From 56adbe7361e421fba5f0c72c233827d39a550507 Mon Sep 17 00:00:00 2001
From: Dustin Spicuzza <dustin@virtualroadside.com>
Date: Wed, 15 Mar 2017 22:06:25 -0400
Subject: [PATCH] Add note about module destructors

- Technique provided by @jagerman
- Fixes #638
---
 docs/advanced/misc.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/docs/advanced/misc.rst b/docs/advanced/misc.rst
index 163fb0ee97..92d77134af 100644
--- a/docs/advanced/misc.rst
+++ b/docs/advanced/misc.rst
@@ -171,6 +171,26 @@ would be then able to access the data behind the same pointer.
 .. [#f6] https://docs.python.org/3/extending/extending.html#using-capsules
 
 
+Module Destructors
+==================
+
+pybind11 does not explicitly provide a mechanism that can be called at module
+destruction time (and most users will not need this functionality). However,
+if you do happen to need the ability to do something when a module is
+destroyed, you can use a Python capsule to accomplish this:
+
+.. code-block:: cpp
+
+    // the capsule needs something to reference
+    static int unused;
+    
+    py::capsule cleanup(&unused, [](PyObject * capsule) {
+        // do cleanup here -- this function is called with the GIL held
+    });
+    
+    m.add_object("_cleanup", cleanup);
+
+
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