I am new to object-oriented programming and I have some trouble with declaring global variables that are set to a method inside a class. I declared them in the __init__ method (I want them to be inside the class, not outside) with self.censored_transcript = self.apply_filter(), and within this file, everything works fine. But when I import the class in a different .py file and instantiate the Profanity class, the following error occurs: UnboundLocalError: local variable 'censored_transcript' referenced before assignment. I have done quite some research on this topic but can't find anything that fits my case. The global statement does not work. Can anyone please let me know how I can fix this? Thank you very much in advance!
File 1 (file to be imported), called profanity_filter.py:
from better_profanity import profanity
class Profanity(object):
def __init__(self, transcript_filename, wordlist_filename):
self.__transcript_filename = transcript_filename
self.__wordlist_filename = wordlist_filename
self.__transcript = self.__load_transcript()
self.censored_transcript = self.apply_filter()
def __load_transcript(self):
f = open(self.__transcript_filename, "r")
file = f.read()
f.close()
return file
def apply_filter(self):
if __name__ == "__main__":
profanity.load_censor_words_from_file(self.__wordlist_filename)
censored_transcript = profanity.censor(self.__transcript)
return censored_transcript
File 2 (test file):
from profanity_filter import Profanity
# Instantiate the Profanity class:
p = Profanity("sample_transcript.txt", "profanity_wordlist.txt")
# Apply the profanity filter.
censored_transcript = p.apply_filter()
print(censored_transcript)
You can use self.censored_transcript in all places inside your class - self refers to current object of class. Each created object of your class will store self self set of variables available.
censored_transcript without self treated as regular local variable which will be newly created for each call of method.
Error cause:
When method def apply_filter(self) gets called from outer .py file, if __name__ == "__main__" check will be false and local variable censored_transcript will not be created inside this method. So, return censored_transcript tries to return local variable with unassigned value and fails.
Solution 1: in apply_filter(self) you can use object's censored_transcript, not local, to save result. Just append self. before it. And you do not need to return something from this method:
from better_profanity import profanity
class Profanity(object):
def __init__(self, transcript_filename, wordlist_filename):
self.__transcript_filename = transcript_filename
self.__wordlist_filename = wordlist_filename
self.__transcript = self.__load_transcript()
self.apply_filter() # changed
def __load_transcript(self):
f = open(self.__transcript_filename, "r")
file = f.read()
f.close()
return file
# changed
def apply_filter(self):
profanity.load_censor_words_from_file(self.__wordlist_filename)
self.censored_transcript = profanity.censor(self.__transcript)
Solution 2: use a local variable, but assign value to it without if. Or even omit this local variable:
from better_profanity import profanity
class Profanity(object):
def __init__(self, transcript_filename, wordlist_filename):
self.__transcript_filename = transcript_filename
self.__wordlist_filename = wordlist_filename
self.__transcript = self.__load_transcript()
self.censored_transcript = self.apply_filter()
def __load_transcript(self):
f = open(self.__transcript_filename, "r")
file = f.read()
f.close()
return file
# changed
def apply_filter(self):
profanity.load_censor_words_from_file(self.__wordlist_filename)
return profanity.censor(self.__transcript)