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equality / identity comparison

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Mark Pilgrim
2009-09-02 15:07:51 -04:00
parent 60b645aab7
commit 75a29a1fa6
1 changed files with 4 additions and 1 deletions
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serializing.html
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@@ -148,7 +148,9 @@ NameError: name 'entry' is not defined</samp>
<samp class=p>... </samp>
<a><samp class=p>>>> </samp><kbd class=pp>entry2 == entry</kbd> <span class=u>&#x2463;</span></a>
<samp class=pp>True</samp>
<a><samp class=p>>>> </samp><kbd class=pp>entry2['tags']</kbd> <span class=u>&#x2464;</span></a>
<a><samp class=p>>>> </samp><kbd class=pp>entry2 is entry</kbd> <span class=u>&#x2463;</span></a>
<samp class=pp>False</samp>
<a><samp class=p>>>> </samp><kbd class=pp>entry2['tags']</kbd> <span class=u>&#x2465;</span></a>
<samp class=pp>('diveintopython', 'docbook', 'html')</samp>
<samp class=p>>>> </samp><kbd class=pp>entry2['internal_id']</kbd>
<samp class=pp>b'\xDE\xD5\xB4\xF8'</samp></pre>
@@ -157,6 +159,7 @@ NameError: name 'entry' is not defined</samp>
<li>Open the <code>entry.pickle</code> file.
<li>Load the serialized data into a new variable, <var>entry2</var>.
<li>Python confirms that the two dictionaries, <var>entry</var> and <var>entry2</var>, are equal. In this shell, you built <var>entry</var> from the ground up, starting with an empty dictionary and manually assigning values to specific keys. You serialized this dictionary and stored it in the <code>entry.pickle</code> file. Now you&#8217;ve read the serialized data from that file and created a perfect replica of the original data structure.
<li>Equality is not the same as identity. I said you&#8217;ve created a <em>perfect replica</em> of the original data structure, which is true. But it&#8217;s still a copy.
<li>For reasons that will become clear later in this chapter, I want to point out that the value of the <code>'tags'</code> key is a tuple, and the value of the <code>'internal_id'</code> key is a <code>bytes</code> object.
</ol>