英文:
How to pass an object AND a callback to a Stateless Widget in Flutter?
问题
我需要将一个对象和回调一起传递给一个无状态小部件，但无法成功，有人可以帮忙吗？
child: NewPage(rec, onSelectParam: (int param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage(this.rec, this.onSelectParam);
var rec;
Function(int) onSelectParam;
}
它会出现编译错误：
位置参数不足：需要2个，但只提供了1个。
英文:
I need to pass an object together with a Call Back to a stateless widget but fail to do so, can anyone help?
child: NnewPage(rec, onSelectParam: (int param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage(this.rec, this.onSelectParam);
var rec;
Function(int) onSelectParam;
It gives compile error:
> Too few positional arguments: 2 required, 1 given.
答案1
得分: 0
有2种方法：
child: NnewPage(rec, (param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage(this.rec, this.onSelectParam);
var rec;
Function(int) onSelectParam;
}
或者：
child: NnewPage(rec: rec, onSelectParam: (param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage({this.rec, this.onSelectParam});
var rec;
Function(int) onSelectParam;
}
更多详细信息，请参阅这篇文章：https://stackoverflow.com/questions/61947930/understanding-brackets-in-dart
英文:
There are 2 ways:
child: NnewPage(rec, (param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage(this.rec, this.onSelectParam);
var rec;
Function(int) onSelectParam;
or:
child: NnewPage(rec: rec, onSelectParam: (param) {
print('value: ' + param.toString());
})
class NewPage extends StatelessWidget {
NewPage({this.rec, this.onSelectParam});
var rec;
Function(int) onSelectParam;
For more detail, you can read this article: https://stackoverflow.com/questions/61947930/understanding-brackets-in-dart
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