python魔法函数之__getitem__

魔法函数会增强python类的类型，独立存在

class Company:
    def __init__(self, employees):
        self.employees = employees

    def __getitem__(self, item):
        return self.employees[item]


company = Company(['a', 'b', 'c'])
for val in company:
    print(val)
company1 = company[:2]
for val in company1:
    print(val)

结果：
a
b
c
a
b
for循环迭代时，如果对象不具有iterator接口，就会调用类的__getitem__魔法函数（前提是定义了），上述的__getitem__把类变成了序列，所以可切片可遍历