flutter provider what is the difference with 'Context context' and 'context ' - flutter

Question

```
import 'package:a_class_flutter/provider/ac_score/ac_score_provider.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';
import 'package:provider/provider.dart';
class ACScoreView extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (context) => ACScoreProvider(),
builder: (context, child) {
return Stack(
children: <Widget>[
_topMenu(context),
],
);
},
);
}
}
// Important!
Widget _topMenu(BuildContext context) {
return GestureDetector(
onTap: () {
context.read<ACScoreProvider>().showTopMenueStatus();
},
child: Container(
width: double.infinity,
height: double.infinity,
color: Colors.red,
child: Stack(
children: <Widget>[
Positioned(
child: AnimatedOpacity(
duration: Duration(microseconds: 100),
opacity:
context.watch<ACScoreProvider>().needShowTopMenue ? 1.0 : 0.0,
child: Container(
width: double.infinity,
height: ScreenUtil().setHeight(60),
color: Colors.black,
),
),
)
],
),
),
);
}
```
This is my code which is working well, but when I try to change Widget _topMenu(BuildContext context) to Widget _topMenu(context), Flutter gives me an error which is:
The following NoSuchMethodError was thrown building Builder(dirty, dependencies: [_InheritedProviderScope<ACScoreProvider>]): Class 'StatelessElement' has no instance method 'watch'. Receiver: Instance of 'StatelessElement'. Tried calling: watch<ACScoreProvider>().The relevant error-causing widget was ChangeNotifierProvider<ACScoreProvider> package:a_class_flutter/…/ac_score/ac_score.dart:9.
Why missing BuildContext declaration could cause this error? Do I need to put every context with BuildContext?

Answer 1

From the provider docs:
The easiest way to read a value is by using the extension methods on [BuildContext]:
context.read<T>(), which returns T without listening to it
Writing just Widget _topMenu(context), the context parameter is inferred as a dynamic context not BuildContext context and hence you it does not have the extension method .read<T>() you are trying to call.
If it were inside a StatefulWidget, this wouldn't have been a problem because it's State class has a instance context (type BuildContext) property and so the extension method .read<T>() can be called on it.