Constructors

Constructor Overloading

class Point:
    x: float
    y: float

    def __init__(self):
        self.x = 0.0
        self.y = 0.0

    def __init__(self, x: float, y: float):
        self.x = x
        self.y = y

    def __init__(self, other: Point):
        self.x = other.x
        self.y = other.y

Constructor Chaining

One constructor can delegate to another using self.__init__(...) as the first statement. This maps to C#'s : this(...) syntax:

class Point:
    x: float
    y: float

    def __init__(self):
        self.__init__(0.0, 0.0)  # Chains to the two-parameter constructor

    def __init__(self, x: float, y: float):
        self.x = x
        self.y = y

    def __init__(self, xy: float):
        self.__init__(xy, xy)    # Chains to the two-parameter constructor

Rules for Constructor Chaining:

• self.__init__(...) must be the first statement in the constructor body
• Only one self.__init__() call is allowed per constructor
• The compiler detects this pattern and transforms it to C#'s : this(...) syntax
• After the chained constructor returns, execution continues with the rest of the body (if any)

class Rectangle:
    x: float
    y: float
    width: float
    height: float

    def __init__(self, width: float, height: float):
        self.__init__(0.0, 0.0, width, height)  # Chain first
        print("Created rectangle")              # Then other statements

    def __init__(self, x: float, y: float, width: float, height: float):
        self.x = x
        self.y = y
        self.width = width
        self.height = height

Implementation - ✅ Native - __init__() maps directly to C# constructor methods. - 🔄 Lowered - self.__init__(...) as first statement transforms to : this(...) in C#.