Dart多个构造函数

您只能有一个 未命名的 构造函数，但可以有任意数量的其他已 命名的
构造函数

class Player {  Player(String name, int color) {    this._color = color;    this._name = name;  }  Player.fromPlayer(Player another) {    this._color = another.getColor();    this._name = another.getName();  }  }new Player.fromPlayer(playerOne);

该构造函数可以简化

  Player(String name, int color) {    this._color = color;    this._name = name;  }

至

  Player(this._name, this._color);

命名构造函数也可以通过以

_

class Player {  Player._(this._name, this._color);  Player._foo();}

具有

final

class Player {  final String name;  final String color;  Player(this.name, this.color);  Player.fromPlayer(Player another) :    color = another.color,    name = another.name;}