Merge pull request #324 from jagerman/example-constructor-tracking

Improve constructor/destructor tracking
2024-11-22 21:25:13 +00:00 · 2016-08-12 00:56:26 +02:00 · 2016-08-12 00:56:26 +02:00 · f4f2afb6c9
commit f4f2afb6c9
parent 85557b1dec 3f589379ec
36 changed files with 969 additions and 495 deletions
--- a/example/CMakeLists.txt
+++ b/example/CMakeLists.txt
@ -60,9 +60,6 @@ foreach(CompilerFlag ${CompilerFlags})
 endforeach()

 set(RUN_TEST ${PYTHON_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/run_test.py)
-if(MSVC OR CMAKE_CXX_COMPILER_ID MATCHES "Intel")
-  set(RUN_TEST ${RUN_TEST} --relaxed)
-endif()

 foreach(VALUE ${PYBIND11_EXAMPLES})
  string(REGEX REPLACE "^(.+).cpp$" "\\1" EXAMPLE_NAME "${VALUE}")
--- a/example/constructor-stats.h
+++ b/example/constructor-stats.h
@ -0,0 +1,243 @@
+#pragma once
+/*
+    example/constructor-stats.h -- framework for printing and tracking object
+    instance lifetimes in example/test code.
+
+    Copyright (c) 2016 Jason Rhinelander <jason@imaginary.ca>
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+
+This header provides a few useful tools for writing examples or tests that want to check and/or
+display object instance lifetimes.  It requires that you include this header and add the following
+function calls to constructors:
+
+    class MyClass {
+        MyClass() { ...; print_default_created(this); }
+        ~MyClass() { ...; print_destroyed(this); }
+        MyClass(const MyClass &c) { ...; print_copy_created(this); }
+        MyClass(MyClass &&c) { ...; print_move_created(this); }
+        MyClass(int a, int b) { ...; print_created(this, a, b); }
+        MyClass &operator=(const MyClass &c) { ...; print_copy_assigned(this); }
+        MyClass &operator=(MyClass &&c) { ...; print_move_assigned(this); }
+
+        ...
+    }
+
+You can find various examples of these in several of the existing example .cpp files.  (Of course
+you don't need to add any of the above constructors/operators that you don't actually have, except
+for the destructor).
+
+Each of these will print an appropriate message such as:
+
+    ### MyClass @ 0x2801910 created via default constructor
+    ### MyClass @ 0x27fa780 created 100 200
+    ### MyClass @ 0x2801910 destroyed
+    ### MyClass @ 0x27fa780 destroyed
+
+You can also include extra arguments (such as the 100, 200 in the output above, coming from the
+value constructor) for all of the above methods which will be included in the output.
+
+For testing, each of these also keeps track the created instances and allows you to check how many
+of the various constructors have been invoked from the Python side via code such as:
+
+    from example import ConstructorStats
+    cstats = ConstructorStats.get(MyClass)
+    print(cstats.alive())
+    print(cstats.default_constructions)
+
+Note that `.alive()` should usually be the first thing you call as it invokes Python's garbage
+collector to actually destroy objects that aren't yet referenced.
+
+For everything except copy and move constructors and destructors, any extra values given to the
+print_...() function is stored in a class-specific values list which you can retrieve and inspect
+from the ConstructorStats instance `.values()` method.
+
+In some cases, when you need to track instances of a C++ class not registered with pybind11, you
+need to add a function returning the ConstructorStats for the C++ class; this can be done with:
+
+    m.def("get_special_cstats", &ConstructorStats::get<SpecialClass>, py::return_value_policy::reference_internal)
+
+Finally, you can suppress the output messages, but keep the constructor tracking (for
+inspection/testing in python) by using the functions with `print_` replaced with `track_` (e.g.
+`track_copy_created(this)`).
+
+*/
+
+#include "example.h"
+#include <unordered_map>
+#include <list>
+#include <typeindex>
+#include <sstream>
+
+class ConstructorStats {
+protected:
+    std::unordered_map<void*, int> _instances; // Need a map rather than set because members can shared address with parents
+    std::list<std::string> _values; // Used to track values (e.g. of value constructors)
+public:
+    int default_constructions = 0;
+    int copy_constructions = 0;
+    int move_constructions = 0;
+    int copy_assignments = 0;
+    int move_assignments = 0;
+
+    void copy_created(void *inst) {
+        created(inst);
+        copy_constructions++;
+    }
+    void move_created(void *inst) {
+        created(inst);
+        move_constructions++;
+    }
+    void default_created(void *inst) {
+        created(inst);
+        default_constructions++;
+    }
+    void created(void *inst) {
+        ++_instances[inst];
+    };
+    void destroyed(void *inst) {
+        if (--_instances[inst] < 0)
+            throw std::runtime_error("cstats.destroyed() called with unknown instance; potential double-destruction or a missing cstats.created()");
+    }
+
+    int alive() {
+        // Force garbage collection to ensure any pending destructors are invoked:
+        py::module::import("gc").attr("collect").operator py::object()();
+        int total = 0;
+        for (const auto &p : _instances) if (p.second > 0) total += p.second;
+        return total;
+    }
+
+    void value() {} // Recursion terminator
+    // Takes one or more values, converts them to strings, then stores them.
+    template <typename T, typename... Tmore> void value(const T &v, Tmore &&...args) {
+        std::ostringstream oss;
+        oss << v;
+        _values.push_back(oss.str());
+        value(std::forward<Tmore>(args)...);
+    }
+    py::list values() {
+        py::list l;
+        for (const auto &v : _values) l.append(py::cast(v));
+        return l;
+    }
+
+    // Gets constructor stats from a C++ type index
+    static ConstructorStats& get(std::type_index type) {
+        static std::unordered_map<std::type_index, ConstructorStats> all_cstats;
+        return all_cstats[type];
+    }
+
+    // Gets constructor stats from a C++ type
+    template <typename T> static ConstructorStats& get() {
+        return get(typeid(T));
+    }
+
+    // Gets constructor stats from a Python class
+    static ConstructorStats& get(py::object class_) {
+        auto &internals = py::detail::get_internals();
+        const std::type_index *t1 = nullptr, *t2 = nullptr;
+        try {
+            auto *type_info = internals.registered_types_py.at(class_.ptr());
+            for (auto &p : internals.registered_types_cpp) {
+                if (p.second == type_info) {
+                    if (t1) {
+                        t2 = &p.first;
+                        break;
+                    }
+                    t1 = &p.first;
+                }
+            }
+        }
+        catch (std::out_of_range) {}
+        if (!t1) throw std::runtime_error("Unknown class passed to ConstructorStats::get()");
+        auto &cs1 = get(*t1);
+        // If we have both a t1 and t2 match, one is probably the trampoline class; return whichever
+        // has more constructions (typically one or the other will be 0)
+        if (t2) {
+            auto &cs2 = get(*t2);
+            int cs1_total = cs1.default_constructions + cs1.copy_constructions + cs1.move_constructions + (int) cs1._values.size();
+            int cs2_total = cs2.default_constructions + cs2.copy_constructions + cs2.move_constructions + (int) cs2._values.size();
+            if (cs2_total > cs1_total) return cs2;
+        }
+        return cs1;
+    }
+};
+
+// To track construction/destruction, you need to call these methods from the various
+// constructors/operators.  The ones that take extra values record the given values in the
+// constructor stats values for later inspection.
+template <class T> void track_copy_created(T *inst) { ConstructorStats::get<T>().copy_created(inst); }
+template <class T> void track_move_created(T *inst) { ConstructorStats::get<T>().move_created(inst); }
+template <class T, typename... Values> void track_copy_assigned(T *, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.copy_assignments++;
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_move_assigned(T *, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.move_assignments++;
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_default_created(T *inst, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.default_created(inst);
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_created(T *inst, Values &&...values) {
+    auto &cst = ConstructorStats::get<T>();
+    cst.created(inst);
+    cst.value(std::forward<Values>(values)...);
+}
+template <class T, typename... Values> void track_destroyed(T *inst) {
+    ConstructorStats::get<T>().destroyed(inst);
+}
+template <class T, typename... Values> void track_values(T *, Values &&...values) {
+    ConstructorStats::get<T>().value(std::forward<Values>(values)...);
+}
+
+inline void print_constr_details_more() { std::cout << std::endl; }
+template <typename Head, typename... Tail> void print_constr_details_more(const Head &head, Tail &&...tail) {
+    std::cout << " " << head;
+    print_constr_details_more(std::forward<Tail>(tail)...);
+}
+template <class T, typename... Output> void print_constr_details(T *inst, const std::string &action, Output &&...output) {
+    std::cout << "### " << py::type_id<T>() << " @ " << inst << " " << action;
+    print_constr_details_more(std::forward<Output>(output)...);
+}
+
+// Verbose versions of the above:
+template <class T, typename... Values> void print_copy_created(T *inst, Values &&...values) { // NB: this prints, but doesn't store, given values
+    print_constr_details(inst, "created via copy constructor", values...);
+    track_copy_created(inst);
+}
+template <class T, typename... Values> void print_move_created(T *inst, Values &&...values) { // NB: this prints, but doesn't store, given values
+    print_constr_details(inst, "created via move constructor", values...);
+    track_move_created(inst);
+}
+template <class T, typename... Values> void print_copy_assigned(T *inst, Values &&...values) {
+    print_constr_details(inst, "assigned via copy assignment", values...);
+    track_copy_assigned(inst, values...);
+}
+template <class T, typename... Values> void print_move_assigned(T *inst, Values &&...values) {
+    print_constr_details(inst, "assigned via move assignment", values...);
+    track_move_assigned(inst, values...);
+}
+template <class T, typename... Values> void print_default_created(T *inst, Values &&...values) {
+    print_constr_details(inst, "created via default constructor", values...);
+    track_default_created(inst, values...);
+}
+template <class T, typename... Values> void print_created(T *inst, Values &&...values) {
+    print_constr_details(inst, "created", values...);
+    track_created(inst, values...);
+}
+template <class T, typename... Values> void print_destroyed(T *inst, Values &&...values) { // Prints but doesn't store given values
+    print_constr_details(inst, "destroyed", values...);
+    track_destroyed(inst);
+}
+template <class T, typename... Values> void print_values(T *inst, Values &&...values) {
+    print_constr_details(inst, ":", values...);
+    track_values(inst, values...);
+}
+
--- a/example/example-buffers.cpp
+++ b/example/example-buffers.cpp
@ -8,35 +8,36 @@
 */

