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add var to catch return value of sys.stdout.write

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Mark Pilgrim
2010-09-17 14:23:20 -04:00
parent 6305d1a0b7
commit 7ba05d8b51
1 changed files with 4 additions and 4 deletions
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@@ -464,20 +464,20 @@ AttributeError: 'GzipFile' object has no attribute '__exit__'</samp></pre>
<pre class=screen>
<samp class=p>>>> </samp><kbd class=pp>for i in range(3):</kbd>
<a><samp class=p>... </samp><kbd class=pp> print('PapayaWhip')</kbd> <span class=u>&#x2460;</span></a>
<a><samp class=p>... </samp><kbd class=pp> print('PapayaWhip')</kbd> <span class=u>&#x2460;</span></a>
<samp>PapayaWhip
PapayaWhip
PapayaWhip</samp>
<samp class=p>>>> </samp><kbd class=pp>import sys</kbd>
<samp class=p>>>> </samp><kbd class=pp>for i in range(3):</kbd>
<a><samp class=p>... </samp><kbd class=pp> sys.stdout.write('is the')</kbd> <span class=u>&#x2461;</span></a>
<a><samp class=p>... </samp><kbd class=pp> l = sys.stdout.write('is the')</kbd> <span class=u>&#x2461;</span></a>
<samp>is theis theis the</samp>
<samp class=p>>>> </samp><kbd class=pp>for i in range(3):</kbd>
<a><samp class=p>... </samp><kbd class=pp> sys.stderr.write('new black')</kbd> <span class=u>&#x2462;</span></a>
<a><samp class=p>... </samp><kbd class=pp> l = sys.stderr.write('new black')</kbd> <span class=u>&#x2462;</span></a>
<samp>new blacknew blacknew black</samp></pre>
<ol>
<li>The <code>print()</code> function, in a loop. Nothing surprising here.
<li><code>stdout</code> is defined in the <code>sys</code> module, and it is a <a href=#file-like-objects>stream object</a>. Calling its <code>write()</code> function will print out whatever string you give it. In fact, this is what the <code>print</code> function really does; it adds a carriage return to the end of the string you&#8217;re printing, and calls <code>sys.stdout.write</code>.
<li><code>stdout</code> is defined in the <code>sys</code> module, and it is a <a href=#file-like-objects>stream object</a>. Calling its <code>write()</code> function will print out whatever string you give it, then return the length of the output. In fact, this is what the <code>print</code> function really does; it adds a carriage return to the end of the string you&#8217;re printing, and calls <code>sys.stdout.write</code>.
<li>In the simplest case, <code>sys.stdout</code> and <code>sys.stderr</code> send their output to the same place: the Python <abbr>IDE</abbr> (if you&#8217;re in one), or the terminal (if you&#8217;re running Python from the command line). Like standard output, standard error does not add carriage returns for you. If you want carriage returns, you&#8217;ll need to write carriage return characters.
</ol>