Missing 1 required positional argument and no value for argument 'self' in unbound method errors in class based python program

Question

Why am I getting these errors: Console: "TypeError: printTodos() missing 1 required positional argument: 'self'"

Squiggly underline in VS code under "TodoList" on the last 2 lines with the error "No value for argument 'self' in unbound method callpylint(no-value-for-parameter)"

class TodoList:
    def __init__(self, todos):
        self.todos = todos
        self.count = 1
        self.indent_width = "  "

    def add_todo(self):
        response = input("Please input a todo: \n")
        self.todos.append(self.indent_width + response)

    def printTodos(self):
        for todo in self.todos:
            print(self.indent_width + str(self.count) + "." + todo)
            self.count += 1

todo_list = TodoList(["Have fun", "Chill"])

while (True):
    TodoList.add_todo()
    TodoList.printTodos()

Thanks for any advice!

Because you are trying to call it on the class, not on an instance. When accessed on the class, it is just a regular function, in which case, it requires the argument you specified. — juanpa.arrivillaga, Dec 31 '20 at 03:57
Might also be good to read the Python docs on [Classes and Method Objects](https://docs.python.org/3/tutorial/classes.html#class-objects). — Gino Mempin, Dec 31 '20 at 04:03

score 1 · Answer 1 · answered Dec 31 '20 at 03:56

1

Change from this

while (True):
    TodoList.add_todo()
    TodoList.printTodos()

To this

while (True):
    todo_list.add_todo()
    todo_list.printTodos()

answered Dec 31 '20 at 03:56

Ryujinzz

74
3

score -3 · Answer 2 · answered Dec 31 '20 at 03:58

You need to have indent_width in your init argument

class TodoList:
    def __init__(self, todos, indent_width):
        self.todos = todos
        self.count = 1
        self.indent_width = "  "

    def add_todo(self):
        response = input("Please input a todo: \n")
        self.todos.append(self.indent_width + response)

    def printTodos(self):
        for todo in self.todos:
            print(self.indent_width + str(self.count) + "." + todo)
            self.count += 1

todo_list = TodoList(["Have fun", "Chill"])

while (True):
    TodoList.add_todo()
    TodoList.printTodos()

Missing 1 required positional argument and no value for argument 'self' in unbound method errors in class based python program

2 Answers2