 #include "example.h"
+#include "constructor-stats.h"

 class Matrix {
 public:
    Matrix(size_t rows, size_t cols) : m_rows(rows), m_cols(cols) {
-        std::cout << "Value constructor: Creating a " << rows << "x" << cols << " matrix " << std::endl;
+        print_created(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
        m_data = new float[rows*cols];
        memset(m_data, 0, sizeof(float) * rows * cols);
    }

    Matrix(const Matrix &s) : m_rows(s.m_rows), m_cols(s.m_cols) {
-        std::cout << "Copy constructor: Creating a " << m_rows << "x" << m_cols << " matrix " << std::endl;
+        print_copy_created(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
        m_data = new float[m_rows * m_cols];
        memcpy(m_data, s.m_data, sizeof(float) * m_rows * m_cols);
    }

    Matrix(Matrix &&s) : m_rows(s.m_rows), m_cols(s.m_cols), m_data(s.m_data) {
-        std::cout << "Move constructor: Creating a " << m_rows << "x" << m_cols << " matrix " << std::endl;
+        print_move_created(this);
        s.m_rows = 0;
        s.m_cols = 0;
        s.m_data = nullptr;
    }

    ~Matrix() {
-        std::cout << "Freeing a " << m_rows << "x" << m_cols << " matrix " << std::endl;
+        print_destroyed(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
        delete[] m_data;
    }

    Matrix &operator=(const Matrix &s) {
-        std::cout << "Assignment operator : Creating a " << s.m_rows << "x" << s.m_cols << " matrix " << std::endl;
+        print_copy_assigned(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
        delete[] m_data;
        m_rows = s.m_rows;
        m_cols = s.m_cols;
@ -46,7 +47,7 @@ public:
    }

