minor fixes to PR #368

docs/advanced.rst

@@ -947,32 +947,30 @@ within pybind11.
 Classes with non-public destructors
 Classes with non-public destructors
 ===================================
 ===================================
 
 
-If a class has a private or protected destructor, as might be the case in a singleton
-pattern for example, a compile error will occur when trying to expose the class because
-the std::unique_ptr holding the instance of the class will attempt to call its destructor
-when de-allocating the instance. In order to expose classes with private or protected
-destructors you can override the ``holder_type`` and provide a custom destructor. Pybind11
-provides a blank destructor for you to use as follows
+If a class has a private or protected destructor (as might e.g. be the case in
+a singleton pattern), a compile error will occur when creating bindings via
+pybind11. The underlying issue is that the ``std::unique_ptr`` holder type that
+is responsible for managing the lifetime of instances will reference the
+destructor even if no deallocations ever take place. In order to expose classes
+with private or protected destructors, it is possible to override the holder
+type via the second argument to ``class_``. Pybind11 provides a helper class
+``py::nodelete`` that disables any destructor invocations. In this case, it is
+crucial that instances are deallocated on the C++ side to avoid memory leaks.
 
 
 .. code-block:: cpp
 .. code-block:: cpp
 
 
     /* ... definition ... */
     /* ... definition ... */
 
 
     class MyClass {
     class MyClass {
-        ~MyClass() {}
+    private:
+        ~MyClass() { }
     };
     };
 
 
     /* ... binding code ... */
     /* ... binding code ... */
 
 
-    py::class_<MyClass, std::unique_ptr<MyClass, py::blank_deleter<MyClass>>(m, "MyClass")
+    py::class_<MyClass, std::unique_ptr<MyClass, py::nodelete>>(m, "MyClass")
         .def(py::init<>)
         .def(py::init<>)
 
 
-The blank destructor provided by Pybind11 is a no-op, so you will still need to make sure
-you are cleaning up the memory in C++. Additionally, the blank destructor, or any custom
-destructor you provide to the unique_ptr will only be called if the object is initialized
-within Python. If the object is initialized in C++ via a getter function, the deleter will
-not be called at all.
-
 .. _catching_and_throwing_exceptions:
 .. _catching_and_throwing_exceptions:
 
 
 Catching and throwing exceptions
 Catching and throwing exceptions

include/pybind11/common.h

@@ -350,11 +350,7 @@ PYBIND11_DECL_FMT(float, "f");
 PYBIND11_DECL_FMT(double, "d");
 PYBIND11_DECL_FMT(double, "d");
 PYBIND11_DECL_FMT(bool, "?");
 PYBIND11_DECL_FMT(bool, "?");
 
 
-// Helper class for exposing classes with a private destructor by overriding the deleter object of std::unique_ptr
-template <typename T>
-struct blank_deleter
-{
-    void operator()(T*) {}
-};
+/// Dummy destructor wrapper that can be used to expose classes with a private destructor
+struct nodelete { template <typename T> void operator()(T*) { } };
 
 
 NAMESPACE_END(pybind11)
 NAMESPACE_END(pybind11)