在不調用python中的構造函數的情況下使用類

Question

我有簡單的類來從數據庫中獲取查詢。

# myClass.py 
class DB: 
    def __init__ (self, host, user, password): 
     self.conn = MySQLdb.connect("localhost","****","****","***") 
     self.conn.set_character_set('utf8mb4') 
     cursor = self.conn.cursor() 
     cursor.execute('SET NAMES utf8mb4;') 
     cursor.execute('SET CHARACTER SET utf8mb4;') 
     cursor.execute('SET character_set_connection=utf8mb4;') 
    def query(self, q): 
      cursor = self.conn.cursor() 
      cursor.execute(q) 
      return cursor 

如果我使用下面的查詢與它工作正常，

from myClass import DB 
q = DB("..", "..", "..", "..") 
_fetch = q.query("... ") 

但是如果我想擺脫的第二行，因爲我聲明用戶，傳球，主機.. MyClass中的.py

所以，當我嘗試

from myClass import DB 
_fetch = DB.query("... ") 

它不會允許我連接，即使我刪除self,關鍵字查詢

Answer 1

你可以嘗試這樣的：

# myClass.py 

# code will be executed only once a the first import 
conn = MySQLdb.connect("localhost","****","****","***") 
conn.set_character_set('utf8mb4') 
cursor = conn.cursor()  
cursor.execute('SET NAMES utf8mb4;') 
cursor.execute('SET CHARACTER SET utf8mb4;') 
cursor.execute('SET character_set_connection=utf8mb4;') 

class DB: 
    # class attribute shared among all DB instance 
    cursor = conn.cursor() 
    # class method 
    @classmethod 
    def query(cls, q): 
     cls.cursor.execute(q) 
     return cursor 

Answer 2

您可以創建類對象的人，然後就導入和使用它：在其他模塊

# myClass.py 
class DB: 
    def __init__ (self, host, user, password): 
     # ... 

db = DB("..", "..", "..", "..") # Create object ones. 

某處：

from myClass import db 

db.query("... ")