Difference between type() and isinstance()
Let's understand the difference between type() and isinstance() with the example code below.
class Polygon:
def sides_no(self):
pass
class Triangle(Polygon):
def area(self):
pass
obj_polygon = Polygon()
obj_triangle = Triangle()
print(type(obj_triangle) == Triangle) # true
print(type(obj_triangle) == Polygon) # false
print(isinstance(obj_polygon, Polygon)) # true
print(isinstance(obj_triangle, Polygon)) # true
Output
True False True True
In the above example, we see that type() cannot distinguish whether an instance of a class is somehow related to the base class. In our case, although obj_triangle is an instance of child class Triangle, it is inherited from the base class Polygon. If you want to relate the object of a child class with the base class, you can achieve this with isinstance().