them sparingly in regular
code, e.g. when all types are actually fixed.
</p>

<h2 id="gc">Garbage Collection of cdata Objects</h2>
<p>
All explicitly (<tt>ffi.new()</tt>, <tt>ffi.cast()</tt> etc.) or
implicitly (accessors) created cdata objects are garbage collected.
You need to ensure to retain valid references to cdata objects
somewhere on a Lua stack, an upvalue or in a Lua table while they are
still in use. Once the last reference to a cdata object is gone, the
garbage collector will automatically free 