TypeError worker takes 0 positional arguments but 1 was given

Question

I m trying to implement a subclass and it throws the error    TypeError  worker   takes 0 positional arguments but 1 was given  class KeyStatisticCollection DataDownloadUtilities DataDownloadCollection       def GenerateAddressStrings self           pass         def worker            pass     def DownloadProc self           pass

User · Answer

I get this error whenever I mistakenly create a Python class using def instead of class:

def Foo():
    def __init__(self, x):
        self.x = x
# python thinks we're calling a function Foo which takes 0 args   
a = Foo(x) 

TypeError: Foo() takes 0 positional arguments but 1 was given

Oops!

User · Answer

You forgot to add self as a parameter to the function worker   in the class KeyStatisticCollection

User · Answer

class KeyStatisticCollection DataDownloadUtilities DataDownloadCollection   def GenerateAddressStrings self       pass     def worker self       pass def DownloadProc self       pass

User · Answer

This can be confusing especially when you are not passing any argument to the method  So what gives   When you call a method on a class  such as work   in this case   Python automatically passes self as the first argument    Lets read that one more time  When you call a method on a class  such as work   in this case   Python automatically passes self as the first argument  So here Python is saying  hey I can see that work   takes 0 positional arguments  because you have nothing inside the parenthesis  but you know that the self argument is still being passed automatically  when the method is called  So you better fix this and put that self keyword back in   Adding self should resolve the problem  work self   class KeyStatisticCollection DataDownloadUtilities DataDownloadCollection   def GenerateAddressStrings self       pass     def worker self       pass def DownloadProc self       pass

User · Answer

If the method doesn t require self as an argument  you can use the  staticmethod decorator to avoid the error   class KeyStatisticCollection DataDownloadUtilities DataDownloadCollection        def GenerateAddressStrings self           pass           staticmethod     def worker            pass      def DownloadProc self           pass   See https   docs python org 3 library functions html staticmethod

User · Answer

Your worker method needs  self  as a parameter  since it is a class method and not a function  Adding that should make it work fine

User · Answer

When doing Flask Basic auth I got this error and then I realized I had wrapped view   kwargs  and it worked after changing it to wrapped view  args    kwargs

User · Answer

Check if from method with name method a   you call method with the same name method a with params  causing recursion

User · Answer

another use case for this error is when you import functions within the class definition   this makes the subsequent function calls a part of the class object   In this case you can use  staticmethod on the library import function or make a static path call directly to the function   see example below  In this example  self bar    will throw a TypeError  but it can be fixed in two ways    in lib py def bar      print  something to do      in foo py class foo      from  lib import bar    def   init   self       self bar     Option 1     in lib py def bar      print  something to do      in foo py class foo      from  lib import bar    def   init   self       lib bar     Option 2     in lib py   staticmethod def bar      print  something to do      in foo py class foo      from  lib import bar    def   init   self       self bar

[python] TypeError: worker() takes 0 positional arguments but 1 was given

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