Variable referenced before assignment in Python function

Question

Can someone please tell me what's wrong with the following Python code.

def education():
 class College:
 
 type = "University"
 def __init__(self, name, location):
 self.name = name
 self.location = location
 iet = College("IET", "Kanpur")
 jim = College("JIM", "Lucknow")
 edu1 = print("IET is a {}".format(iet.__class__.type))
 edu2 = print("JIM is also a {}".format(jim.__class__.type))
 loc1 = print("{} is located in {}".format(iet.name, iet.location))
 loc2 = print("{} is located in {}".format(jim.name, jim.location))
 
 return edu1, edu2, loc1, loc2
education()
NameError: free variable 'College' referenced before assignment in enclosing scope

I get the above NameError while calling the function.

Thanks in advance.

Answer 1

You are trying to create College() objects inside the class College, but outside any function in that class. That is what's causing the error.

If you unindent the part after __init__, it will work, like so:

def education():
 class College:
 type = "University"
 def __init__(self, name, location):
 self.name = name
 self.location = location
 iet = College("IET", "Kanpur")
 jim = College("JIM", "Lucknow")
 edu1 = print("IET is a {}".format(iet.__class__.type))
 edu2 = print("JIM is also a {}".format(jim.__class__.type))
 loc1 = print("{} is located in {}".format(iet.name, iet.location))
 loc2 = print("{} is located in {}".format(jim.name, jim.location))
 return edu1, edu2, loc1, loc2
education()

However, I would advise to define the class College before the function, like so:

class College:
 type = "University"
 def __init__(self, name, location):
 self.name = name
 self.location = location
 
 
def education():
 iet = College("IET", "Kanpur")
 jim = College("JIM", "Lucknow")
 edu1 = print("IET is a {}".format(iet.__class__.type))
 edu2 = print("JIM is also a {}".format(jim.__class__.type))
 loc1 = print("{} is located in {}".format(iet.name, iet.location))
 loc2 = print("{} is located in {}".format(jim.name, jim.location))
 return edu1, edu2, loc1, loc2
education()

Edit: You're declaring type in class College, thereby hiding Python's type. It is not advised to use names for variables that are default keywords in Python, such as list, dict, type.

Edit2: As Ishwar pointed out, you're storing the return from print statements in loc1 and loc2. print() always returns None, so there is no use in storing it in variables. If you wanted to store the formatted strings, store those in variables and then print those variables.

• Ishwar: Also the print object is stored in returned variables instead of the actual value. This is useless as print returns None. Instead string must be stored in edu1, edu2, loc1 and loc2.

Answer 2

Python uses indentation to determine if code is part of the function or part of the class. Here your code referencing College is indented such that it forms part of the class and not your function.

Additionally, you are defining you class inside your function. I can see no good reason why you should do this. Also your variable type is a reserved keyword, so its advised to change this to something else, such as college_type. Lastly the print statement returns None, so none of your variables will be populated with any data.

See the code below:

class College:
 
 college_type = "University"
 def __init__(self, name, location):
 self.name = name
 self.location = location
def education():
 iet = College("IET", "Kanpur")
 jim = College("JIM", "Lucknow")
 
 edu1 = iet.__class__.college_type
 edu2 = jim.__class__.college_type
 print("IET is a {}".format(edu1))
 print("JIM is also a {}".format(edu2))
 loc1 = iet.location
 loc2 = jim.location
 print("{} is located in {}".format(iet.name, loc1))
 print("{} is located in {}".format(jim.name, loc2))
 
 return edu1, edu2, loc1, loc2
education()

• Franco Morero: don´t use type = bla, `type´ is a reserver word in python
• Jurgen Strydom: Good catch @FrancoMorero
• R. dV: Also the print object is stored in returned variables instead of the actual value. This is useless as print returns None.
• Jurgen Strydom: Very true @R. dV