Clayton Kirkwood wrote: > 10 top_directory = "/users/Clayton/Pictures" > > def override_defaults(): > 56 return( top_directory, filetypes, target_directory ) > > 80 top_directory, filetypes, target_directory = override_defaults() > > > File "C:/Users/Clayton/python/find picture duplicates/find picture > duplicates", line 80, in <module> > top_directory, filetypes, target_directory = override_defaults() > File "C:/Users/Clayton/python/find picture duplicates/find picture > duplicates", line 56, in override_defaults > return( top_directory, filetypes, target_directory ) > UnboundLocalError: local variable 'top_directory' referenced before > assignment > > I am facing the above error: > 10 occurs first > 80 then runs > 56 appears to not work, the function logically does nothing > I thought that variables in the main were visible to defined functions in > the same file, as long as the assignment occurs physically before use.
I don't think it's relevant here, but generally speaking the order in the file doesn't matter, only the order of execution matters. For example >>> def f(): return x ... >>> x = 42 >>> >>> print(f()) 42 Even though the assignment to x occurs physically after the function definition, as the function is invoked after that assignment you don't get a NameError. > When debugging, inside of override_defaults sees the correct value. > What am I not seeing? There must be an assignment to top_directory inside override_defaults(). This assignment turns top_directory into a local variable: >>> def f(): ... if False: x = 42 # this turns x into a local name ... return x ... >>> x = 42 >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 3, in f UnboundLocalError: local variable 'x' referenced before assignment >>> x # the global x is defined, but not visible inside the function 42 Wether a name is local to the function or global is determined statically by the compiler. This is different from class definitions. Compare: >>> x = 42 >>> class A: x = x ... >>> A.x 42 >>> def f(): x = x ... >>> f() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 1, in f UnboundLocalError: local variable 'x' referenced before assignment _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
