修改其類的數據對象的函數

Question

我想定義一個函數，將其稱爲test_controller()，並且我想將此函數傳遞給構造函數：my_thing = TestClass(test_controller)。該功能需要能夠修改其類的數據對象。我聽說過Python 3的nonlocal關鍵字，但我正在運行Python 2.7。可能嗎？我該怎麼做呢？這是我已經嘗試過的。

class TestClass(object): 

    def __init__(self, ctrl_func): 
     self.a = 4 
     self.ctrl_func = ctrl_func 

    def do_stuff(self): 
     self.ctrl_func() 

def test_controller(): 
    global a 
    a = 20 

my_thing = TestClass(test_controller) 
print my_thing.a   #this prints 4 
my_thing.ctrl_func() 
print my_thing.a   #this prints 4 but I want it to print 20 

Answer 1

您可以傳遞任何您想要修改的對象的引用。

class TestClass(object): 

    def __init__(self, ctrl_func): 
     self.a = 4 
     self.ctrl_func = ctrl_func 

    def do_stuff(self): 
     self.ctrl_func(self) 

def test_controller(self): 
    self.a = 20 

my_thing = TestClass(test_controller) 
print my_thing.a   #this prints 4 
my_thing.ctrl_func(my_thing) 
print my_thing.a   #this prints 4 but I want it to print 20 

或者，您可以ctrl_func轉換爲對象的綁定方法：

import types 

class TestClass(object): 

    def __init__(self, ctrl_func): 
     self.a = 4 
     self.ctrl_func = types.MethodType(ctrl_func, self) 

    def do_stuff(self): 
     self.ctrl_func() 

def test_controller(self): 
    self.a = 20 

my_thing = TestClass(test_controller) 
print my_thing.a   #this prints 4 
my_thing.ctrl_func() 
print my_thing.a   #this prints 4 but I want it to print 20 

參考：

• https://stackoverflow.com/a/1015405/8747
• http://igorsobreira.com/2011/02/06/adding-methods-dynamically-in-python.html