每次我们对类进行变量更改时，我希望能够更改类中的变量(在本例中为 greet)。
截图是这个:
class Greet(object):
def __init__(self, name="", age="", job=""):
self.name = name
self.age = age
self.job = job
self.greet = "Hello"
if self.name:
self.greet = self.greet + " " + self.name
if self.age:
self.greet = self.greet + ". Good to know that you is " + self.age + " years old"
if self.job:
self.greet = self.greet + ". I think being a " + self.job + " is amazing."
def shout(self):
print self.greet
return True
g1 = Greet(name="John Doe", job="Programmer")
g2 = Greet(name="Janis Duh", age="34", job="Singer")
g2.name = "Janis Joplin"
g3 = Greet()
g3.name = "Smith"
g3.age = "22"
g3.job = "Designer"
print ("Name %s\nAge %s\nJob %s\nGreet %s\n" % ( g1.name, g1.age, g1.job, g1.greet))
g1.shout
print ("Name %s\nAge %s\nJob %s\nGreet %s\n" % ( g2.name, g2.age, g2.job, g2.greet))
g2.shout
print ("Name %s\nAge %s\nJob %s\nGreet %s\n" % ( g3.name, g3.age, g3.job, g3.greet))
g3.shout
输出是:
Name John Doe
Age
Job Programmer
Greet Hello John Doe. I think being a Programmer is amazing.Name Janis Joplin
Age 34
Job Singer
Greet Hello Janis Duh. Good to know that you is 34 years old. I think being a Singer is amazing.Name Smith
Age 22 Job Designer
Greet Hello
shout 方法在任何情况下都不会正确打印“问候语”。即使在正确设置 self.greet 的情况下。
g1 对象打印正常，因为我在创建实例时声明了变量。
g2 正确更改了变量名，但问候语仍然指向旧值，似乎没有更新。
g3 更糟糕的是，可能出于同样的原因，g2 没有在问候时正确更新名称。
欢迎指点
(后期编辑)
按照 Adam Smith 的说法，我宁愿尝试将“greeting”保留为实例属性，如下所示:
def greet(self):
self.greeting = "Hello!"
if self.name:
self.greeting += " {0.name}."
if self.age:
self.greeting += " Good to know you are {0.age} years old."
if self.job:
self.greeting += " I think being a {0.job} is amazing."
print(self.greeting.format(self))
...
g = Greeter(...)
g.greet()
有效，但是
print g.greeting
给我这样的东西:
Hello! {0.name}. Good ...
请您参考如下方法:
听起来您需要在函数中生成它，因此每次调用它时都会计算它。
class Greeter(object):
def init(self, ...):
...
def greet(self):
greeting = "Hello!"
if self.name:
greeting += " {0.name}."
if self.age:
greeting += " Good to know you are {0.age} years old."
if self.job:
greeting += " I think being a {0.job} is amazing."
print(greeting.format(self))
