mirror of
https://github.com/github/codeql.git
synced 2025-12-25 21:26:37 +01:00
41 lines
1.3 KiB
XML
41 lines
1.3 KiB
XML
<!DOCTYPE qhelp PUBLIC
|
|
"-//Semmle//qhelp//EN"
|
|
"qhelp.dtd">
|
|
<qhelp>
|
|
|
|
<overview>
|
|
<p> If a file is opened then it should always be closed again, even if an
|
|
exception is raised.
|
|
Failing to ensure that all files are closed may result in failure due to too
|
|
many open files.</p>
|
|
|
|
</overview>
|
|
<recommendation>
|
|
|
|
<p>Ensure that if you open a file it is always closed on exiting the method.
|
|
Wrap the code between the <code>open()</code> and <code>close()</code>
|
|
functions in a <code>with</code> statement or use a <code>try...finally</code>
|
|
statement. Using a <code>with</code> statement is preferred as it is shorter
|
|
and more readable.</p>
|
|
|
|
</recommendation>
|
|
<example>
|
|
<p>The following code shows examples of different ways of closing a file. In the first example, the
|
|
file is closed only if the method is exited successfully. In the other examples, the file is always
|
|
closed on exiting the method.</p>
|
|
|
|
<sample src="FileNotAlwaysClosed.py" />
|
|
|
|
</example>
|
|
<references>
|
|
|
|
|
|
<li>Python Language Reference: <a href="http://docs.python.org/reference/compound_stmts.html#the-with-statement">The with statement</a>,
|
|
<a href="http://docs.python.org/reference/compound_stmts.html#the-try-statement">The try statement</a>.</li>
|
|
<li>Python PEP 343: <a href="http://www.python.org/dev/peps/pep-0343">The "with" Statement</a>.</li>
|
|
|
|
|
|
|
|
</references>
|
|
</qhelp>
|