f



local variable referenced before assignment #2

Quick question, probably quite a simple matter. Take the follow start of 
a method:


def review(filesNeedingReview):

     for item in filesNeedingReview:
         (tightestOwner, logMsg) = item

         if (logMsg != None):
             for logInfo in logMsg.changed_paths:


This generates the error:

   UnboundLocalError: local variable 'logMsg' referenced before assignment

I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
so in the python interpreter complaining about the fact this assignment 
might not go well?

Thanks!
0
none3249 (5)
10/25/2007 9:02:24 AM
comp.lang.python 77058 articles. 3 followers. Post Follow

10 Replies
254 Views

Similar Articles

[PageSpeed] 24

On 2007-10-25, Pete Bartonly <none@try.invalid> wrote:
>
> Quick question, probably quite a simple matter. Take the follow start of 
> a method:
>
>
> def review(filesNeedingReview):
>
>      for item in filesNeedingReview:
>          (tightestOwner, logMsg) = item
>
>          if (logMsg != None):
>              for logInfo in logMsg.changed_paths:
>
>
> This generates the error:
>
>    UnboundLocalError: local variable 'logMsg' referenced before assignment

This should work, are you sure you didn't make a typo in one of the names?

Another way to make this fail would be when the if-condition is outside
the loop (is the indentation correct in your code?).

A short demontration:
>>> def r(fnr):
....   for item in fnr:
....     w,m = item
....     if m == 2:
....       print w
....
>>> fnr = [(1,2), (3,4)]
>>> r(fnr)
1

With respect to compactness and style, you can move your multi-assignment
statement in the for loop, as in

for tightestOwner, logMsg in filesNeedingReview:

Also, brackets around conditions (in the if) are not needed, and comparing
against None is usually done with 'is' or 'is not' instead of '==' or '!='.
The result is then

if logMsg is not None:


> I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
> so in the python interpreter complaining about the fact this assignment 
> might not go well?

No, you'd get an error at that point in that case.


Sincerely,
Albert
0
hat7736 (107)
10/25/2007 9:16:09 AM
Pete Bartonly wrote:

> Quick question, probably quite a simple matter. Take the follow start of 
> a method:
> 
> 
> def review(filesNeedingReview):
> 
>      for item in filesNeedingReview:
>          (tightestOwner, logMsg) = item
> 
>          if (logMsg != None):
>              for logInfo in logMsg.changed_paths:
> 
> 
> This generates the error:
> 
>    UnboundLocalError: local variable 'logMsg' referenced before assignment
> 
> I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
> so in the python interpreter complaining about the fact this assignment 
> might not go well?

My crystal ball tells me that you are not posting the actual code where
for... and if... are indented to the same level. This triggers the error
when review() is called with an empty sequence.

Please remember to copy and paste both code and traceback next time.

Peter
0
__peter__ (4031)
10/25/2007 9:18:17 AM
On Oct 25, 10:02 am, Pete Bartonly <n...@try.invalid> wrote:
> Quick question, probably quite a simple matter. Take the follow start of
> a method:
>
> def review(filesNeedingReview):
>
>      for item in filesNeedingReview:
>          (tightestOwner, logMsg) = item
>
>          if (logMsg != None):
>              for logInfo in logMsg.changed_paths:
>
> This generates the error:
>
>    UnboundLocalError: local variable 'logMsg' referenced before assignment

Check your indentation?
Seems to me that you might really have:

def review(...):
    for ...:
        ....
    if (logMsg...):
        ....

HTH

--
Arnaud


0
arnodel (791)
10/25/2007 9:23:03 AM
On 25/10/2007, A.T.Hofkamp <hat@se-162.se.wtb.tue.nl> wrote:
> On 2007-10-25, Pete Bartonly <none@try.invalid> wrote:
> >
> Also, brackets around conditions (in the if) are not needed, and comparing
> against None is usually done with 'is' or 'is not' instead of '==' or '!='.
> The result is then
>
> if logMsg is not None:

Or just

>>>  if logMsg:
            do_something()

:)
0
tdwdotnet (44)
10/25/2007 1:01:13 PM
On 2007-10-25, Tim Williams <tdwdotnet@gmail.com> wrote:
> On 25/10/2007, A.T.Hofkamp <hat@se-162.se.wtb.tue.nl> wrote:
>> On 2007-10-25, Pete Bartonly <none@try.invalid> wrote:
>> >
>> Also, brackets around conditions (in the if) are not needed, and comparing
>> against None is usually done with 'is' or 'is not' instead of '==' or '!='.
>> The result is then
>>
>> if logMsg is not None:
>
> Or just
>
>>>>  if logMsg:
>             do_something()
>
>:)

That is not the same.

