Question

我希望变量不仅仅是在我设置它时设置。和界面尽可能干净。

简短：我想要的是什么：

# have class with a variable that I can access:
print myInstance.var
42
# change the variable
myInstance.var = 23
# have the change kick off another method:
self.var was changed: 23!!

嗯..所以我可以做的：使用变量和setter方法：

class Test:
    def __init__(self):
        self.var = 1
        print( 'self.var is: ' + str(self.var) )
    def setVar(self, value):
        self.var = value
        print( 'self.var changed: ' + str(self.var) )

t = Test()
self.var is: 1

# so I have t.var at hand:
print t.var
1

# and change it this way
t.setVar(5)
self.var changed: 5

但是后来我有2个不同的东西可供使用.. 好的，我可以创建一个与var：

交互的方法

class Test:
    def __init__(self):
        self.var = 1
        print( 'self.var is: ' + str(self.var) )
    def method(self, value=None):
        if value == None:
            return self.var
        self.var = value
        print( 'self.var changed: ' + str(self.var) )

t = Test()
self.var is: 1
# to get the value then:
print t.method()
1
# to set it:
t.method(4)
self.var changed: 4
# and verifiy:
print t.method()
4

这已经很好了。我在其他语言的不同帖子中看过它。但我不知道。在python中有更好的解决方案吗？！？

也许我是偏执狂但是对我而言，只是做t.var = 5并且也有一些事情开始变得更好。

Answer 1

我认为你想要python属性。检查this out。类似的东西：

class Test:
    def __init__(self):
        self._var = 1

    @property
    def var(self):
        return self._var

    @var.setter
    def var(self, value):
        # add stuff here that you want to happen on var assignment
        self._var = value

Answer 2

您可以使用property。请注意，如果setter方法很昂贵，最好使用方法。人们期望属性访问速度很快。

class Foo(object):
    def __init__(self):
        self._var = None
    @property
    def var(self):
        return self._var
    @var.setter
    def var(self, whatever):
        self._var = whatever
        do_whatever()

x = Foo()
print x.var # prints None
x.var = 2   # sets x.var and does whatever

如何在python类中创建更好的变量接口

2 个答案: