Support keep_alive where nurse may be None
For example keep_alive<0,1>() should work where the return value may sometimes be None. At present a "Could not allocate weak reference!" exception is thrown.
Update documentation to clarify behaviour of keep_alive when nurse is None or does not support weak references.
diff --git a/example/example-keep-alive.py b/example/example-keep-alive.py
index ad0176e..187ad53 100644
--- a/example/example-keep-alive.py
+++ b/example/example-keep-alive.py
@@ -31,6 +31,7 @@
gc.collect()
print(p)
p = None
+
gc.collect()
print("")
@@ -43,4 +44,24 @@
gc.collect()
print("")
+
+if True:
+ p = Parent()
+ p.returnNullChildKeepAliveChild()
+ gc.collect()
+ print(p)
+ p = None
+
+gc.collect()
+print("")
+
+if True:
+ p = Parent()
+ p.returnNullChildKeepAliveParent()
+ gc.collect()
+ print(p)
+ p = None
+
+gc.collect()
+print("")
print("Terminating..")