[Python-3000] A minor cleanup: instances from bound methods
Nick Craig-Wood
nick at craig-wood.com
Tue Apr 18 11:02:15 CEST 2006
I noticed this the other day. Perhaps it is suitable for a python
3000 cleanup? It certainly seems illogical, but probably too
intrusive to change in python 2.x.
I needed to find the instance from a bound method, with obj.im_self.
Eg
>>> class C(object):
... def fn(self): print "hello"
...
>>> c=C()
>>> fn=c.fn
>>> fn
<bound method C.fn of <__main__.C object at 0xb7dd2acc>>
>>> fn.im_self
<__main__.C object at 0xb7dd2acc>
>>> fn.__self__
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'function' object has no attribute '__self__'
>>>
But I discovered that builtin objects work in a completely different
way with obj.__self__, Eg
>>> fd=open("myfile","w")
>>> fn=fd.write
>>> fn
<built-in method write of file object at 0xb7dc1260>
>>> fn.im_self
Traceback (most recent call last):
File "<stdin>", line 1, in ?
AttributeError: 'builtin_function_or_method' object has no attribute 'im_self'
>>> fn.__self__
<open file 'myfile', mode 'w' at 0xb7dc1260>
>>>
I suggest that either im_self or __self__ is renamed!
--
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick
More information about the Python-3000
mailing list