[Tutor] Pickling in plain English

[Tom Cloyd]

I just want to take a moment to express my deep appreciation for this  
List. As one who is learning Python as amateur, in my spare moments, and  
already getting it to do good work for me, these clear, beautifully worked  
descriptions of basic aspects of Python are simply an ongoing delight for  
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you so very much.

Tom Cloyd

On Tue, 24 May 2005 16:32:50 -0700, <jfouhy at paradise.net.nz> wrote:

> Quoting Tom Tucker <tktucker at gmail.com>:
>
>> I am having trouble understanding the c|Pickle modules. What does
>> serializing and de-serializing objects mean? I have read the below
>> urls and I "think" I understand the process, but I can't visualize the
>> beneifts. Can someone kindly explain pickling in lamens terms?
>
> It's actually astonishingly simple, once you get the hang of it.
>
> example:
>
>>>> arr = [1, 3, 5, 7]
>>>> dct = {'foo':1, 'bar':2, 'baz':3}
>>>> st = "re: your mail"
>>>>
>>>> import pickle
>>>> f = file('dump', 'wb')
>>>> pickle.dump((arr, dct, st), f)
>>>> f.close()
>>>> ^Z
>
> [new instance of python]
>
>>>> import pickle
>>>> f = file('dump', 'r')
>>>> res = pickle.load(f)
>>>> res
> ([1, 3, 5, 7], {'bar': 2, 'foo': 1, 'baz': 3}, 're: your mail')
>
> [and you can look at the file 'dump' on your HDD, if you want to]
>
> Basically, pickle allows you to write any python object to disk and the  
> load it
> back again with very little effort.  This is important if you want your  
> program
> to be able to save state between instances.
>
> You can pickle more complex objects; the only restriction is that  
> pickle.load
> must be able to find the module where the classes are defined.
>
> [there are some other restrictions, but you can do a lot without  
> worrying about
> them]
>
> Does this help?
>



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Tom Cloyd
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