Why copy constructor and assignment operator are disallowed?
<pre><code>#undef GOOGLE_DISALLOW_EVIL_CONSTRUCTORS
#define GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(TypeName)    \
   TypeName(const TypeName&amp;);                           \
   void operator=(const TypeName&amp;)
</code></pre>

<p>I'm, reading open source code from google.
Why copy  constructor and assignment operator are disallowed?</p>
