结构化编程解决三角形问题

import math


class Triangle:
    REL_TOL = 1e-9

    def __new__(cls, *args, **kwargs):
        if cls.is_triangle(*args):
            instance = super().__new__(cls)
            return instance
        else:
            return None

    def __init__(self, a, b, c):
        self.a = a
        self.b = b
        self.c = c

    def get_perimeter(self):
        return self.a + self.b + self.c

    def get_area(self):
        p = self.get_perimeter() / 2
        area = (p * (p - self.a) * (p - self.b) * (p - self.c)) ** 0.5
        return area

    
    #@property装饰器会将方法转换为相同名称的只读属性
    @property
    def perimeter(self):
        return self.a + self.b + self.c

    @property
    def area(self):
        p = self.get_perimeter / 2
        area = (p * (p - self.a) * (p - self.b) * (p - self.c)) ** 0.5
        return area

    def is_right_angled(self):
        return (math.isclose(self.a ** 2 + self.b ** 2, self.c ** 2, rel_tol=Triangle.REL_TOL)
                or math.isclose(self.a ** 2 + self.c ** 2, self.b ** 2, rel_tol=Triangle.REL_TOL)
                or math.isclose(self.b ** 2 + self.c ** 2, self.a ** 2, rel_tol=Triangle.REL_TOL))

    def is_acute_angled(self):
        if not self.is_right_angled():
            if self.a ** 2 + self.b ** 2 > self.c ** 2 and self.a ** 2 + self.c ** 2 > self.b ** 2 and self.b ** 2 + self.c ** 2 > self.a ** 2:
                return True
        return False

    def is_obtuse_angled(self):
        if not self.is_right_angled():
            if self.a ** 2 + self.b ** 2 < self.c ** 2 or self.a ** 2 + self.c ** 2 < self.b ** 2 or self.b ** 2 + self.c ** 2 < self.a ** 2:
                return True
        return False

    def equal_to(self, other):
        #类型判断isinstance,此处判断other是否是Triangle的实例化对象
        if isinstance(other, Triangle):
            A = sorted((self.a, self.b, self.c))
            B = sorted((other.a, other.b, other.c))
            return A[0] == B[0] and A[1] == B[1] and A[2] == B[2]
        return -1

    def not_equal_to(self, other):
        if isinstance(other, Triangle):
            A = sorted((self.a, self.b, self.c))
            B = sorted((other.a, other.b, other.c))
            return A[0] != B[0] and A[1] != B[1] and A[2] != B[2]
        return -1

    def greater_than(self, other):
        if isinstance(other, Triangle):
            return self.get_area() > other.get_area()
        return -1

    def greater_equal(self, other):
        if isinstance(other, Triangle):
            return self.get_area() >= other.get_area()
        return -1

    def less_than(self, other):
        if isinstance(other, Triangle):
            return self.get_perimeter() < other.get_perimeter()
        return -1

    def less_equal(self, other):
        if isinstance(other, Triangle):
            return self.get_perimeter() <= other.get_perimeter()
        return -1
    
    
    
    #**************************************************************************************
    #                       魔术方法
    #**************************************************************************************
    #相等
    def __eq__(self, other):
        if isinstance(other, Triangle):
            A = sorted((self.a, self.b, self.c))
            B = sorted((other.a, other.b, other.c))
            return A[0] == B[0] and A[1] == B[1] and A[2] == B[2]
        return -1
    
    #不等
    def __ne__(self, other):
        if isinstance(other, Triangle):
            A = sorted((self.a, self.b, self.c))
            B = sorted((other.a, other.b, other.c))
            return A[0] != B[0] and A[1] != B[1] and A[2] != B[2]
        return -1
    
    #面积大于
    def __gt__(self, other):
        if isinstance(other, Triangle):
            return self.get_area() > other.get_area()
        return -1

    #面积大于等于
    def __ge__(self, other):
        if isinstance(other, Triangle):
            return self.get_area() >= other.get_area()
        return -1

    #周长小于
    def __lt__(self, other):
        if isinstance(other, Triangle):
            return self.get_perimeter() < other.get_perimeter()
        return -1

    #周长小于等于
    def __le__(self, other):
        if isinstance(other, Triangle):
            return self.get_perimeter() <= other.get_perimeter()
        return -1

    #类方法
    @classmethod
    def is_valid(cls, num):
        # print(cls.REL_TOL)
        return type(num) in {int, float} and num > 0
    
    #静态方法
    @staticmethod
    def is_triangle(a, b, c):
        # print(Triangle.REL_TOL)
        return Triangle.is_valid(a) and Triangle.is_valid(b) and Triangle.is_valid(c) and (a + b > c) and (
                b + c > a) and (a + c > b)


if __name__ == '__main__':
    print("Triangle类....")

Triangle类....

t = Triangle(3,4,5)

#周长
t.get_perimeter()

12

#面积
t.get_area()

6.0

#是否是直角三角行
t.is_right_angled()

True

#两个三角是否相等
s=Triangle(3,4,5)
t.equal_to(s)

True

#两个三角面积是否相等
t==s

True

#t三角面积是否大于s三角面积
#t>s
t.greater_than(s)

False

#t三角面积是否大于等于s三角面积
#t>=s
t.greater_equal(s)

True

#t三角周长是否小于等于s三角周长
#t<=s
t.less_equal(s)

True

isinstance() 函数

语法
isinstance(object, classinfo)

参数
object -- 实例对象。

classinfo -- 可以是直接或间接类名、基本类型或者由它们组成的元组。

返回值
如果对象的类型与参数二的类型（classinfo）相同则返回 True，否则返回 False。