FFI: Check for __new metamethod when calling a constructor.

1 files changed, 9 insertions, 3 deletions

diff --git a/doc/ext_ffi_semantics.html b/doc/ext_ffi_semantics.html
index 4b498fbe..d0613aed 100644
--- a/doc/ext_ffi_semantics.html
+++ b/doc/ext_ffi_semantics.html
@@ -599,8 +599,9 @@ C type pointed to by the reference.
 </p>
 <p>
 The pre-defined operations are always tried first before deferring to a
-metamethod or index table (if any) for the corresponding ctype. An error
-is raised if the metamethod lookup or index table lookup fails.
+metamethod or index table (if any) for the corresponding ctype (except
+for <tt>__new</tt>). An error is raised if the metamethod lookup or
+index table lookup fails.
 </p>
 
 <h3 id="cdata_array">Indexing a cdata object</h3>
@@ -669,7 +670,12 @@ to <tt>foo.c</tt>.
 <ul>
 
 <li><b>Constructor</b>: a ctype object can be called and used as a
-<a href="ext_ffi_api.html#ffi_new">constructor</a>.</li>
+<a href="ext_ffi_api.html#ffi_new">constructor</a>. This is equivalent
+to <tt>ffi.new(ct, ...)</tt>, unless a <tt>__new</tt> metamethod is
+defined. The <tt>__new</tt> metamethod is called with the ctype object
+plus any other arguments passed to the contructor. Note that you have to
+use <tt>ffi.new</tt> inside of it, since calling <tt>ct(...)</tt> would
+cause infinite recursion.</li>
 
 <li><b>C&nbsp;function call</b>: a cdata function or cdata function
 pointer can be called. The passed arguments are