    Matrix &operator=(Matrix &&s) {
-        std::cout << "Move assignment operator : Creating a " << s.m_rows << "x" << s.m_cols << " matrix " << std::endl;
+        print_move_assigned(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
        if (&s != this) {
            delete[] m_data;
            m_rows = s.m_rows; m_cols = s.m_cols; m_data = s.m_data;
@ -111,5 +112,6 @@ void init_ex_buffers(py::module &m) {
                { sizeof(float) * m.rows(),          /* Strides (in bytes) for each index */
                  sizeof(float) }
            );
-        });
+        })
+        ;
 }
--- a/example/example-buffers.py
+++ b/example/example-buffers.py
@ -30,3 +30,16 @@ for i in range(m4.rows()):
    for j in range(m4.cols()):
        print(m4[i, j], end = ' ')
    print()
+
+from example import ConstructorStats
+cstats = ConstructorStats.get(Matrix)
+print("Instances not destroyed:", cstats.alive())
+m = m4 = None
+print("Instances not destroyed:", cstats.alive())
+m2 = None # m2 holds an m reference
+print("Instances not destroyed:", cstats.alive())
+print("Constructor values:", cstats.values())
+print("Copy constructions:", cstats.copy_constructions)
+#print("Move constructions:", cstats.move_constructions >= 0) # Don't invoke any
+print("Copy assignments:", cstats.copy_assignments)
+print("Move assignments:", cstats.move_assignments)
--- a/example/example-buffers.ref
+++ b/example/example-buffers.ref
@ -1,4 +1,4 @@
-Value constructor: Creating a 5x5 matrix 
+### Matrix @ 0x1df1920 created 5x5 matrix
 0.0
 4.0
 [[ 0.  0.  0.  0.  0.]
@ -10,8 +10,15 @@ Value constructor: Creating a 5x5 matrix
 5.0
 [[ 1.  2.  3.]
 [ 4.  5.  6.]]
-Value constructor: Creating a 2x3 matrix 
+### Matrix @ 0x1fa8cf0 created 2x3 matrix
 1.0 2.0 3.0 
 4.0 5.0 6.0 
-Freeing a 2x3 matrix 
-Freeing a 5x5 matrix 
+Instances not destroyed: 2
+### Matrix @ 0x1fa8cf0 destroyed 2x3 matrix
+Instances not destroyed: 1
+### Matrix @ 0x1df1920 destroyed 5x5 matrix
+Instances not destroyed: 0
+Constructor values: ['5x5 matrix', '2x3 matrix']
+Copy constructions: 0
+Copy assignments: 0
+Move assignments: 0
--- a/example/example-callbacks.cpp
+++ b/example/example-callbacks.cpp
@ -8,6 +8,7 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/functional.h>


@ -57,6 +58,21 @@ void test_dummy_function(const std::function<int(int)> &f) {
    }
 }

+struct Payload {
+    Payload() {
+        print_default_created(this);
+    }
+    ~Payload() {
+        print_destroyed(this);
+    }
+    Payload(const Payload &) {
+        print_copy_created(this);
+    }
+    Payload(Payload &&) {
+        print_move_created(this);
+    }
+};
+
 void init_ex_callbacks(py::module &m) {
    m.def("test_callback1", &test_callback1);
    m.def("test_callback2", &test_callback2);
@ -66,21 +82,6 @@ void init_ex_callbacks(py::module &m) {

    /* Test cleanup of lambda closure */

-    struct Payload {
-        Payload() {
-            std::cout << "Payload constructor" << std::endl;
-        }
-        ~Payload() {
-            std::cout << "Payload destructor" << std::endl;
-        }
-        Payload(const Payload &) {
-            std::cout << "Payload copy constructor" << std::endl;
-        }
-        Payload(Payload &&) {
-            std::cout << "Payload move constructor" << std::endl;
-        }
-    };
-
    m.def("test_cleanup", []() -> std::function<void(void)> { 
        Payload p;

@ -94,4 +95,6 @@ void init_ex_callbacks(py::module &m) {
    m.def("dummy_function2", &dummy_function2);
    m.def("roundtrip", &roundtrip);
    m.def("test_dummy_function", &test_dummy_function);
+    // Export the payload constructor statistics for testing purposes:
+    m.def("payload_cstats", &ConstructorStats::get<Payload>);
 }
--- a/example/example-callbacks.py
+++ b/example/example-callbacks.py
@ -55,6 +55,12 @@ print("func(number=43) = %i" % f(number=43))

 test_cleanup()

+from example import payload_cstats
+cstats = payload_cstats()
+print("Payload instances not destroyed:", cstats.alive())
+print("Copy constructions:", cstats.copy_constructions)
+print("Move constructions:", cstats.move_constructions >= 1)
+
 from example import dummy_function
 from example import dummy_function2
 from example import test_dummy_function
--- a/example/example-callbacks.ref
+++ b/example/example-callbacks.ref
@ -7,7 +7,7 @@ Molly is a dog
 Woof!
 The following error is expected: Incompatible function arguments. The following argument types are supported:
    1. (arg0: example.Dog) -> None
-    Invoked with: <example.Pet object at 0>
+    Invoked with: <example.Pet object at 0x7ffaf4b00db0>
 Callback function 1 called!
 False
 Callback function 2 called : Hello, x, True, 5
@ -19,12 +19,15 @@ False
 func(43) = 44
 func(43) = 44
 func(number=43) = 44
-Payload constructor
-Payload copy constructor
-Payload move constructor
-Payload destructor
-Payload destructor
-Payload destructor
+### Payload @ 0x7ffdcee09c80 created via default constructor
+### Payload @ 0x7ffdcee09c88 created via copy constructor
+### Payload @ 0xb54500 created via move constructor
+### Payload @ 0x7ffdcee09c88 destroyed
+### Payload @ 0x7ffdcee09c80 destroyed
+### Payload @ 0xb54500 destroyed
+Payload instances not destroyed: 0
+Copy constructions: 1
+Move constructions: True
 argument matches dummy_function
 eval(1) = 2
 roundtrip..
@ -36,6 +39,7 @@ could not convert to a function pointer.
 All OK!
 could not convert to a function pointer.
 All OK!
-
 test_callback3(arg0: Callable[[int], int]) -> None
+
 test_callback4() -> Callable[[int], int]
+
--- a/example/example-methods-and-attributes.cpp
+++ b/example/example-methods-and-attributes.cpp
@ -8,32 +8,25 @@
    BSD-style license that can be found in the LICENSE file.
 */

