Best way to get value from future in constructor in dart

Question

what ways you suggest for getting value from future in object constructor ?

class F{
late SomeObj<t> _obj;
F(){
 () async{
    _obj = await someFuture();
  }.call();
}
 somefunc() => doing something with _obj

}

but this doesn't gave me right res in the right time, Other ways for this situation?

Answer 1

Here are two possible approaches:

• Make your class's constructor private and force callers to instantiate your class via an asynchronous static method. From the perspective of callers, there is little difference between calling a static method and a named constructor.

  class F {
    late SomeObj<T> _obj;
  
    F._();
  
    static Future<F> create() async {
      var f = F._();
      f._obj = await someFuture();
      return f;
    }
  
    Object? someFunc() => doSomethingWith(_obj);
  }
  

• Explicitly make everything that depends on the asynchronous value also asynchronous. If _obj is initialized asynchronously, then _obj should be a Future. If someFunc depends on _obj, then someFunc should return a Future.

  class F {
    Future<SomeObj<T>> _obj;
  
    F() : _obj = someFuture();
  
    Future<Object?> someFunc() async => doSomethingWith(await _obj);
  }