On 11/1/14 12:56 PM, duncan smith wrote:
Hello,
I have a Bloom filter class and want to (partially) serialize
instances using hex() or oct(). Instances are mutable, so I can't
inherit from long. I thought I'd found the answer when I came across
__index__,
https://docs.python.org/2/reference/datamodel.html#object.__index__. But
it doesn't seem to work as I expected it to.
class MyClass(object):
def __init__(self):
self.val = 7
def __index__(self):
return self.val
x = MyClass()
oct(x)
Traceback (most recent call last):
File "<pyshell#76>", line 1, in <module>
oct(x)
TypeError: oct() argument can't be converted to oct
oct(x.__index__())
'07'
Can someone please explain why my thinking is wrong on this? TIA.
Just above your link in the docs is __oct__ and __hex__, which are used
to implement oct() and hex():
https://docs.python.org/2/reference/datamodel.html#object.__oct__
That said, I would simply add a .hex() method on the class. I would
never expect a complex thing like a Bloom filter to be turned into
useful hex with the hex() builtin.
For example, when making an MD5 hash, you use the md5.hexdigest()
method, not hex(md5).
--
Ned Batchelder, http://nedbatchelder.com
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