e
<a href="ext_ffi_api.html#ffi_gc"><tt>ffi.gc()</tt></a>). Pointers to
cdata objects are indistinguishable from pointers returned by C
functions (which is one of the reasons why the GC cannot follow them).
</p>

<h2 id="callback">Callbacks</h2>
<p>
The LuaJIT FFI automatically generates special callback functions
whenever a Lua function is converted to a C&nbsp;function pointer. This
associates the generated callback function pointer with the C&nbsp;type
of the function pointer and the Lua function object 