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class Animal {
  final String name;
  final double age;

  const Animal({ required this.name, required this.age });
}

class Budgie extends Animal {
  // 旧的语法
  const Budgie({ required String name, required double age })
      : super(name:name, age:age);

  // 新的语法
  const Budgie({ required super.name, required super.age });
}

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class Center extends Align {
  // 改造前
  const Center({ Key? key, double? widthFactor, double? heightFactor, Widget? child })
    : super(key: key, widthFactor: widthFactor, heightFactor: heightFactor, child: child);

  // 改造后
  const Center({ super.key, super.widthFactor, super.heightFactor, super.child });
}

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import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Super Constructor Demo',
      debugShowCheckedModeBanner: false,
      home: Material(
        child: CustomCenter(
          child: Text(
            'Super Constructor Demo',
          ),
        ),
      ),
    );
  }
}

class CustomCenter extends Align {
  // 改造前
  //const Center({ Key? key, double? widthFactor, double? heightFactor, Widget? child })
  //  : super(key: key, widthFactor: widthFactor, heightFactor: heightFactor, child: child);

  // 改造后
  const CustomCenter(
      {super.key, super.widthFactor, super.heightFactor, super.child});
}