Add Part 1

Author: GiancarloCode

Part 1/user.dart

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+class User {
+  final String _id;
+  final String _name;
+
+  String get id => _id;
+  String get name => _name;
+
+  User._({String id, String name})
+      : _id = id,
+        _name = name;
+
+  factory User([void Function(UserBuilder) updates]) =>
+      (UserBuilder()..update(updates)).build();
+
+  User rebuild(void Function(UserBuilder) updates) =>
+      (toBuilder()..update(updates)).build();
+
+  UserBuilder toBuilder() => UserBuilder()..replace(this);
+
+  @override
+  bool operator ==(Object other) {
+    if (identical(other, this)) return true;
+    return other is User && id == other.id && name == other.name;
+  }
+
+  @override
+  int get hashCode => id.hashCode ^ name.hashCode;
+
+  @override
+  String toString() => '''User {
+  id=$id,
+  name=$name,
+}''';
+}
+
+class UserBuilder {
+  User _user;
+
+  String _id;
+  String get id => _user != null ? _user._id : _id;
+  set id(String id) => _this._id = id;
+
+  String _name;
+  String get name => _user != null ? _user._name : _name;
+  set name(String name) => _this._name = name;
+
+  UserBuilder get _this {
+    if (_user != null) {
+      _id = _user.id;
+      _name = _user.name;
+      _user = null;
+    }
+    return this;
+  }
+
+  UserBuilder();
+
+  void replace(User other) {
+    if (other == null) {
+      throw ArgumentError.notNull('other');
+    }
+    _user = other;
+  }
+
+  void update(void Function(UserBuilder) updates) {
+    if (updates != null) updates(this);
+  }
+
+  User build() {
+    final result = _user ?? User._(id: id, name: name);
+    replace(result);
+    _this;
+    return result;
+  }
+}

README.MD

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+# Built Value and Built Collections Example
+
+Repositorio de la serie de vídeos donde te enseño a dominar el paquete [built_value](https://github.com/google/built_value.dart).
+
+# Tutoriales de YouTube
+
+- [Parte 1 - Tipos de Valor Inmutables (Inmutable Value Types)](https://www.youtube.com/watch?v=oVNP1Kx4irw)
+