+
+  // Prints path ending with `bar.txt`.
+  print('The path is ${file.path}');
+}