Question

In the python example below, methods and attributes seem to be out of scope but they still work, what is happening?

for module in output:
    a = 1
    attributes=[]
    methods=[]
    for branch in module[2]:

        for leaf in branch[2]:
            if leaf[0]=="method":
                methods.append(leaf[1]) 
            if leaf[0]=="attribute":
                attributes.append(leaf[1])
print methods
print attributes
print module[0]
print a

but if I outdent one more level it stops working

for filename in os.listdir("."):
    print filename
    fName, fExtension = os.path.splitext(filename)
    print fName, fExtension
    if fExtension == ".idl":
        f = open(filename)
        idl = f.read()
        f.close()
        output = parse(idl)
        pprint.pprint(output)
        root={}
        for module in output:
            a = 1
            attributes=[]
            methods=[]
            for branch in module[2]:
                for leaf in branch[2]:
                    if leaf[0]=="method":
                        methods.append(leaf[1]) 
                    if leaf[0]=="attribute":
                        attributes.append(leaf[1])
    print methods
    print module[0]

it says: NameError: name ‘methods’ is not defined
I’m using python 2.7

Answer 1

As indicated in the comments, for loops, while loops, if statements, etc. do not create a new scope. In fact, the only things that create a new scopes are functions, classes, modules and methods. Therefore, when you create a new variable inside a for loop, it is available outside of that loop because they share the same scope.