Initial commit

lib/network/res.dart

@@ -0,0 +1,39 @@
+import 'package:flutter/cupertino.dart';
+
+@immutable
+class Res<T>{
+  ///error info
+  final String? errorMessage;
+
+  String get errorMessageWithoutNull => errorMessage??"Unknown Error";
+
+  /// data
+  final T? _data;
+
+  /// is there an error
+  bool get error => errorMessage!=null || _data==null;
+
+  /// whether succeed
+  bool get success => !error;
+
+  /// data
+  ///
+  /// must be called when no error happened, or it will throw error
+  T get data => _data ?? (throw Exception(errorMessage));
+
+  /// get data, or null if there is an error
+  T? get dataOrNull => _data;
+
+  final dynamic subData;
+
+  @override
+  String toString() => _data.toString();
+
+  Res.fromErrorRes(Res another, {this.subData}):
+        _data=null,errorMessage=another.errorMessageWithoutNull;
+
+  /// network result
+  const Res(this._data,{this.errorMessage, this.subData});
+
+  Res.error(dynamic e):errorMessage=e.toString(), _data=null, subData=null;
+}