python __init__ 构造函数

class SQLHelper:

    def __init__(self):  # self = s1
        print("helo")

    def fetch(self, sql):
        pass

    def create(self, sql):
        pass

    def remove(self, nid):
        pass

    def modify(self, name):
        pass

# 实例化过程 会执行__init__ 的函数方法
s1 = SQLHelper()

‘‘‘
helo
‘‘‘

class SQLHelper:

    def __init__(self):  # self = s1
        print("helo")
        self.hhost = "c1.salt.com"
        self.uuserane = "alex"
        self.pwd = "123"

    def fetch(self, sql):
        pass

    def create(self, sql):
        pass

    def remove(self, nid):
        pass

    def modify(self, name):
        pass

# 实例化过程 会执行__init__ 的函数方法
s1 = SQLHelper()
print(s1.hhost, s1.uuserane, s1.pwd)

‘‘‘
helo
c1.salt.com alex 123
‘‘‘

class SQLHelper:

    def __init__(self, host, username, pwd):  # self = s1
        print("helo")
        self.hhost = host
        self.uuserane = username
        self.pwd = pwd

    def fetch(self, sql):
        print(sql)

    def create(self, sql):
        pass

    def remove(self, nid):
        pass

    def modify(self, name):
        pass

# 实例化过程 会执行__init__ 的函数方法
s1 = SQLHelper("c1.salt.com", "alex", "123")
s2 = SQLHelper("c2.salt.com", "mike", "123456")

s1.fetch("select * from A")


‘‘‘
helo
helo
select * from A
‘‘‘