在没有 arguments 的情况下调用超级初始化方法

Question

I have a questio about super().__init__() method. According to W3SCHOOLS the definition and usage (of super) is:

• The super() function is used to give access to methods and properties of a parent or sibling class.

• The super() function returns an object that represents the parent class.

However i really can't understand why and where can we use super().__init__() method without any argument in __init__ (since, even without super , the __init__ method of the parent class is called as soon as we insert the name of the parent's class on the parenthesis).

I AM NEW TO Objected Oriented programming so i am just trying to understand how it works!!!

To help you understand my problem see the example below:

class Rectangle:
    def __init__(self, length, width):
        self.length = length
        self.width = width

    def area1(self):
        return self.length * self.width

class Square(Rectangle):
    def __init__(self, length):
        super().__init__(length, length)

square = Square(4)
square.area()

Here we use it because we need to define the self.length, self.width on the Rectangle class
(we insert length, length).

However i don't know why we use it without any arguments like in the next example.
Since i know that we can access the methods and attributes of a parent class without the need to call the super.

class Example(QMainWindow):
    
    def __init__(self):
        super().__init__()
                
        self.lineEntry = QLineEdit(self)
        self.lineEntry.move(16,16)
        self.lineEntry.resize(200,40)
  
        self.setGeometry(50,50,320,200)
        self.setWindowTitle("QLineEdit Example")
        self.show()
        

        app = QApplication(sys.argv)
        ex = Example()
        sys.exit(app.exec_())

Answer 1

Not every attribute is passed to the constructor - some may be private attributes that have default values assigned in the constructor. Additionally, the parent class's constructor may do things other than just assigning attributes, such as setting up a cache. Without the super().__init__() , they won't run.