Are we passing any parameter to the init method

Question

class Vector2D:
def __init__(self, x, y):
self.x = x
self.y = y
def __add__(self, other):
return Vector2D(self.x + other.x, self.y + other.y)

first = Vector2D(5, 7)
second = Vector2D(3, 9)
result = first + second
print(result.x)
print(result.y)

Answer 1

self is a reference to the current instance of the class... When you call init though you do not pass it any argument for self.

Example: init(2, 3) and not init(self, 2, 3)

Answer 2

In this case, yes we are passing three parameters to the __init__ method self, x value and y value.

Answer 3

i believe self passes the instance of the class but I am not sure.

Answer 4

what is the value of self?

does it always stores the object which is calling it

Answer 5

then what are we passing in

Answer 6

then what are we passing in the add method

Answer 7

In the add method, we are passing second.

result = first + second

The add method is called when the + sign is encountered and whatever is listed after the + sign is the argument that is passed as other. So in this case, other is Vector2D(3, 9) because of this line of code: second = Vector2D(3, 9)

I copied the code from above to help us follow it. I added comments to help.

class Vector2D:
def __init__(self, x, y):
self.x = x
self.y = y
def __add__(self, other):
return Vector2D(self.x + other.x, self.y + other.y)

first = Vector2D(5, 7) # first is assigned the value of (5, 7)
second = Vector2D(3, 9) # second is assigned the value of (3, 9)
result = first + second # second is the argument sent to __add__
print(result.x) # result.x is the sum of both x values, 5 added to 3 = 8
print(result.y) # result.y is the sum of both y values, 7 added to 9 = 16

I hope this helps. :-)