How to tell if an object is an instance of a class

Question

How can I determine whether an object is of a class or not in the Dart language?

I'm looking to do something like the following:

if (someObject.class.toString() == "Num") {
    ...
}

And what is the returned value type? Will it have to be a String?

---

The mirror library has been up and down and seems to be subject to rapid change right now, as the one thing I did find simply did not work as shown.

Answer 1

• By using the is and is! operators, like this:

  if (someObject is T)
  

  From the documentation:

  The is and is! operators are handy for checking types. The result of obj is T is true if obj implements the interface specified by T. For example, obj is Object is always true.

• Using the Mirrors API (see this example):

  Expect.equals('T', someObject.simpleName)
  

Answer 2

Here is a simple explanation with a solution.

You have:

Object obj =t1;
where t1 is an object of class T.

And you have other object T called t.

T t = new T();

How to check if obj is the same type of t ?

Solution:

if(obj is t)
     print('obj is typeof t')
   else print('obj is not typeof t') 

Answer 3

Recently Object got the runtimeType getter. So now, we may not only compare type of object with another type, but actually get the class name of an object.

As in:

myObject.runtimeType.toString()

Furthermore, in the current version of Dart, you can skip the toString operation and directly compare runtimeType of object with target type:

myObject.runtimeType == int

or

myObject.runtimeType == Animal