Re-defined variable from outer scope PYL-W0621
Anti-pattern
Major
2 years ago
—
2 years old
Redefining name 'watchlist' from outer scope (line 118)
124 watchlist_resp = requests.get(
125 "https://api.seesaw.abc.net.au/v1/saved/watchlist/show?source=iview&slug=watchlist&raw=1&done=0&UID="+uid)
126 if watchlist_resp.status_code == 200:
127 watchlist = json.loads(watchlist_resp.content.decode())128 fg = FeedGenerator()
129 fg.id('https://iview-rss.maxstuff.net/watchlist/'+uid)
130 fg.title("iView Watchlist "+uid[:8])
Description
The local variable name hides the variable defined in the outer scope, making it inaccessible and might confuse.
Bad practice
filename = 'myfile.txt'
def read_file(filename): # This shadows the global `filename`
with open(filename) as file:
return file.readlines()
Preferred:
FILENAME = 'myfile.txt' # renamed global to UPPER_CASE as convention
def read_file(filename):
with open(filename) as file:
return file.readlines()
Bad practice
Another usual suspect of this is when you use the same parameter name inside a function as the global variable you are using. For example:
def run_app(app):
# This `app` shadows the global app...
app.run()
if __name__ == '__main__':
app = MyApp() # This is a global variable!
run_app(app)
Preferred:
To avoid this re-defining of a global, consider not defining app as a global, but inside a main() function instead:
def run_app(app):
# There is no longer a global `app` variable.
app.run()
def main():
app = MyApp()
run_app(app)
if __name__ == '__main__':
main()