Python創(chuàng)建類的時(shí)候，加()和不加有什么區(qū)別、聯(lián)系？

在Python中定義類class的時(shí)候，可以加上():

class Employee():
    """這里是Employee的__doc__"""
    empCount = 0
    __name1 = 'safety'
    def __init__(self,name,salary):
        self.name = name
        self.salary = salary
        Employee.empCount += 1
    
    def display_count(self):
        print('Totall employee count:{}'.format(Employee.empCount))
    
    def display_employee(self):
        print('Name:{},  Salary:{}'.format(self.name, self.salary))

也可以不加上():

class Employee:
    """這里是Employee的__doc__"""
    empCount = 0
    __name1 = 'safety'
    def __init__(self,name,salary):
        self.name = name
        self.salary = salary
        Employee.empCount += 1
    
    def display_count(self):
        print('Totall employee count:{}'.format(Employee.empCount))
    
    def display_employee(self):
        print('Name:{},  Salary:{}'.format(self.name, self.salary))

目前我觀察的結(jié)果是：二者沒(méi)有區(qū)別；實(shí)際上它們有無(wú)區(qū)別呢？如果真的沒(méi)有區(qū)別，那么哪種寫(xiě)法是正確的？我在《Python基礎(chǔ)教程》中看到的是不加括號(hào)。