I have a Python script and I am receiving the following error:
Traceback (most recent call last):
File "C:\Users\Tim\Desktop\pop-erp\test.py", line 1, in <module>
s = Something()
NameError: name 'Something' is not defined
Here is the code that causes the problem:
s = Something()
s.out()
class Something:
def out():
print("it works")
This is being run with Python 3.3.0 under Windows 7 x86-64.
Why can't the Something class be found?
Define the class before you use it:
class Something:
def out(self):
print("it works")
s = Something()
s.out()
You need to pass self as the first argument to all instance methods.
@staticmethod and @classmethod, just to keep things interesting :-P@classmethod in there -- but I was only trying to imply that you can change what the first argument is (or even if it gets passed at all). I realize there is nothing magical about the variable name self (apart from a very entrenched convention that really shouldn't be violated no matter what).
class Something:, and parses the class putting Something into the namespace.Note that sometimes you will want to use the class type name inside its own definition, for example when using Python Typing module, e.g.
class Tree:
def __init__(self, left: Tree, right: Tree):
self.left = left
self.right = right
This will also result in
NameError: name 'Tree' is not defined
That's because the class has not been defined yet at this point. The workaround is using so called Forward Reference, i.e. wrapping a class name in a string, i.e.
class Tree:
def __init__(self, left: 'Tree', right: 'Tree'):
self.left = left
self.right = right
from __future__ import annotations instead of wrapping the name in a string.You must define the class before creating an instance of the class. Move the invocation of Something to the end of the script.
You can try to put the cart before the horse and invoke procedures before they are defined, but it will be an ugly hack and you will have to roll your own as defined here:
I got the same error below:
NameError: name 'name' is not defined
When I don't define the getter method with @property while the setter and deleter are defined as shown below:
class Person:
def __init__(self, name):
self._name = name
# @property
# def name(self):
# return self._name
@name.setter
def name(self, name):
self._name = name
@name.deleter # Here
def name(self):
del self._name
