将cls参数传递给@classmethod来解决这个问题。

@classmethod
def test(cls):
    return ''

简单地说

在Python中，你应该将self作为类中所有定义方法的第一个参数:

class MyClass:
  def method(self, arg):
    print(arg)

然后你可以根据你的直觉使用你的方法:

>>> my_object = MyClass()
>>> my_object.method("foo")
foo

为了更好地理解，你也可以阅读这个问题的答案:自我的目的是什么?

正如在其他回答中提到的那样——当您使用实例方法时，需要将self作为第一个参数传递——这是错误的来源。

除此之外，重要的是要理解只有实例方法才将self作为第一个参数来引用实例。

如果方法是Static，则不传递self，而是传递cls参数(或class_)。

请参阅下面的示例。

class City:

   country = "USA" # This is a class level attribute which will be shared across all instances  (and not created PER instance)

   def __init__(self, name, location, population):
       self.name       = name
       self.location   = location
       self.population = population
 
   # This is an instance method which takes self as the first argument to refer to the instance 
   def print_population(self, some_nice_sentence_prefix):
       print(some_nice_sentence_prefix +" In " +self.name + " lives " +self.population + " people!")

   # This is a static (class) method which is marked with the @classmethod attribute
   # All class methods must take a class argument as first param. The convention is to name is "cls" but class_ is also ok
   @classmethod
   def change_country(cls, new_country):
       cls.country = new_country

一些测试只是为了让事情更清楚:

# Populate objects
city1 = City("New York",    "East", "18,804,000")
city2 = City("Los Angeles", "West", "10,118,800")

#1) Use the instance method: No need to pass "self" - it is passed as the city1 instance
city1.print_population("Did You Know?") # Prints: Did You Know? In New York lives 18,804,000 people!

#2.A) Use the static method in the object
city2.change_country("Canada")

#2.B) Will be reflected in all objects
print("city1.country=",city1.country) # Prints Canada
print("city2.country=",city2.country) # Prints Canada

当你没有指定__init__()或任何其他方法寻找的参数的no时，就会发生这种情况。

例如:

class Dog:
    def __init__(self):
        print("IN INIT METHOD")

    def __unicode__(self,):
        print("IN UNICODE METHOD")

    def __str__(self):
        print("IN STR METHOD")

obj = Dog("JIMMY", 1, 2, 3, "WOOF")

当你运行上面的程序时，它会给你一个这样的错误:

TypeError: __init__()接受1个位置参数，但给出了6个

我们怎么才能摆脱这东西?

只需传递参数，即__init__()方法要查找的内容

class Dog:
    def __init__(self, dogname, dob_d, dob_m, dob_y, dogSpeakText):
        self.name_of_dog = dogname
        self.date_of_birth = dob_d
        self.month_of_birth = dob_m
        self.year_of_birth = dob_y
        self.sound_it_make = dogSpeakText

    def __unicode__(self, ):
        print("IN UNICODE METHOD")

    def __str__(self):
        print("IN STR METHOD")


obj = Dog("JIMMY", 1, 2, 3, "WOOF")
print(id(obj))

当我睡眠不足时，我会得到这个错误，并使用def而不是class创建一个类:

def MyClass():
    def __init__(self, x):
        self.x = x

a = MyClass(3)
-> TypeError: MyClass() takes 0 positional arguments but 1 was given

刚接触Python时，我以错误的方式使用Python的**特性时遇到了这个问题。试着从某处调用这个定义:

def create_properties_frame(self, parent, **kwargs):

使用没有双星的调用会导致问题:

self.create_properties_frame(frame, kw_gsp)

TypeError: create_properties_frame()接受2个位置参数，但给出了3个

解决方案是在参数中添加**:

self.create_properties_frame(frame, **kw_gsp)