Class 如何向Dart中的现有类添加构造函数?
我想为一些常见的UI类提供一些便利/工厂构造函数。例如,TextStyle:Class 如何向Dart中的现有类添加构造函数?,class,constructor,dart,Class,Constructor,Dart,我想为一些常见的UI类提供一些便利/工厂构造函数。例如,TextStyle: enum Font { AvenirNext, AvenirNextCondensed } enum Weight { Regular, Medium, DemiBold, Bold } // Use: // TextStyle(Fonts.AvenirNext, Weight.Medium, 20, Colors.white) // Maybe it can be even shorte
enum Font {
AvenirNext,
AvenirNextCondensed
}
enum Weight {
Regular,
Medium,
DemiBold,
Bold
}
// Use:
// TextStyle(Fonts.AvenirNext, Weight.Medium, 20, Colors.white)
// Maybe it can be even shorter?
// TextStyle(AvenirNext, Medium, 20, Colors.black)
如何在Dart中实现这一点?像下面这样扩展TextStyle怎么样
class Font {
static const AvenirNext = 'AvenirNext';
static const AvenirNextCondensed = 'AvenirNextCondensed';
}
class Weight{
static const Regular = FontWeight.w400;
static const Medium = FontWeight.w500;
static const DemiBold = FontWeight.w700;
static const Bold = FontWeight.w900;
}
class CTextStyle extends TextStyle {
CTextStyle(String f, FontWeight w, num s, Color c)
: super(
fontFamily: f,
fontWeight: w,
fontSize: s.toDouble(),
color: c);
}
}
用法:
TextStyle myCustom = CTextStyle(Font.AvenirNext, Weight.Medium, 20, Colors.black);
或者,甚至不创建类,只定义创建TextStyle对象的顶级工厂函数。是的,很好。我试图解释我们不能修改这个类。我们只能扩展它。这太棒了。为了学术起见,如果我保留枚举并为超级构造函数构造参数列表:类TSExt扩展TextStyle{//TSExtFont-font-font,Weight-Weight,double-fontSize,Color-Color:superarguments;TSExtFont-Weight,double-fontSize,Color-Color{var-args={//…};superargs;}@GoldenJow这似乎是个好主意,如果您测试了这种方法,请告诉我们