+#include <unordered_map>
+#include <list>
 #include "example.h"
+#include "constructor-stats.h"

 class ExampleMandA {
 public:
-    ExampleMandA() {
-        cout << "Called ExampleMandA default constructor.." << endl;
-    }
-    ExampleMandA(int value) : value(value) {
-        cout << "Called ExampleMandA constructor with value " << value << ".." << endl;
-    }
-    ExampleMandA(const ExampleMandA &e) : value(e.value) {
-        cout << "Called ExampleMandA copy constructor with value " << value << ".." << endl;
-    }
-    ExampleMandA(ExampleMandA &&e) : value(e.value) {
-        cout << "Called ExampleMandA move constructor with value " << value << ".." << endl;
-        e.value = 0;
-    }
-    ~ExampleMandA() {
-        cout << "Called ExampleMandA destructor (" << value << ")" << endl;
-    }
+    ExampleMandA() { print_default_created(this); }
+    ExampleMandA(int value) : value(value) { print_created(this, value); }
+    ExampleMandA(const ExampleMandA &e) : value(e.value) { print_copy_created(this); }
+    ExampleMandA(ExampleMandA &&e) : value(e.value) { print_move_created(this); }
+    ~ExampleMandA() { print_destroyed(this); }
+
    std::string toString() {
        return "ExampleMandA[value=" + std::to_string(value) + "]";
    }

-    void operator=(const ExampleMandA &e) { cout << "Assignment operator" << endl; value = e.value; }
-    void operator=(ExampleMandA &&e) { cout << "Move assignment operator" << endl; value = e.value; e.value = 0;}
+    void operator=(const ExampleMandA &e) { print_copy_assigned(this); value = e.value; }
+    void operator=(ExampleMandA &&e) { print_move_assigned(this); value = e.value; }

    void add1(ExampleMandA other) { value += other.value; }           // passing by value
    void add2(ExampleMandA &other) { value += other.value; }          // passing by reference
@ -88,5 +81,6 @@ void init_ex_methods_and_attributes(py::module &m) {
        .def("internal4", &ExampleMandA::internal4)
        .def("internal5", &ExampleMandA::internal5)
        .def("__str__", &ExampleMandA::toString)
-        .def_readwrite("value", &ExampleMandA::value);
+        .def_readwrite("value", &ExampleMandA::value)
+        ;
 }
--- a/example/example-methods-and-attributes.py
+++ b/example/example-methods-and-attributes.py
@ -35,3 +35,16 @@ print(instance1.internal5())
 print("Instance 1, direct access = %i" % instance1.value)
 instance1.value = 100
 print("Instance 1: " + str(instance1))
+
+from example import ConstructorStats
+
+cstats = ConstructorStats.get(ExampleMandA)
+print("Instances not destroyed:", cstats.alive())
+instance1 = instance2 = None
+print("Instances not destroyed:", cstats.alive())
+print("Constructor values:", cstats.values())
+print("Default constructions:", cstats.default_constructions)
+print("Copy constructions:", cstats.copy_constructions)
+print("Move constructions:", cstats.move_constructions >= 1)
+print("Copy assignments:", cstats.copy_assignments)
+print("Move assignments:", cstats.move_assignments)
--- a/example/example-methods-and-attributes.ref
+++ b/example/example-methods-and-attributes.ref
@ -1,16 +1,16 @@
-Called ExampleMandA default constructor..
-Called ExampleMandA constructor with value 32..
-Called ExampleMandA copy constructor with value 32..
-Called ExampleMandA copy constructor with value 32..
-Called ExampleMandA destructor (32)
-Called ExampleMandA destructor (32)
+### ExampleMandA @ 0x2801910 created via default constructor
+### ExampleMandA @ 0x27fa780 created 32
+### ExampleMandA @ 0x7fff80a98a74 created via copy constructor
+### ExampleMandA @ 0x7fff80a98a78 created via copy constructor
+### ExampleMandA @ 0x7fff80a98a78 destroyed
+### ExampleMandA @ 0x7fff80a98a74 destroyed
 Instance 1: ExampleMandA[value=320]
 Instance 2: ExampleMandA[value=32]
-Called ExampleMandA copy constructor with value 320..
-Called ExampleMandA move constructor with value 320..
-Called ExampleMandA destructor (0)
+### ExampleMandA @ 0x7fff80a98a84 created via copy constructor
+### ExampleMandA @ 0x2801fd0 created via move constructor
+### ExampleMandA @ 0x7fff80a98a84 destroyed
 ExampleMandA[value=320]
-Called ExampleMandA destructor (320)
+### ExampleMandA @ 0x2801fd0 destroyed
 ExampleMandA[value=320]
 ExampleMandA[value=320]
 ExampleMandA[value=320]
@ -22,5 +22,13 @@ ExampleMandA[value=320]
 320
 Instance 1, direct access = 320
 Instance 1: ExampleMandA[value=100]
-Called ExampleMandA destructor (32)
-Called ExampleMandA destructor (100)
+Instances not destroyed: 2
+### ExampleMandA @ 0x2801910 destroyed
+### ExampleMandA @ 0x27fa780 destroyed
+Instances not destroyed: 0
+Constructor values: ['32']
+Default constructions: 1
+Copy constructions: 3
+Move constructions: True
+Copy assignments: 0
+Move assignments: 0
--- a/example/example-modules.cpp
+++ b/example/example-modules.cpp
@ -9,6 +9,7 @@
 */

