This code
def reportRealDiagnostics():
ranks = 0
class Rank:
def __init__(self):
global ranks
ranks += 1
rank = Rank()
reportRealDiagnostics()
produces
NameError: global name 'ranks' is not defined
I am sure that this is all what you need to answer the question.
When you use global ranks it looks for ranks in the global scope not in enclosing scope, so you get that error. The ranks you've defined is part of the enclosing scope.
In Python3 this has been resolved and you can modify ranks by using the nonlocal keyword:
def reportRealDiagnostics():
ranks = 0
class Rank:
def __init__(self):
nonlocal ranks
ranks += 1
rank = Rank()
reportRealDiagnostics()
In Python2 you can define it as a function attribute:
def reportRealDiagnostics():
class Rank:
def __init__(self):
reportRealDiagnostics.ranks += 1
rank = Rank()
reportRealDiagnostics.ranks = 0
reportRealDiagnostics()
There are some other alternatives too: nonlocal keyword in Python 2.x
ranks in the global scope, it is just hidden in the function's namespace. Multiple invocations of reportRealDiagnostics will use the same variable. It still might be OK.
ranks variable to a proper value in the parent function. Caller should not do that. He better not beware that such variable even exists. I have checked that you can declare the variable easily by simply defined in global reportRealDiagnostics function. You should have def f(): global r; r = 1; class C: __init__ global r; access(r)You should use variable as nonlocal:
nonlocal ranks
?).