'generator ignored GeneratorExit''

[Hans Mulder]

On 21/10/12 01:41:37, Charles Hixson wrote:
> On 10/20/2012 04:28 PM, Ian Kelly wrote:
>> On Sat, Oct 20, 2012 at 2:03 PM, Charles Hixson
>> <charleshixsn at earthlink.net>  wrote:
>>> If I run the following code in the same module, it works correctly,
>>> but if I
>>> import it I get the message:
>>> Exception RuntimeError: 'generator ignored GeneratorExit' in<generator
>>> object getNxtFile at 0x7f932f884f50>  ignored
>>>
>>> def getNxtFile (startDir, exts = ["txt", "utf8"]):
>>>      try:
>>>          for    path    in    getNxtPath (startDir, exts):
>>>              try:
>>>                  fil    =    open (path, encoding = "utf-8-sig")
>>>                  yield    fil
>>>              except:
>>>                  print ("Could not read:  ", path)
>>>      except    GeneratorExit:
>>>          raise    StopIteration
>>>
>>> The message appears to be purely informational, but I *would* like to
>>> fix
>>> whatever problem it's reporting, and none of the changes that I've tried
>>> have worked.  What *should* I be doing?
>> The bare except is probably catching the GeneratorExit exception and
>> swallowing it.  Try catching a more specific exception like OSError or
>> even just Exception instead.
>>
>> Also, you don't need to explicitly catch GeneratorExit just to raise
>> StopIteration.  The generator will normally stop on GeneratorExit,
>> provided the exception is actually able to propagate up.
> Thank you.  That was, indeed the problem.  Removing all the try ...
> excepts made it work on my test case.  Now I've got to figure out what
> to catch in case it's not a utf8 file.  I guess that I'll hope that
> IOError will work, as nothing else sounds reasonable.  It's general
> enough that it ought to work.

I would expect a UnicideError, which is a subclass of ValueError,
but not of IOError.  And I'd expect it to be raised when you start
reading the file, not when you open it.

The easiest way to find out this sort of thing, is to not have any
"except" clauses in your code.  That way, the interpreter will tell
you exactly what was raised, and where.  Much easier than guessing.

>>> import sys
>>> fil = open(sys.executable, encoding="utf8")
>>> fil.readline()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File
"/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/codecs.py",
line 300, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xca in position 0:
invalid continuation byte

As I expected, opening a non-utf8 file succeeds, but readline() fails.

Hope this helps,

-- HansM