Generic types in PopScope

Added a generic type to the PopScope class and replaced the onPopInvoked with a new method onPopInvokedWithResult. The new method takes a boolean didPop and a result as position parameters.

Also replaced the Form.onPopInvoked with Form.onPopInvokedWithResult for the same reason.

Previously, PopScope didn't have a way to access the pop result when onPopInvoked was called. The generic type is added to the PopScope class so that the new method onPopInvokedWithResult can access the type-safe result.

Added a generic type (<T>) to the PopScope class and a new method onPopInvokedWithResult. The onPopInvoked property was deprecated in favor of onPopInvokedWithResult.

Also added a new method onPopInvokedWithResult to Form to replace onPopInvoked.

Code before migration:

import 'package:flutter/material.dart';
​
void main() {
  runApp(
    MaterialApp(
      navigatorKey: nav,
      home: Column(
        children: [
          Form(
            canPop: false,
            onPopInvoked: (bool didPop) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
          PopScope(
            canPop: false,
            onPopInvoked: (bool didPop) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
        ],
      ),
    ),
  );
}

Code after migration:

import 'package:flutter/material.dart';
​
void main() {
  runApp(
    MaterialApp(
      navigatorKey: nav,
      home: Column(
        children: [
          Form(
            canPop: false,
            onPopInvokedWithResult: (bool didPop, Object? result) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
          PopScope<Object?>(
            canPop: false,
            onPopInvokedWithResult: (bool didPop, Object? result) {
              if (didPop) {
                return;
              }
              launchConfirmationDialog();
            },
            child: MyWidget(),
          ),
        ],
      ),
    ),
  );
}

The generic type should match the generic type of the Route that the PopScope is in. For example, if the route uses int as its generic type, consider using PopScope<int>.

If the PopScope widgets are shared across multiple routes with different types, you can use PopScope<Object?> to catch all possible types.

Landed in version: 3.22.0-26.0.pre
In stable release: 3.24.0

API documentation:

• PopScope
• onPopInvoked
• Route
• onPopInvokedWithResult
• Form.onPopInvoked
• Form.onPopInvokedWithResult

Relevant issue:

• Issue 137458

Relevant PR:

• Add generic type for result in PopScope (reverted)
• Reapply new PopScope API (final reland)