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Date: Wed, 17 Apr 2013 14:36:34 -0400
From: Ned Batchelder <ned@nedbatchelder.com>
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To: 88888 Dihedral <dihedral88888@googlemail.com>
Subject: Re: a couple of things I don't understand wrt lists
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On 4/17/2013 12:10 PM, 88888 Dihedral wrote:
> Serhiy Storchaka於 2013年4月17日星期三UTC+8下午5時35分07秒寫道：
>> 17.04.13 07:57, Larry Hudson написав(ла):
>>
>>> So using a list comprehension you can do it in two lines:
>>> def get_rule(num):
>>>       bs = bin(num)[2:]
>>>       return [0] * (8 - len(bs)) + [int(i) for i in bs]
>>
>>
>> You can do it in one line!
>>
>>
>>
>> def get_rule(num):
>>
>>        return list(map(int, '{:08b}'.format(num)))
> Well, a new object is returned and can be used.
> Then who is going to clean up the object when required?

This is a key thing to understand about Python: memory is managed 
automatically, no one has to clean up the object.  Once there are no 
names referring to the object, it will be cleaned up automatically.

--Ned.