Re-defined variable from outer scope PYL-W0621
Anti-pattern
Major
4 years ago
—
4 years old
Redefining name 'results' from outer scope (line 144)
106 [pipeline(testcase)() for testcase in testcases]
107
108 # Or, you can also award partial credit for each testcase:
109 results = PartialCredit(map(pipeline, testcases), 10)()110 self.score = results.score
111
112 # Any output written to stdout or stderr is captured and includedRedefining name 'results' from outer scope (line 144)
128
129 self.weight = 10
130
131 results = Pipeline(Run(["echo", "hello world"]), AssertExitSuccess())()132 # Here we set the leaderboard score as the duration.
133 self.leaderboardScore = results.duration
134
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()