If logMsg is 0, False, or empty string, the second variant
would be False and not True.

Albert
0
hat7736 (107)
10/25/2007 1:12:01 PM
A.T.Hofkamp wrote:
> On 2007-10-25, Pete Bartonly <none@try.invalid> wrote:
>> Quick question, probably quite a simple matter. Take the follow start of 
>> a method:
>>
>>
>> def review(filesNeedingReview):
>>
>>      for item in filesNeedingReview:
>>          (tightestOwner, logMsg) = item
>>
>>          if (logMsg != None):
>>              for logInfo in logMsg.changed_paths:
>>
>>
>> This generates the error:
>>
>>    UnboundLocalError: local variable 'logMsg' referenced before assignment
> 
> This should work, are you sure you didn't make a typo in one of the names?

Nope, the above is verbatim. This is why I'm so confused. It should 
work! I'm editing in emacs, and the indents are tab chars. I've 
re-indented the indents using 'tab' key - same result.

The entire error output is this:

Traceback (most recent call last):
   File "checkCode.py", line 602, in ?
     analyseFiles(tempDir)
   File "checkCode.py", line 448, in analyseFiles
     analyseFilesInARepos(startDir, f)
   File "checkCode.py", line 590, in analyseFilesInARepos
     makeReport(projName, filesNeedingReview, filesFailedReview)
   File "checkCode.py", line 422, in makeReport
     for logInfo in logMsg.changed_paths:
UnboundLocalError: local variable 'logMsg' referenced before assignment

I'm rather stuck at what to try next!

thanks.
Pete







> 
> Another way to make this fail would be when the if-condition is outside
> the loop (is the indentation correct in your code?).
> 
> A short demontration:
>>>> def r(fnr):
> ...   for item in fnr:
> ...     w,m = item
> ...     if m == 2:
> ...       print w
> ...
>>>> fnr = [(1,2), (3,4)]
>>>> r(fnr)
> 1
> 
> With respect to compactness and style, you can move your multi-assignment
> statement in the for loop, as in
> 
> for tightestOwner, logMsg in filesNeedingReview:
> 
> Also, brackets around conditions (in the if) are not needed, and comparing
> against None is usually done with 'is' or 'is not' instead of '==' or '!='.
> The result is then
> 
> if logMsg is not None:
> 
> 
>> I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
>> so in the python interpreter complaining about the fact this assignment 
>> might not go well?
> 
> No, you'd get an error at that point in that case.
> 
> 
> Sincerely,
> Albert
0
none3249 (5)
10/25/2007 3:56:11 PM
A.T.Hofkamp wrote:
> On 2007-10-25, Pete Bartonly <none@try.invalid> wrote:
>> Quick question, probably quite a simple matter. Take the follow start of 
>> a method:

> With respect to compactness and style, you can move your multi-assignment
> statement in the for loop, as in
[snip]

Btw, thanks for the tips on style too!
Pete
0
none3249 (5)
10/25/2007 3:57:05 PM
Peter Otten wrote:
> Pete Bartonly wrote:
> 
>> Quick question, probably quite a simple matter. Take the follow start of 
>> a method:
>>
>>
>> def review(filesNeedingReview):
>>
>>      for item in filesNeedingReview:
>>          (tightestOwner, logMsg) = item
>>
>>          if (logMsg != None):
>>              for logInfo in logMsg.changed_paths:
>>
>>
>> This generates the error:
>>
>>    UnboundLocalError: local variable 'logMsg' referenced before assignment
>>
>> I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
>> so in the python interpreter complaining about the fact this assignment 
>> might not go well?
> 
> My crystal ball tells me that you are not posting the actual code where
> for... and if... are indented to the same level. 