 #include "example.h"
+#include "constructor-stats.h"

 void submodule_func() {
    std::cout << "submodule_func()" << std::endl;
@ -16,9 +17,10 @@ void submodule_func() {

 class A {
 public:
-    A(int v) : v(v) { std::cout << "A constructor" << std::endl; }
-    ~A() { std::cout << "A destructor" << std::endl; }
-    A(const A&) { std::cout << "A copy constructor" << std::endl; }
+    A(int v) : v(v) { print_created(this, v); }
+    ~A() { print_destroyed(this); }
+    A(const A&) { print_copy_created(this); }
+    A& operator=(const A &copy) { print_copy_assigned(this); v = copy.v; return *this; }
    std::string toString() { return "A[" + std::to_string(v) + "]"; }
 private:
    int v;
@ -26,9 +28,10 @@ private:

 class B {
 public:
-    B() { std::cout << "B constructor" << std::endl; }
-    ~B() { std::cout << "B destructor" << std::endl; }
-    B(const B&) { std::cout << "B copy constructor" << std::endl; }
+    B() { print_default_created(this); }
+    ~B() { print_destroyed(this); }
+    B(const B&) { print_copy_created(this); }
+    B& operator=(const B &copy) { print_copy_assigned(this); a1 = copy.a1; a2 = copy.a2; return *this; }
    A &get_a1() { return a1; }
    A &get_a2() { return a2; }

--- a/example/example-modules.py
+++ b/example/example-modules.py
@ -28,3 +28,16 @@ print(b.get_a2())
 print(b.a2)

 print(OD([(1, 'a'), (2, 'b')]))
+
+from example import ConstructorStats
+
+cstats = [ConstructorStats.get(A), ConstructorStats.get(B)]
+print("Instances not destroyed:", [x.alive() for x in cstats])
+b = None
+print("Instances not destroyed:", [x.alive() for x in cstats])
+print("Constructor values:", [x.values() for x in cstats])
+print("Default constructions:", [x.default_constructions for x in cstats])
+print("Copy constructions:", [x.copy_constructions for x in cstats])
+#print("Move constructions:", [x.move_constructions >= 0 for x in cstats]) # Don't invoke any
+print("Copy assignments:", [x.copy_assignments for x in cstats])
+print("Move assignments:", [x.move_assignments for x in cstats])
--- a/example/example-modules.ref
+++ b/example/example-modules.ref
@ -1,22 +1,31 @@
 example
 example.submodule
 submodule_func()
-A constructor
-A constructor
-B constructor
+### A @ 0x21a5bc0 created 1
+### A @ 0x21a5bc4 created 2
+### B @ 0x21a5bc0 created via default constructor
 A[1]
 A[1]
 A[2]
 A[2]
-A constructor
-A destructor
-A constructor
-A destructor
+### A @ 0x20f93b0 created 42
+### A @ 0x21a5bc0 assigned via copy assignment
+### A @ 0x20f93b0 destroyed
+### A @ 0x20f93d0 created 43
+### A @ 0x21a5bc4 assigned via copy assignment
+### A @ 0x20f93d0 destroyed
 A[42]
 A[42]
 A[43]
 A[43]
 OrderedDict([(1, 'a'), (2, 'b')])
-B destructor
-A destructor
-A destructor
+Instances not destroyed: [2, 1]
+### B @ 0x21a5bc0 destroyed
+### A @ 0x21a5bc4 destroyed
+### A @ 0x21a5bc0 destroyed
+Instances not destroyed: [0, 0]
+Constructor values: [['1', '2', '42', '43'], []]
+Default constructions: [0, 1]
+Copy constructions: [0, 0]
+Copy assignments: [2, 0]
+Move assignments: [0, 0]
--- a/example/example-opaque-types.py
+++ b/example/example-opaque-types.py
@ -34,6 +34,8 @@ print_opaque_list(cvp.stringList)

 print_void_ptr(return_void_ptr())
 print_void_ptr(ExampleMandA())  # Should also work for other C++ types
+from example import ConstructorStats
+print("ExampleMandA still alive:", ConstructorStats.get(ExampleMandA).alive())

 try:
    print_void_ptr([1, 2, 3])  # This should not work
--- a/example/example-opaque-types.ref
+++ b/example/example-opaque-types.ref
@ -6,13 +6,14 @@ Opaque list: [Element 1]
 Opaque list: []
 Opaque list: [Element 1, Element 3]
 Got void ptr : 0x1234
-Called ExampleMandA default constructor..
-Got void ptr : 0x7f9ba0f3c430
-Called ExampleMandA destructor (0)
+### ExampleMandA @ 0x2ac5370 created via default constructor
+Got void ptr : 0x2ac5370
+### ExampleMandA @ 0x2ac5370 destroyed
+ExampleMandA still alive: 0
 Caught expected exception: Incompatible function arguments. The following argument types are supported:
    1. (arg0: capsule) -> None
    Invoked with: [1, 2, 3]
 None
 Got null str : 0x0
-<example.StringList object at 0x10d3277a0>
+<example.StringList object at 0x7f7ecde6fc00>
 Opaque list: [some value]
--- a/example/example-operator-overloading.cpp
+++ b/example/example-operator-overloading.cpp
@ -8,27 +8,28 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/operators.h>

 class Vector2 {
 public:
-    Vector2(float x, float y) : x(x), y(y) { std::cout << "Value constructor" << std::endl; }
-    Vector2(const Vector2 &v) : x(v.x), y(v.y) { std::cout << "Copy constructor" << std::endl; }
-    Vector2(Vector2 &&v) : x(v.x), y(v.y) { std::cout << "Move constructor" << std::endl; v.x = v.y = 0; }
-    ~Vector2() { std::cout << "Destructor." << std::endl; }
+    Vector2(float x, float y) : x(x), y(y) { print_created(this, toString()); }
+    Vector2(const Vector2 &v) : x(v.x), y(v.y) { print_copy_created(this); }
+    Vector2(Vector2 &&v) : x(v.x), y(v.y) { print_move_created(this); v.x = v.y = 0; }
+    ~Vector2() { print_destroyed(this); }

    std::string toString() const {
        return "[" + std::to_string(x) + ", " + std::to_string(y) + "]";
    }

    void operator=(const Vector2 &v) {
-        cout << "Assignment operator" << endl;
+        print_copy_assigned(this);
        x = v.x;
        y = v.y;
    }

    void operator=(Vector2 &&v) {
-        cout << "Move assignment operator" << endl;
+        print_move_assigned(this);
        x = v.x; y = v.y; v.x = v.y = 0;
    }

@ -51,7 +52,6 @@ private:
    float x, y;
 };

