On Dec 8, 9:05 pm, Terry Reedy <tjre...@udel.edu> wrote: > On 12/8/2010 7:11 PM, Ned Deily wrote: > > > > > > > > > > > In article<idosir$45...@dough.gmane.org>, Terry > > Reedy<tjre...@udel.edu> wrote: > >> On 12/8/2010 2:42 PM, Dan wrote: > >>> I have a simple type derived from bytes... > > >>> class atom(bytes): pass > > >>> ... that I cannot deepcopy(). The session below demonstrates > >>> how deepcopy() of "bytes" works fine, but deepcopy() of "atom" > >>> does not. > > [...] > >>> Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) [MSC v.1500 32 > >>> bit (Intel)] Type "help", "copyright", "credits" or "license" for > >>> more information. > >>>>>> import copy class atom(bytes): > >>> ... pass ... > >>>>>> copy.deepcopy(b'abc') > >>> b'abc' > >>>>>> copy.deepcopy(atom(b'abc')) > >>> Traceback (most recent call last): File "C:\Program Files > >>> (x86)\Wing IDE 3.2\src\debug\tserver \_sandbox.py", line 1, > >>> in<module> # Used internally for debug sandbox under external > >>> interpreter File "C:\Python31\Lib\copy.py", line 173, in > >>> deepcopy y = _reconstruct(x, rv, 1, memo) File > >>> "C:\Python31\Lib\copy.py", line 280, in _reconstruct y = > >>> callable(*args) File "C:\Python31\Lib\copyreg.py", line 88, in > >>> __newobj__ return cls.__new__(cls, *args) builtins.TypeError: > >>> string argument without an encoding > > >> You could trace through copy.py and copyreg.py to see where bytes > >> and atom get treated differently. > > >> This might be a bug that should be reported on the tracker, but I > >> do not know. Let see what anyone else says. > > > FWIW, the example still fails with Python 3.1.3 but seems to work OK > > with a recent alpha build of Python 3.2. What specific change might > > have fixed it doesn't come immediately to mind. > > According to difflib.unified_diff, the only difference between > Lib/copy.py from 3.1 to 3.2 is 4 lines: > + > +def _deepcopy_method(x, memo): # Copy instance methods > + return type(x)(x.__func__, deepcopy(x.__self__, memo)) > +_deepcopy_dispatch[types.MethodType] = _deepcopy_method > > (and none in copyreg.py) > > These were added in rev76572 as part ofhttp://bugs.python.org/issue1515 > > Guido decreed this to be a new feature rather than bugfix, so the change > went into future 2.7 and 3.2 and not existing 2.6 and 3.1. > > Tto verify that these cause the change, comment out in 3.2 or add to > 3.1. I have not read through the issue to understand it or why it would > affect the OP's code case. > > -- > Terry Jan Reedy
Thank you everyone. Knowing that it works in 3.2 is good enough for me. I tested the 4 line change anyway...removing it from 3.2 had no detrimental effect, adding it to 3.1 had no effect. It must be something else. Regards, Dan. -- http://mail.python.org/mailman/listinfo/python-list
