[Python-Dev] Re: python3 -bb and hash collisions
Am 11.09.19 um 15:34 schrieb Daniel Holth:
It's different. One hint is that there's already an option to disable
the feature. The old style of error will occasionally reveal itself
with decode errors but the new style error happens silently, you
discover it somehow, then enable the -bb option, track down the source
of the error, and deal with the fallout. The proposed change would
allow `print(bytes)` for (de)bugging by letting you toggle `python3
-bb` behavior at runtime instead of only at the command line. Or you
could debug more explicitly by `print(bytes.decode('ebcdic'))` or
`print(repr(bytes))`
I didn't realize you could override __builtins__.str. That's interesting.
Being able to call str() on everything is such a fundamental assumption
that changing the behavior of str(bytes) would break Python. Porting
from Python 2 to Python 3 is a big task and especially the
str/unicode/bytes handling needs extra care, and this is one of those
corner cases that might prove problematic when porting. That doesn't
justify breaking Python, especially not for those users that have
decided to port to Python 3 in a timely manner.
- Sebastian
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[Python-Dev] Re: python3 -bb and hash collisions
On Wed, Sep 11, 2019 at 09:34:07AM -0400, Daniel Holth wrote: > I didn't realize you could override __builtins__.str. That's interesting. Don't touch __builtins__ that's a CPython implementation detail. The public API is to ``import builtins`` and use that. This override technique is called monkey-patching, it's permitted but considered a fairly dubious thing to do in production code, since it risks breaking other libraries or even parts of your own code which relies on str(b'') working. It may be better to isolate the monkey-patch to the module (hopefully there is only one!) that needs it, by a simple global that shadows the built-in: import builtins def str(obj): assert not isinstance(obj, bytes) return builtins.str(obj) instead of putting it into builtins itself. -- Steven ___ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/YXVMSJPQ7RTDQRQQ77NXHMYYV57K2OCI/
[Python-Dev] Re: python3 -bb and hash collisions
On 10Sep2019 10:42, Daniel Holth wrote: [...] I stopped using Python 3 after learning about str(bytes) by finding it in my corrupted database. [...] Could you outline how this happened to you? Cheers, Cameron Simpson ___ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/47XIWHCI43C5CA3AG4PSOPAZM4KNC7ZS/
[Python-Dev] Re: python3 -bb and hash collisions
On Fri., 13 Sep. 2019, 7:21 am Steven D'Aprano, wrote: > On Wed, Sep 11, 2019 at 09:34:07AM -0400, Daniel Holth wrote: > > > I didn't realize you could override __builtins__.str. That's interesting. > > Don't touch __builtins__ that's a CPython implementation detail. The > public API is to ``import builtins`` and use that. > > This override technique is called monkey-patching, it's permitted but > considered a fairly dubious thing to do in production code, since it > risks breaking other libraries or even parts of your own code which > relies on str(b'') working. > > It may be better to isolate the monkey-patch to the module (hopefully > there is only one!) that needs it, by a simple global that shadows the > built-in: > > import builtins > def str(obj): > assert not isinstance(obj, bytes) > return builtins.str(obj) > > instead of putting it into builtins itself. > In a lot of cases like this, the problems aren't with directly calling str(), but calling third party APIs that indirectly call str(). One nice thing a debugging str() monkey patch can do that the -bb command line switch can't is be selective in when it fails, by inspecting the frame stack for the modules of interest before throwing an exception. Cheers, Nick. > ___ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-le...@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/PC6UI6RSTGLWBRVOLII7KFDGJLD56SNU/
