In version of Python prior to 2.5, it would appear that deepcopying
compiled regular expressions worked by accident:
2.4:
>>> copy.deepcopy(re.compile(''))
<_sre.SRE_Pattern object at 0xb7d53ef0>
2.5:
>>> copy.deepcopy(re.compile(''))
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python2.5/copy.py", line 173, in deepcopy
y = copier(memo)
TypeError: cannot deepcopy this pattern object
I say "by accident", since the SRE_Pattern object in 2.4 has
a __deepcopy__ method which raises the "cannot deepcopy this pattern
object" TypeError, however this method isn't found by copy.deepcopy()
in 2.4, and copy.deepcopy() falls back to using the pickle logic.
The _sre source has #ifdef-out support for __deepcopy__, issue 416670
has the gory details:
http://bugs.python.org/issue416670
Changeset 38430 on the release24-maint branch introduced the changes
that stopped SRE_Pattern.__deepcopy__ being found. r38430 was a patch
forward ported from 2.3, but never ported to the trunk (probably a good
thing, too).
Thoughts?
--
Andrew McNamara, Senior Developer, Object Craft
http://www.object-craft.com.au/
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