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From: Ned Batchelder <ned@nedbatchelder.com>
Subject: Re: Question about Pass-by-object-reference?
Date: Tue, 22 Jul 2014 15:32:19 -0400
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On 7/22/14 3:04 PM, fl wrote:
> Hi,
> I learn Python function call on tutorial. There is a link on this subject.
> http://robertheaton.com/2014/02/09/pythons-pass-by-object-reference-as-explained-by-philip-k-dick/
>
> Although it explains clearly, the figure makes me puzzled.
>
> ""Python is different. As we know, in Python, "Object references are passed by
> value".
>
> A function receives a reference to (and will access) the same object in memory as
> used by the caller. However, it does not receive the box that the caller is
> storing this object in; as in pass-by-value, the function provides its own box and
> creates a new variable for itself. Let's try appending again:""
>
> On the figure, it shows that the result is [0, 1]  (Am I right on the figure?)
>

This is a topic that often confuses people new to Python.  The article 
you linked to seems very confusing to me.  My own take on how to explain 
it is here: http://nedbatchelder.com/text/names.html

>
> When I enter the command lines on my computer:
>>>> list=[0]
>>>> append(list)
>>>> print(list)
> [0]
>
> How to understand my result and that figure?

You should have gotten [0, 1], you must have different code than was 
shown in the article.  I recommend putting the code into a .py file, and 
running it all at once.  Then if it doesn't do what you expect, you can 
show the entire .py file when asking for help.

>
>
>
> Thanks,
>


-- 
Ned Batchelder, http://nedbatchelder.com