Re-defined variable from outer scope PYL-W0621
Anti-pattern
Major
10 months ago
—
4 years old
Redefining name 'context' from outer scope (line 107)
73 return False
74
75
76def limitNbrInsts(gdgtCol, gadget, context): 77 bound = gadget.gadgetMatrix.nbrInsts
78 return limit(gdgtCol, gadget, bound, context)
79Redefining name 'context' from outer scope (line 107)
78 return limit(gdgtCol, gadget, bound, context)
79
80
81def limitNbrBytes(gdgtCol, gadget, context): 82 bound = len(gadget.bytes())
83 return limit(gdgtCol, gadget, bound, context)
84Redefining name 'context' from outer scope (line 107)
83 return limit(gdgtCol, gadget, bound, context)
84
85
86def limitCost(gdgtCol, gadget, context): 87 bound = gadget.cost()
88 return limit(gdgtCol, gadget, bound, context)
89Redefining name 'context' from outer scope (line 107)
61]
62
63
64def limit(gdgtCol, gadget, bound, context): 65 if bound < context:
66 gdgtcpy = gadget.copy()
67 gdgtCol.add_gadget(gdgtcpy)
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()