Message371813
| Author |
vstinner |
| Recipients |
corona10, eric.snow, erlendaasland, pablogsal, phsilva, shihai1991, skrah, vstinner |
| Date |
2020年06月18日.14:06:36 |
| SpamBayes Score |
-1.0 |
| Marked as misclassified |
Yes |
| Message-id |
<1592489196.72.0.133874484646.issue40077@roundup.psfhosted.org> |
| In-reply-to |
| Content |
PR 20960 (_bz2 module) triggers an interesting question. The effect of converting a static type to a heap type on pickle, especially for protocols 0 and 1.
pickle.dumps(o, 0) calls object.__reduce__(o) which calls copyreg._reduce_ex(o, 0).
copyreg._reduce_ex() behaves differently on heap types:
...
for base in cls.__mro__:
if hasattr(base, '__flags__') and not base.__flags__ & _HEAPTYPE:
break
else:
base = object # not really reachable
...
There are 3 things which impacts serialization/deserialization:
- Py_TPFLAGS_HEAPTYPE flag in the type flags
- Is __new__() overriden in the type?
- Py_TPFLAGS_BASETYPE flag in the type flags
Examples:
* In Python 3.7, _random.Random() cannot be serialized because it's a static type (it doesn't have (Py_TPFLAGS_HEAPTYPE)
* In master, _random.Random() cannot be deserialized because _random.Random() has __new__() method (it's not object.__new__()) |
|