pushReplacement<T extends Object, TO extends Object> method

  1. @optionalTypeArgs
Future<T> pushReplacement <T extends Object, TO extends Object>(Route<T> newRoute, { TO result })
@optionalTypeArgs

Replace the current route of the navigator by pushing the given route and then disposing the previous route once the new route has finished animating in.

If non-null, result will be used as the result of the route that is removed; the future that had been returned from pushing that old route will complete with result. Routes such as dialogs or popup menus typically use this mechanism to return the value selected by the user to the widget that created their route. The type of result, if provided, must match the type argument of the class of the old route (TO).

The new route and the route below the removed route are notified (see Route.didPush and Route.didChangeNext). If the Navigator has any Navigator.observers, they will be notified as well (see NavigatorObserver.didReplace). The removed route is notified once the new route has finished animating (see Route.didComplete).

Ongoing gestures within the current route are canceled when a new route is pushed.

Returns a Future that completes to the result value passed to pop when the pushed route is popped off the navigator.

The T type argument is the type of the return value of the new route, and TO is the type of the return value of the old route.

Typical usage is as follows: 
void _doOpenPage() {
  navigator.pushReplacement(
      MaterialPageRoute(builder: (BuildContext context) => MyHomePage()));
}

Implementation 

@optionalTypeArgs
Future<T> pushReplacement<T extends Object, TO extends Object>(Route<T> newRoute, { TO result }) {
  assert(!_debugLocked);
  assert(() { _debugLocked = true; return true; }());
  final Route<dynamic> oldRoute = _history.last;
  assert(oldRoute != null && oldRoute._navigator == this);
  assert(oldRoute.overlayEntries.isNotEmpty);
  assert(newRoute._navigator == null);
  assert(newRoute.overlayEntries.isEmpty);
  final int index = _history.length - 1;
  assert(index >= 0);
  assert(_history.indexOf(oldRoute) == index);
  newRoute._navigator = this;
  newRoute.install(_currentOverlayEntry);
  _history[index] = newRoute;
  newRoute.didPush().whenCompleteOrCancel(() {
    // The old route's exit is not animated. We're assuming that the
    // new route completely obscures the old one.
    if (mounted) {
      oldRoute
        ..didComplete(result ?? oldRoute.currentResult)
        ..dispose();
    }
  });
  newRoute.didChangeNext(null);
  if (index > 0) {
    _history[index - 1].didChangeNext(newRoute);
    newRoute.didChangePrevious(_history[index - 1]);
  }
  for (NavigatorObserver observer in widget.observers)
    observer.didReplace(newRoute: newRoute, oldRoute: oldRoute);
  assert(() { _debugLocked = false; return true; }());
  _afterNavigation();
  return newRoute.popped;
}