Python可变属性数

Question

I'm new to ptyhon I'm trying to do something that should be quite simple but I can't do it.

I have to create objects that will have a different number of attributes each time. For example :

OBJECT A
    Attribute 1
    Attribute 2
    Attribute 3
OBJECT B
    Attribute 1
    Attribute 2

The attribute 1 will always be there (with different values but there will be at least one attribute in the object). I've created an example class :

class car():
    def__init__(self, Color, **kwargs):
        self.Color = Color 

        for key, value in kwargs.iteritems():
            setattr(self, key, value)

So now I have to call the contructor, but as the number of attributes will be variable, how should I do it ?

CAR1_ATTRIBUTES = (Passengers = 5, Tires = 4)
CAR2_ATTRIBUTES = (DriverName = "John", Tires = 4, DoorsNumber = 5)
CAR3_ATTRIBUTES = (DriverName = "Tom", Velocimeter = "Y", DoorsNumber = 4)

CarsList = []
for i in range(0,3):
    CarObject = Car("RED", RESTOFATTRIBUTES)
    CarsList.append(CarObject)

"RESTOFATTRBUTES" will be variable (it could be one single argument or 1563...)

Answer 1

You can pass any number of named parameters key = value , for example,

Car("RED", Passengers = 5, Tires = 4)

and they will be seen as the key : value pairs of the dictionary kwargs. Or directly pass the dictionary:

RESTOFATTRIBUTES = {"Passengers": 5, "Tires": 4}
Car("RED", **RESTOFATTRIBUTES)

You don't have to use the ** syntax. You could also have used the * syntax. You define the function def Car(color, *args): . In the body of the funcion, args is then a tuple where the first element corresponds to, say, Passengers, the second corresponds to, say, Tire, etc. You call Car this way:

Car("RED", 5, 4)

or

RESTOFATTRIBUTES = (5, 4)
Car("RED", *RESTOFATTRIBUTES)

There can be more than only two extra attributes, if the body of the function CAR manages it.

This was a duplicate in a way, but there was nothing wrong in providing an answer in the specific context of this question.