DefineEqualsWhenAddingAttributes.qhelp

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

<overview>
<p>A class that defines attributes that are not present in its superclasses
may need to override the <code>__eq__()</code> method (<code>__ne__()</code>
should also be defined).</p>

<p>Adding additional attributes without overriding  <code>__eq__()</code> means
that the additional attributes will not be accounted for in equality tests.</p>


</overview>
<recommendation>

<p>Override the <code>__eq__</code> method.</p>


</recommendation>
<example>
<p>In the following example the <code>ColorPoint</code>
class subclasses the <code>Point</code> class and adds a new attribute,
but does not override the <code>__eq__</code> method.
</p>

<sample src="DefineEqualsWhenAddingAttributes.py" />


</example>
<references>

<li>Peter Grogono, Philip Santas: <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.48.5109&amp;rep=rep1&amp;type=pdf">Equality in Object Oriented Languages</a></li>

</references>
</qhelp>