bpo-38293: Allow shallow and deep copying of property objects (GH-16438)
Copying property objects results in a TypeError. Steps to reproduce:
```
>>> import copy
>>> obj = property()
>>> copy.copy(obj)
````
This affects both shallow and deep copying.
My idea for a fix is to add property objects to the list of "atomic" objects in the copy module.
These already include types like functions and type objects.
I also added property objects to the unit tests test_copy_atomic and test_deepcopy_atomic. This is my first PR, and it's highly likely I've made some mistake, so please be kind :)
https://bugs.python.org/issue38293
diff --git a/Lib/copy.py b/Lib/copy.py
index f53cd8c..41873f2 100644
--- a/Lib/copy.py
+++ b/Lib/copy.py
@@ -107,7 +107,7 @@
def _copy_immutable(x):
return x
for t in (type(None), int, float, bool, complex, str, tuple,
- bytes, frozenset, type, range, slice,
+ bytes, frozenset, type, range, slice, property,
types.BuiltinFunctionType, type(Ellipsis), type(NotImplemented),
types.FunctionType, weakref.ref):
d[t] = _copy_immutable
@@ -195,6 +195,7 @@
d[types.BuiltinFunctionType] = _deepcopy_atomic
d[types.FunctionType] = _deepcopy_atomic
d[weakref.ref] = _deepcopy_atomic
+d[property] = _deepcopy_atomic
def _deepcopy_list(x, memo, deepcopy=deepcopy):
y = []
diff --git a/Lib/test/test_copy.py b/Lib/test/test_copy.py
index 45a6920..35f72fb 100644
--- a/Lib/test/test_copy.py
+++ b/Lib/test/test_copy.py
@@ -99,7 +99,7 @@
42, 2**100, 3.14, True, False, 1j,
"hello", "hello\u1234", f.__code__,
b"world", bytes(range(256)), range(10), slice(1, 10, 2),
- NewStyle, Classic, max, WithMetaclass]
+ NewStyle, Classic, max, WithMetaclass, property()]
for x in tests:
self.assertIs(copy.copy(x), x)
@@ -357,7 +357,7 @@
pass
tests = [None, 42, 2**100, 3.14, True, False, 1j,
"hello", "hello\u1234", f.__code__,
- NewStyle, Classic, max]
+ NewStyle, Classic, max, property()]
for x in tests:
self.assertIs(copy.deepcopy(x), x)