Python-有没有一种方法可以获取对象的所有属性

Question

So I have a class called 'Car' in another .py file (MyClasses.py)

class Car:
    tires = 4
    color = ""
    speed = 0
    engine = ""

and in my main

import MyClasses

ferrari = MyClasses.Car()
ferrari.color = "Red"
ferrari.engine = "Fast"
ferrari.speed = 200

for prpty in ferrari:
    print(prpty)

the output I want is like this:

tires = 4
color = Red
speed = 200
engine = Fast

I know the format of the output depends on me. Only if in my for-loop I can get the property name and its value base on my object.

Answer 1

dir() gives all attributes, in order to get class variables we filter it as shown below:

>>> dir(ferrari)
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'color', 'engine', 'speed', 'tires']

>>> classVariables = [attr for attr in dir(ferrari) if not callable(getattr(ferrari, attr)) and not attr.startswith("__")]

>>> print(classVariables)
['color', 'engine', 'speed', 'tires']

Answer 2

Why not make a function to print all the attributes of your class ... This would save you all the hassle... Like:

class Car:
       tires=4
       speed=0
       color=" "
       def print_atr(self):
               print("tires = ",self.tires)
               print("speed = ",self.speed)
               print("color = ",self.color)

Answer 3

Here is a solution:

ferrari = Car()
errari.color = "Red"
ferrari.engine = "Fast"
ferrari.speed = 200
for attr in [i in dir(ferrari) if not i.startswith('_')]:
    print('{}: {}'.format(attr, getattr(ferrari, attr))

Answer 4

Better to define the __str__ at the time of creation of the class. If class is yours and you create the class then whey not include all the attribute there. If you just want to get the list all the attributes of a class then dir will be good. But for your intended output

class Car:
    tires = 4
    color = ""
    speed = 0
    engine = ""

    def __str__(self):
        return "tires="+str(self.tires)+"\ncolor="+self.color+"\nengine="+self.engine
        ##Include all the attribute here as above in intended way.


ferrari = Car()
ferrari.color = "Red"
ferrari.engine = "Fast"
ferrari.speed = 200

honda = Car()
honda.color = "Black"
honda.engine = "Slow"
honda.speed = 100

print ferrari
print honda

Like in JAVA we have toString() method that we can override to change the default behavior of printing an object, similarly we do have in Python too that we can define behavior of printing an object.

Your intended out put is

tires = 4
color = Red
speed = 200
engine = Fast

so update def __str__(self): method (little bit of update) and will work for everytime you print any object of the Car class

Answer 5

the simplest solution is using vars() for example:

print vars(ferrari)

will print

{'engine': 'Fast', '__module__': '__main__', 'color': 'Red', 'tires': 4, 'speed': 200, '__doc__': None}

to get what you want here is the code

fe = vars(ferrari)
for item in [i for i in fe if not i.startswith("_")]:
    print('{}: {}'.format(item, getattr(ferrari, item)))

this will print

engine: Fast
color: Red
tires: 4
speed: 200