CompareConstants.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>


<overview>
<p>When two constants are compared it is typically an
indication of a mistake, since the Boolean value of the comparison
will always be the same. In very old code this may be used to initialize
<code>True</code> and <code>False</code>.</p>

</overview>
<recommendation>

<p>It is never good practice to compare a value with itself. If the constant
behavior is indeed required, use the Boolean literals <code>True</code> or
<code>False</code>, rather than encoding them obscurely as <code>1 == 1</code>
or similar. If there is a mistake, ascertain the desired behavior and correct it.
</p>

</recommendation>
<example>

<p>In this example, old code uses <code>1==1</code> to initialize <code>__builtins__.True</code>.
This code has been unnecessary on all versions of Python released since 2003 and can be deleted.
</p><sample src="CompareConstants.py" />

</example>
<references>

<li>Python Language Reference: <a href="http://docs.python.org/2/reference/expressions.html#not-in">Comparisons</a>.</li>

</references>
</qhelp>