python - 修改其类的数据对象的函数

Question

我想定义一个函数，将其命名为 test_controller()，并且我想将此函数传递给构造函数:my_thing = TestClass(test_controller)。该函数需要能够修改其类的数据对象。我听说过 Python 3 的 nonlocal 关键字，但我运行的是 Python 2.7。是否可以？我该怎么做呢？这是我已经尝试过的。

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

您可以传入对您想要修改的任何对象的引用。

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，您可以将 ctrl_func 转换为对象的绑定(bind)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

引用:

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