I am! See my other reply just now.

Here it the code again, directly cut and pasted from emacs:

     for item in filesNeedingReview:
         (tightestOwner, logMsg) = item

         if (logMsg != None):
             for logInfo in logMsg.changed_paths:
                 if (not tightestOwner in emailListForReviewers):
                     emailListForReviewers.append(tightestOwner)




This triggers the error
> when review() is called with an empty sequence.
> 
> Please remember to copy and paste both code and traceback next time.

Sorry 'bout that. The traceback I forgot is:

Traceback (most recent call last):
   File "checkCode.py", line 599, in ?
     analyseFiles(tempDir)
   File "checkCode.py", line 445, in analyseFiles
     analyseFilesInARepos(startDir, f)
   File "checkCode.py", line 587, in analyseFilesInARepos
     makeReport(projName, filesNeedingReview, filesFailedReview)
   File "checkCode.py", line 419, in makeReport
     for logInfo in logMsg.changed_paths:
UnboundLocalError: local variable 'logMsg' referenced before assignment


Pete
0
none3249 (5)
10/25/2007 3:58:58 PM
Pete Bartonly wrote:
> 
> Quick question, probably quite a simple matter. Take the follow start of 
> a method:
> 
> 
> def review(filesNeedingReview):
> 
>     for item in filesNeedingReview:
>         (tightestOwner, logMsg) = item
> 
>         if (logMsg != None):
>             for logInfo in logMsg.changed_paths:
> 
> 
> This generates the error:
> 
>   UnboundLocalError: local variable 'logMsg' referenced before assignment
> 
> I thought I'd assigned it in the "(tightestOwner, logMsg) = item" line - 
> so in the python interpreter complaining about the fact this assignment 
> might not go well?
> 
> Thanks!

Argh! Mea culpa everyone!
Turns out that there is a similar few lines of code later on in the 
code. I was confusing which was which. (I was using meta-x goto-line but 
then looking at the wrong but somehow, as it appeared on the same screen 
in emacs.)
So the error was occuring at a similar line in the code, but one at 
whihc logMsg *wasn't* being set beforehand.

Sorry all, thanks for your help, appreciate it!
Pete

0
none3249 (5)
10/25/2007 4:11:16 PM
On Thu, 25 Oct 2007 16:58:58 +0100, Pete Bartonly <none@try.invalid>
declaimed the following in comp.lang.python:

> >>
> >> def review(filesNeedingReview):

	^^^^^^^^^^^^^^^^^^

> Here it the code again, directly cut and pasted from emacs:
>
	Better
 
>      for item in filesNeedingReview:
>          (tightestOwner, logMsg) = item
> 
>          if (logMsg != None):
>              for logInfo in logMsg.changed_paths:
>                  if (not tightestOwner in emailListForReviewers):
>                      emailListForReviewers.append(tightestOwner)

> Traceback (most recent call last):
>    File "checkCode.py", line 599, in ?
>      analyseFiles(tempDir)
>    File "checkCode.py", line 445, in analyseFiles
>      analyseFilesInARepos(startDir, f)
>    File "checkCode.py", line 587, in analyseFilesInARepos
>      makeReport(projName, filesNeedingReview, filesFailedReview)
>    File "checkCode.py", line 419, in makeReport
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>      for logInfo in logMsg.changed_paths:
> UnboundLocalError: local variable 'logMsg' referenced before assignment
> 
	Obviously the first post was NOT cut&paste, since the function names
(and parameter signature) have changed...

	Given that, I'd suggest 'tis time to strip down to the absolute
minimum code that still produces the error...
-- 
	Wulfraed	Dennis Lee Bieber		KD6MOG
	wlfraed@ix.netcom.com		wulfraed@bestiaria.com
		HTTP://wlfraed.home.netcom.com/
	(Bestiaria Support Staff:		web-asst@bestiaria.com)
		HTTP://www.bestiaria.com/
0
wlfraed (4596)
10/25/2007 5:08:08 PM
Reply: