Python NameError name is not defined

Question

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  lt module gt      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

User · Accepted Answer

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

User · Answer

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

User · Answer

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   Make function definition in a python file order independent

[python] Python NameError: name is not defined

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