-
 void init_ex_operator_overloading(py::module &m) {
    py::class_<Vector2>(m, "Vector2")
        .def(py::init<float, float>())
@ -69,7 +69,8 @@ void init_ex_operator_overloading(py::module &m) {
        .def(float() - py::self)
        .def(float() * py::self)
        .def(float() / py::self)
-        .def("__str__", &Vector2::toString);
+        .def("__str__", &Vector2::toString)
+        ;

    m.attr("Vector") = m.attr("Vector2");
 }
--- a/example/example-operator-overloading.py
+++ b/example/example-operator-overloading.py
@ -25,3 +25,17 @@ v1 += v2
 v1 *= 2

 print("(v1+v2)*2 = " + str(v1))
+
+from example import ConstructorStats
+cstats = ConstructorStats.get(Vector2)
+print("Instances not destroyed:", cstats.alive())
+v1 = None
+print("Instances not destroyed:", cstats.alive())
+v2 = None
+print("Instances not destroyed:", cstats.alive())
+print("Constructor values:", cstats.values())
+print("Default constructions:", cstats.default_constructions)
+print("Copy constructions:", cstats.copy_constructions)
+print("Move constructions:", cstats.move_constructions >= 10)
+print("Copy assignments:", cstats.copy_assignments)
+print("Move assignments:", cstats.move_assignments)
--- a/example/example-operator-overloading.ref
+++ b/example/example-operator-overloading.ref
@ -1,57 +1,66 @@
-Value constructor
-Value constructor
+### Vector2 @ 0x11f7830 created [1.000000, 2.000000]
+### Vector2 @ 0x11427c0 created [3.000000, -1.000000]
 v1    = [1.000000, 2.000000]
 v2    = [3.000000, -1.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144b8 created [4.000000, 1.000000]
+### Vector2 @ 0x11f7e90 created via move constructor
+### Vector2 @ 0x7ffef6b144b8 destroyed
+### Vector2 @ 0x11f7e90 destroyed
 v1+v2 = [4.000000, 1.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144b8 created [-2.000000, 3.000000]
+### Vector2 @ 0x11f7e90 created via move constructor
+### Vector2 @ 0x7ffef6b144b8 destroyed
+### Vector2 @ 0x11f7e90 destroyed
 v1-v2 = [-2.000000, 3.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144c8 created [-7.000000, -6.000000]
+### Vector2 @ 0x1115760 created via move constructor
+### Vector2 @ 0x7ffef6b144c8 destroyed
+### Vector2 @ 0x1115760 destroyed
 v1-8  = [-7.000000, -6.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144c8 created [9.000000, 10.000000]
+### Vector2 @ 0x1115760 created via move constructor
+### Vector2 @ 0x7ffef6b144c8 destroyed
+### Vector2 @ 0x1115760 destroyed
 v1+8  = [9.000000, 10.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144b8 created [8.000000, 16.000000]
+### Vector2 @ 0x1115760 created via move constructor
+### Vector2 @ 0x7ffef6b144b8 destroyed
+### Vector2 @ 0x1115760 destroyed
 v1*8  = [8.000000, 16.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144a8 created [0.125000, 0.250000]
+### Vector2 @ 0x112f150 created via move constructor
+### Vector2 @ 0x7ffef6b144a8 destroyed
+### Vector2 @ 0x112f150 destroyed
 v1/8  = [0.125000, 0.250000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144f8 created [7.000000, 6.000000]
+### Vector2 @ 0x112f1b0 created via move constructor
+### Vector2 @ 0x7ffef6b144f8 destroyed
+### Vector2 @ 0x112f1b0 destroyed
 8-v1  = [7.000000, 6.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144f8 created [9.000000, 10.000000]
+### Vector2 @ 0x112f1b0 created via move constructor
+### Vector2 @ 0x7ffef6b144f8 destroyed
+### Vector2 @ 0x112f1b0 destroyed
 8+v1  = [9.000000, 10.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144e8 created [8.000000, 16.000000]
+### Vector2 @ 0x112f230 created via move constructor
+### Vector2 @ 0x7ffef6b144e8 destroyed
+### Vector2 @ 0x112f230 destroyed
 8*v1  = [8.000000, 16.000000]
-Value constructor
-Move constructor
-Destructor.
-Destructor.
+### Vector2 @ 0x7ffef6b144d8 created [8.000000, 4.000000]
+### Vector2 @ 0x11fb360 created via move constructor
+### Vector2 @ 0x7ffef6b144d8 destroyed
+### Vector2 @ 0x11fb360 destroyed
 8/v1  = [8.000000, 4.000000]
 (v1+v2)*2 = [8.000000, 2.000000]
-Destructor.
-Destructor.
+Instances not destroyed: 2
+### Vector2 @ 0x11f7830 destroyed
+Instances not destroyed: 1
+### Vector2 @ 0x11427c0 destroyed
+Instances not destroyed: 0
+Constructor values: ['[1.000000, 2.000000]', '[3.000000, -1.000000]', '[4.000000, 1.000000]', '[-2.000000, 3.000000]', '[-7.000000, -6.000000]', '[9.000000, 10.000000]', '[8.000000, 16.000000]', '[0.125000, 0.250000]', '[7.000000, 6.000000]', '[9.000000, 10.000000]', '[8.000000, 16.000000]', '[8.000000, 4.000000]']
+Default constructions: 0
+Copy constructions: 0
+Move constructions: True
+Copy assignments: 0
+Move assignments: 0
--- a/example/example-python-types.cpp
+++ b/example/example-python-types.cpp
@ -9,6 +9,7 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/stl.h>

 #ifdef _WIN32
@ -19,11 +20,11 @@
 class ExamplePythonTypes {
 public:
    static ExamplePythonTypes *new_instance() {
-        return new ExamplePythonTypes();
-    }
-    ~ExamplePythonTypes() {
-        std::cout << "Destructing ExamplePythonTypes" << std::endl;
+        auto *ptr = new ExamplePythonTypes();
+        print_created(ptr, "via new_instance");
+        return ptr;
    }
+    ~ExamplePythonTypes() { print_destroyed(this); }

