On 8/15/2015 3:38 PM, Clayton Kirkwood wrote:
top_directory = "/users/Clayton/Pictures"
target_directory = top_directory #directory we are checking
filetypes = ('jpg', 'png', 'avi', 'mp4', 'mov', 'bmp')
imports...
def override_defaults():
with open( user_preferences ) as f:
for line in f.readline():
llist = line.split()
if llist[0] == '#': #comment line to ignore
continue
elif llist[0] == 'top_directory':
if len(llist) == 1:
pass
else:
top_directory = llist[1]
elif llist[0] == 'target_directory':
if len(llist) == 1:
pass
else:
target_directory = llist[1]
else: #assume only filetypes now or until next comment or
other keyword
if llist[0] == 'filetypes': #allow keyword w/wo following
types
if llist.length() == 1:
continue #assume user plans either not
interested in types or types coming on later line
llist.pop([0]) #skip keyword and start
recording
filetypes.append(llist[0:]) #assume line contains 0,
consumes blank lines, or more media files w/wo leading dot
continue
56 return( top_directory, filetypes, target_directory )
80 top_directory, filetypes, target_directory = override_defaults()>
The error message again is:
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
Your explanation doesn't make any sense to me. I'd have thought that
having assigned top_directory at line 10, but then trying to reassign
it at line 80, means that the function now knows nothing about it,
hence the error.
Assigning to a variable inside a function makes that variable local, which
must
have happened as per the error message:
UnboundLocalError: local variable 'top_directory'...
As Peter noted, somewhere within override_defaults there's an assignment
to it. Changing to
def override_defaults(top_directory=top_directory):
should initialize it in case the assignment path isn't processed.
Above is the actual code. The file /user..../user preferences exists but is
empty. Defaults are at the top. For what it is worth, the debugger stopped
in the function shows the values stated as the defaults at the top. If I
understand correctly, the readline() would drop out, but even if it doesn't
no assignments would be made for top_directory or target_directory.
Actual assignment isn't required to make it a local variable -- only the
fact that it appears on the left hand side of an assignment statement
with the function.
I thought that top_directory was global to this file. I am hearing that
it doesn't matter whether the assignment is above or below the function
definition. I should be able to use the tuple for the results of the call,
right? In this case, no assignment was made. If I understand, the function
sees the global.
Not any more -- it's a local variable because the assignment, while not
executed, exists.
If that is changed inside the function, doesn't it change
the global?
Only if you include the globals statement before the variable is referenced.
Emile
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