Question

Given below is a snippet from a class of which I am trying to create objects and getting error:

class FoF(object):
        def __init__(self,path):
                filepath=[]
                filepath.append(self.FileOrFolder(path))

Upon executing which I get the following error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "PathOps.py", line 6, in __init__
    def __init__(self,path):
  NameError: global name 'filepath' is not defined

After which I tried:

filepath=[]
class FoF(object):
        def __init__(self,path):
                global filepath.append(self.FileOrFolder(path))

And again:

File "<stdin>", line 1, in <module>
  File "PathOps.py", line 6, in __init__
    global filepath.append(self.FileOrFolder(path))
NameError: global name 'filepath' is not defined

What is causing the error and how do I fix it?

Answer 1

Try using insted of global the special word self.

So something like this

class FoF(object):
    def __init__(self,path):
        self.filepath=[]
        self.filepath.append(self.FileOrFolder(path))

The reason this error comes up is because what python thinks you’re trying to do is one of two things:

1. Either you’re trying to reference a global variable called filepath — which is clear that’s not what you’re trying
2. What’s not so clear is that you could also define a class attribute called filepath — the only problem with that is that you can’t define a class attribute with a function of that class. You can only do so within the class — outside a class function

So in order to declare variables within a function you have to use the word self before it.

Edit** if you want it to be an attribute of the class — as I’m assuming is what you meant you could do so like this:

class FoF(object):
    filepath=[]
    def __init__(self,path):
        self.filepath.append(self.FileOrFolder(path))