    /* Create and return a Python dictionary */
    py::dict get_dict() {
@ -168,5 +169,6 @@ void init_ex_python_types(py::module &m) {
        .def("throw_exception", &ExamplePythonTypes::throw_exception, "Throw an exception")
        .def_static("new_instance", &ExamplePythonTypes::new_instance, "Return an instance")
        .def_readwrite_static("value", &ExamplePythonTypes::value, "Static value member")
-        .def_readonly_static("value2", &ExamplePythonTypes::value2, "Static value member (readonly)");
+        .def_readonly_static("value2", &ExamplePythonTypes::value2, "Static value member (readonly)")
+        ;
 }
--- a/example/example-python-types.py
+++ b/example/example-python-types.py
@ -65,3 +65,10 @@ print("__name__(example.ExamplePythonTypes) = %s" % ExamplePythonTypes.__name__)
 print("__module__(example.ExamplePythonTypes) = %s" % ExamplePythonTypes.__module__)
 print("__name__(example.ExamplePythonTypes.get_set) = %s" % ExamplePythonTypes.get_set.__name__)
 print("__module__(example.ExamplePythonTypes.get_set) = %s" % ExamplePythonTypes.get_set.__module__)
+
+from example import ConstructorStats
+
+cstats = ConstructorStats.get(ExamplePythonTypes)
+print("Instances not destroyed:", cstats.alive())
+instance = None
+print("Instances not destroyed:", cstats.alive())
--- a/example/example-python-types.ref
+++ b/example/example-python-types.ref
@ -2,6 +2,7 @@
 5
 example.ExamplePythonTypes: No constructor defined!
 can't set attribute
+### ExamplePythonTypes @ 0x1045b80 created via new_instance
 key: key2, value=value2
 key: key, value=value
 key: key, value=value
@ -134,4 +135,6 @@ __name__(example.ExamplePythonTypes) = ExamplePythonTypes
 __module__(example.ExamplePythonTypes) = example
 __name__(example.ExamplePythonTypes.get_set) = get_set
 __module__(example.ExamplePythonTypes.get_set) = example
-Destructing ExamplePythonTypes
+Instances not destroyed: 1
+### ExamplePythonTypes @ 0x1045b80 destroyed
+Instances not destroyed: 0
--- a/example/example-sequences-and-iterators.cpp
+++ b/example/example-sequences-and-iterators.cpp
@ -9,51 +9,55 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/operators.h>
 #include <pybind11/stl.h>

 class Sequence {
 public:
    Sequence(size_t size) : m_size(size) {
-        std::cout << "Value constructor: Creating a sequence with " << m_size << " entries" << std::endl;
+        print_created(this, "of size", m_size);
        m_data = new float[size];
        memset(m_data, 0, sizeof(float) * size);
    }

    Sequence(const std::vector<float> &value) : m_size(value.size()) {
-        std::cout << "Value constructor: Creating a sequence with " << m_size << " entries" << std::endl;
+        print_created(this, "of size", m_size, "from std::vector");
        m_data = new float[m_size];
        memcpy(m_data, &value[0], sizeof(float) * m_size);
    }

    Sequence(const Sequence &s) : m_size(s.m_size) {
-        std::cout << "Copy constructor: Creating a sequence with " << m_size << " entries" << std::endl;
+        print_copy_created(this);
        m_data = new float[m_size];
        memcpy(m_data, s.m_data, sizeof(float)*m_size);
    }

    Sequence(Sequence &&s) : m_size(s.m_size), m_data(s.m_data) {
-        std::cout << "Move constructor: Creating a sequence with " << m_size << " entries" << std::endl;
+        print_move_created(this);
        s.m_size = 0;
        s.m_data = nullptr;
    }

    ~Sequence() {
-        std::cout << "Freeing a sequence with " << m_size << " entries" << std::endl;
+        print_destroyed(this);
        delete[] m_data;
    }

    Sequence &operator=(const Sequence &s) {
-        std::cout << "Assignment operator: Creating a sequence with " << s.m_size << " entries" << std::endl;
+        if (&s != this) {
            delete[] m_data;
            m_size = s.m_size;
            m_data = new float[m_size];
            memcpy(m_data, s.m_data, sizeof(float)*m_size);
+        }
+
+        print_copy_assigned(this);
+
        return *this;
    }

    Sequence &operator=(Sequence &&s) {
-        std::cout << "Move assignment operator: Creating a sequence with " << s.m_size << " entries" << std::endl;
        if (&s != this) {
            delete[] m_data;
            m_size = s.m_size;
@ -61,6 +65,9 @@ public:
            s.m_size = 0;
            s.m_data = nullptr;
        }
+
+        print_move_assigned(this);
+
        return *this;
    }

