Defining a variable in Dart/Flutter and referencing parent context - dart

Question

Suppose I have an AppBar:
final AppBar myAppBar = AppBar(
leading: IconButton(
icon: Icon(Icons.delete),
onPressed: () {},
),
);
If I want to reference the main parent context in that onPressed function, is there a way to reference the variable without creating a new class or creating a function which takes the context as an argument for constructing a new component?
final AppBar myAppBar = AppBar(
leading: IconButton(
icon: Icon(Icons.delete),
onPressed: () { print(this.context); },
),
);

Answer 1

You said the parent Widget was a MaterialApp, so in order to access the BuildContext of a parent Widget, you can use the BuildContext of the child Widget in the following way:
class Foo extends StatefulWidget {
...
}
class FooState extends State<Foo> {
...
BuildContext getParentContext() {
return context.ancestorStateOfType(const TypeMatcher<MaterialApp>()).context;
}
}
If you don't have access to the child's BuildContext, then you have 2 other options:
Passing a callback which gives the parent's BuildContext when the child requires it:
class FooParent extends StatelessWidget {
...
#override
Widget build(BuildContext context) {
return Foo(onProvideParentContext: () => context);
}
}
typedef ContextProvider = BuildContext Function();
class Foo extends StatefulWidget {
final ContextProvider onProvideParentContext;
Foo({
#required this.onProvideParentContext,
});
...
}
class FooState extends State<Foo> {
...
BuildContext getParentContext() {
return widget.onProvideParentContext();
}
}
Passing the BuildContext directly to the child as a parameter.
class FooParent extends StatelessWidget {
...
#override
Widget build(BuildContext context) {
return Foo(parentContext: context);
}
}
class Foo extends StatefulWidget {
final BuildContext parentContext;
Foo({
#required this.parentContext,
});
...
}
class FooState extends State<Foo> {
...
BuildContext getParentContext() {
return widget.parentContext;
}
}

Answer 2

After some digging, I came across Builder and StatefulBuilder in the Flutter API documentation:
https://api.flutter.dev/flutter/widgets/Builder-class.html
https://api.flutter.dev/flutter/widgets/StatefulBuilder-class.html
final AppBar myAppBar = AppBar(
leading: IconButton(
icon: Icon(Icons.delete),
onPressed: () { print(this.context); },
),
);
Would become:
final AppBar myAppBar = AppBar(
leading: Builder(
builder: (BuildContext context) => IconButton(
icon: Icon(Icons.delete),
onPressed: () { print(context); },
),
),
);
or, if I need state:
int totalClicks = 0;
final PreferredSizeWidget myAppBar = PreferredSize(
preferredSize: Size.fromHeight(50.0),
child: StatefulBuilder(
builder: (
BuildContext context,
StateSetter setState,
) {
return AppBar(
leading: IconButton(
icon: Icon(Icons.thumb_up),
onPressed: () => setState(() => totalClicks++),
),
title: Text('Clicked: $totalClicks times!')
);
}
),
);