StatefulValueBuilder<T, E extends Object> typedef

StatefulValueBuilder<T, E extends Object> = Widget Function(T value, bool inProgress, {E? error})

Builds UI when StatefulData contains a usable value.

The callback receives:

• value — the current usable value.
• inProgress — true when the value is shown while another operation is still running, for example Loading(prev) or Updating(value).
• error — an optional named parameter. It is provided when the current state is Failure(prev, failure), meaning the old value can still be shown while the latest operation failed.

Important: error is a named callback parameter. The builder must be written with {error}:

builder: (user, inProgress, {error}) {
  return UserView(
    user: user,
    isRefreshing: inProgress,
    errorBanner: error,
  );
}

Do not write it as a third positional parameter:

// Wrong:
builder: (user, inProgress, error) {
  return UserView(user: user);
}

Implementation

typedef StatefulValueBuilder<T, E extends Object> = Widget Function(
    T value,
    bool inProgress, {
    E? error,
    });