91 lines
3.3 KiB
Python
91 lines
3.3 KiB
Python
"""
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Now that we know the basics of classes, variables, and functions, we will move on to more
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abstract ideas.
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I'm also going to introduce type hinting; this reduces ambiguity and improves readability.
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Key Concepts:
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**Encapsulation** is the concept of grouping related data and methods within a
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class and restricting access to them to control how they are used.
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**Access Modifiers** are used to determine who/what can access a certain attribute or method.
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- **Public**: Accessible from any part of the code. Used for attributes and methods intended to be part
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of the class's interface for external use.
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- **Protected**: Intended for internal use within the class and its subclasses. "_value" represents it.
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Useful for attributes/methods that should be accessible in subclasses but not publicly.
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- **Private**: Only accessible within the class, represented by "__value". Useful for securing sensitive
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data or internal methods that should not be altered externally.
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IMPORTANT: Python does not strictly enforce access control, so these conventions mainly serve as guidelines.
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"""
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# This is the abstraction library in Python
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from abc import ABC, abstractmethod
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# Type hinting, not needed but reduces ambiguity. Note: not enforced at runtime.
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from typing import Optional
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# An abstract class, provides a blueprint for other classes to inherit.
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class Shape(ABC):
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# This method is required in all subclasses, ensuring they provide their own area calculation.
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@abstractmethod
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def area(self) -> float:
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"""Implemented to ensure each subclass contains this method."""
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class Rectangle(Shape):
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def __init__(self, width: float, height: float):
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# A private attribute to store width.
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self.__width = width
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# A private attribute to store height.
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self.__height = height
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# This allows access to the private 'width' attribute in a controlled way.
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@property
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def width(self) -> float:
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return self.__width
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# This allows you to set the value of 'width' after initialization.
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@width.setter
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def width(self, value: float):
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if value <= 0:
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raise ValueError("Width must be positive.")
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self.__width = value
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# This allows access to the private 'height' attribute in a controlled way.
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@property
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def height(self) -> float:
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return self.__height
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# This allows you to set the value of 'height' after initialization.
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@height.setter
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def height(self, value: float):
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if value <= 0:
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raise ValueError("Height must be positive.")
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self.__height = value
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def area(self) -> float:
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# Calculates the area of the rectangle.
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return self.__width * self.__height
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def set_dimensions(self, width: Optional[float] = None, height: Optional[float] = None):
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if width is not None:
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# Sets 'width' using the setter.
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self.width = width
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if height is not None:
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# Sets 'height' using the setter.
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self.height = height
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rect = Rectangle(5, 10)
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# Prints the area of the rectangle (5 * 10 = 50).
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print(rect.area())
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# Updates 'width' using the setter, height remains the same.
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rect.set_dimensions(width=8)
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# Prints the new area of the rectangle (8 * 10 = 80).
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print(rect.area())
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