Better document the runWithClient(() => ..., client.call) pattern (#772)

Author: brianquinlan

pkgs/cronet_http/example/lib/main.dart

@@ -8,21 +8,16 @@ import 'dart:io';
 import 'package:cronet_http/cronet_client.dart';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart';
-import 'package:http/io_client.dart';
 
 import 'book.dart';
 
-void main() async {
-  late Client client;
+void main() {
+  var clientFactory = Client.new; // Constructs the default client.
   if (Platform.isAndroid) {
-    client = CronetClient(await CronetEngine.build(
-        cacheMode: CacheMode.memory, cacheMaxSize: 1024 * 1024));
-  } else {
-    client = IOClient();
+    WidgetsFlutterBinding.ensureInitialized();
+    clientFactory = CronetClient.new;
   }
-
-  // Run the app with the default `client` set to the one assigned above.
-  runWithClient(() => runApp(const BookSearchApp()), () => client);
+  runWithClient(() => runApp(const BookSearchApp()), clientFactory);
 }
 
 class BookSearchApp extends StatelessWidget {

pkgs/cupertino_http/example/lib/main.dart

@@ -8,21 +8,15 @@ import 'dart:io';
 import 'package:cupertino_http/cupertino_client.dart';
 import 'package:flutter/material.dart';
 import 'package:http/http.dart';
-import 'package:http/io_client.dart';
 
 import 'book.dart';
 
 void main() {
-  late Client client;
-  // Use Cupertino Http on iOS and macOS.
+  var clientFactory = Client.new; // The default Client.
   if (Platform.isIOS || Platform.isMacOS) {
-    client = CupertinoClient.defaultSessionConfiguration();
-  } else {
-    client = IOClient();
+    clientFactory = CupertinoClient.defaultSessionConfiguration.call;
   }
-
-  // Run the app with the default `client` set to the one assigned above.
-  runWithClient(() => runApp(const BookSearchApp()), () => client);
+  runWithClient(() => runApp(const BookSearchApp()), clientFactory);
 }
 
 class BookSearchApp extends StatelessWidget {

pkgs/http/lib/src/client.dart

@@ -171,8 +171,11 @@ Client? get zoneClient {
 /// }
 ///
 /// void main() {
-///   Client client =  Platform.isAndroid ? MyAndroidHttpClient() : Client();
-///   runWithClient(myFunction, () => client);
+///  var clientFactory = Client.new; // Constructs the default client.
+///  if (Platform.isAndroid) {
+///     clientFactory = MyAndroidHttpClient.new;
+///  }
+///  runWithClient(myFunction, clientFactory);
 /// }
 ///
 /// void myFunction() {
@@ -183,7 +186,8 @@ Client? get zoneClient {
 /// ```
 ///
 /// The [Client] returned by [clientFactory] is used by the [Client.new] factory
-/// and the convenience HTTP functions (e.g. [http.get])
+/// and the convenience HTTP functions (e.g. [http.get]). If [clientFactory]
+/// returns `Client()` then the default [Client] is used.
 R runWithClient<R>(R Function() body, Client Function() clientFactory,
         {ZoneSpecification? zoneSpecification}) =>
     runZoned(body,

pkgs/http/test/io/client_test.dart

@@ -153,6 +153,11 @@ void main() {
     expect(client, isA<TestClient>());
   });
 
+  test('runWithClient Client() return', () {
+    final client = http.runWithClient(() => http.Client(), () => http.Client());
+    expect(client, isA<http_io.IOClient>());
+  });
+
   test('runWithClient nested', () {
     late final http.Client client;
     late final http.Client nestedClient;