LU04.L03 - Rechtecke

rectangle.py

"""Reference solution: Rectangle - Constructor and Equality.
 
Contains two implementations of the same concept:
- Rectangle:    "normal" class with manual constructor and __eq__
- RectangleDC:  dataclass with automatically generated constructor and __eq__
"""
 
class Rectangle:
    """Rectangle with width and height (classic implementation)."""
 
    def __init__(self, width: float = 1.0, height: float = 1.0) -> None:
        if width <= 0 or height <= 0:
            raise ValueError("width and height must be greater than 0")
        self.width = width
        self.height = height
 
    def __eq__(self, other: object) -> bool:
        if not isinstance(other, Rectangle):
            return NotImplemented
        return self.width == other.width and self.height == other.height
 
    def __repr__(self) -> str:
        return f"Rectangle(width={self.width}, height={self.height})"
 
    @property
    def width(self):
        """ returns the width """
        return self._width
 
    @width.setter
    def width(self, value):
        """ sets the width """
        self._width = value
 
    @property
    def heigth(self):
        """ returns the heigth """
        return self._heigth
 
    @heigth.setter
    def heigth(self, value):
        """ sets the heigth """
        self._heigth = value

rectangle_dc.py

from dataclasses import dataclass, field
 
 
@dataclass
class RectangleDC:
    """Rectangle with width and height (dataclass implementation).
 
    @dataclass automatically generates the constructor and __eq__ based on
    the declared attributes. A custom __eq__ method is therefore not
    needed - the generated comparison checks class and all attributes.
    """
 
    _width: float = field(default=1.0)
    _height: float = field(default=1.0)
 
    def __post_init__(self) -> None:
        print (f"RectangleDC created with width={self.width} and height={self.height}")
        if self.width <= 0 or self.height <= 0:
            raise ValueError("width and height must be greater than 0")
 
    @property
    def width(self):
        """ returns the width """
        return self._width
 
    @width.setter
    def width(self, value):
        """ sets the width """
        self._width = value
 
    @property
    def height(self):
        """ returns the height """
        return self._height
 
    @height.setter
    def height(self, value):
        """ sets the height """
        self._height = value

René Probst, bearbeitet durch Marcel Suter