--- a/example/example-sequences-and-iterators.py
+++ b/example/example-sequences-and-iterators.py
@ -28,3 +28,19 @@ rev[0::2] = Sequence([2.0, 2.0, 2.0])
 for i in rev:
    print(i, end=' ')
 print('')
+
+from example import ConstructorStats
+cstats = ConstructorStats.get(Sequence)
+print("Instances not destroyed:", cstats.alive())
+s = None
+print("Instances not destroyed:", cstats.alive())
+rev = None
+print("Instances not destroyed:", cstats.alive())
+rev2 = None
+print("Instances not destroyed:", cstats.alive())
+print("Constructor values:", cstats.values())
+print("Default constructions:", cstats.default_constructions)
+print("Copy constructions:", cstats.copy_constructions)
+print("Move constructions:", cstats.move_constructions >= 1)
+print("Copy assignments:", cstats.copy_assignments)
+print("Move assignments:", cstats.move_assignments)
--- a/example/example-sequences-and-iterators.ref
+++ b/example/example-sequences-and-iterators.ref
@ -1,21 +1,31 @@
-Value constructor: Creating a sequence with 5 entries
-s = <example.Sequence object at 0x10c786c70>
+### Sequence @ 0x1535b00 created of size 5
+s = <example.Sequence object at 0x7efc73cfa4e0>
 len(s) = 5
 s[0], s[3] = 0.000000 0.000000
 12.34 in s: False
 12.34 in s: True
 s[0], s[3] = 12.340000 56.779999
-Value constructor: Creating a sequence with 5 entries
-Move constructor: Creating a sequence with 5 entries
-Freeing a sequence with 0 entries
-Value constructor: Creating a sequence with 5 entries
+### Sequence @ 0x7fff22a45068 created of size 5
+### Sequence @ 0x1538b90 created via move constructor
+### Sequence @ 0x7fff22a45068 destroyed
+### Sequence @ 0x1538bf0 created of size 5
 rev[0], rev[1], rev[2], rev[3], rev[4] = 0.000000 56.779999 0.000000 0.000000 12.340000
-0.0 56.7799987793 0.0 0.0 12.3400001526 
-0.0 56.7799987793 0.0 0.0 12.3400001526 
+0.0 56.779998779296875 0.0 0.0 12.34000015258789 
+0.0 56.779998779296875 0.0 0.0 12.34000015258789 
 True
-Value constructor: Creating a sequence with 3 entries
-Freeing a sequence with 3 entries
-2.0 56.7799987793 2.0 0.0 2.0 
-Freeing a sequence with 5 entries
-Freeing a sequence with 5 entries
-Freeing a sequence with 5 entries
+### Sequence @ 0x153c4b0 created of size 3  from std::vector
+### Sequence @ 0x153c4b0 destroyed
+2.0 56.779998779296875 2.0 0.0 2.0 
+Instances not destroyed: 3
+### Sequence @ 0x1535b00 destroyed
+Instances not destroyed: 2
+### Sequence @ 0x1538b90 destroyed
+Instances not destroyed: 1
+### Sequence @ 0x1538bf0 destroyed
+Instances not destroyed: 0
+Constructor values: ['of size', '5', 'of size', '5', 'of size', '5', 'of size', '3', 'from std::vector']
+Default constructions: 0
+Copy constructions: 0
+Move constructions: True
+Copy assignments: 0
+Move assignments: 0
--- a/example/example-smart-ptr.cpp
+++ b/example/example-smart-ptr.cpp
@ -15,7 +15,7 @@
 class MyObject1 : public Object {
 public:
    MyObject1(int value) : value(value) {
-        std::cout << toString() << " constructor" << std::endl;
+        print_created(this, toString());
    }

    std::string toString() const {
@ -24,7 +24,7 @@ public:

 protected:
    virtual ~MyObject1() {
-        std::cout << toString() << " destructor" << std::endl;
+        print_destroyed(this);
    }

 private:
@ -35,7 +35,7 @@ private:
 class MyObject2 {
 public:
    MyObject2(int value) : value(value) {
-        std::cout << toString() << " constructor" << std::endl;
+        print_created(this, toString());
    }

    std::string toString() const {
@ -43,7 +43,7 @@ public:
    }

    virtual ~MyObject2() {
-        std::cout << toString() << " destructor" << std::endl;
+        print_destroyed(this);
    }

 private:
@ -54,7 +54,7 @@ private:
 class MyObject3 : public std::enable_shared_from_this<MyObject3> {
 public:
    MyObject3(int value) : value(value) {
-        std::cout << toString() << " constructor" << std::endl;
+        print_created(this, toString());
    }

    std::string toString() const {
@ -62,7 +62,7 @@ public:
    }

    virtual ~MyObject3() {
-        std::cout << toString() << " destructor" << std::endl;
+        print_destroyed(this);
    }

 private:
@ -144,4 +144,7 @@ void init_ex_smart_ptr(py::module &m) {
    m.def("print_myobject3_4", &print_myobject3_4);

    py::implicitly_convertible<py::int_, MyObject1>();
+
+    // Expose constructor stats for the ref type
+    m.def("cstats_ref", &ConstructorStats::get<ref_tag>);
 }
--- a/example/example-smart-ptr.py
+++ b/example/example-smart-ptr.py
@ -68,3 +68,18 @@ for o in [MyObject3(9), make_myobject3_1(), make_myobject3_2()]:
    print_myobject3_2(o)
    print_myobject3_3(o)
    print_myobject3_4(o)
+
+from example import ConstructorStats, cstats_ref, Object
+
+cstats = [ConstructorStats.get(Object), ConstructorStats.get(MyObject1),
+        ConstructorStats.get(MyObject2), ConstructorStats.get(MyObject3),
+        cstats_ref()]
+print("Instances not destroyed:", [x.alive() for x in cstats])
+o = None
+print("Instances not destroyed:", [x.alive() for x in cstats])
+print("Object value constructions:", [x.values() for x in cstats])
+print("Default constructions:", [x.default_constructions for x in cstats])
+print("Copy constructions:", [x.copy_constructions for x in cstats])
+#print("Move constructions:", [x.move_constructions >= 0 for x in cstats]) # Doesn't invoke any
+print("Copy assignments:", [x.copy_assignments for x in cstats])
+print("Move assignments:", [x.move_assignments for x in cstats])
--- a/example/example-smart-ptr.ref
+++ b/example/example-smart-ptr.ref
@ -1,243 +1,270 @@
-MyObject1[1] constructor
-Initialized ref from pointer 0x1347ba0
-MyObject1[2] constructor
-Initialized ref from pointer 0x12b9270
-Initialized ref from ref 0x12b9270
-Destructing ref 0x12b9270
-MyObject1[3] constructor
-Initialized ref from pointer 0x12a2a90
-MyObject1[1]
-Created empty ref
-Assigning ref 0x1347ba0
-Initialized ref from ref 0x1347ba0
-MyObject1[1]
-Destructing ref 0x1347ba0
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[1]
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[1]
-Destructing ref 0x1347ba0
-MyObject1[2]
-Created empty ref
-Assigning ref 0x12b9270
-Initialized ref from ref 0x12b9270
-MyObject1[2]
-Destructing ref 0x12b9270
-Destructing ref 0x12b9270
-Created empty ref
-Assigning ref 0x12b9270
-MyObject1[2]
-Destructing ref 0x12b9270
-Created empty ref
-Assigning ref 0x12b9270
-MyObject1[2]
-Destructing ref 0x12b9270
-MyObject1[3]
-Created empty ref
-Assigning ref 0x12a2a90
-Initialized ref from ref 0x12a2a90
-MyObject1[3]
-Destructing ref 0x12a2a90
-Destructing ref 0x12a2a90
-Created empty ref
-Assigning ref 0x12a2a90
-MyObject1[3]
-Destructing ref 0x12a2a90
-Created empty ref
-Assigning ref 0x12a2a90
-MyObject1[3]
-Destructing ref 0x12a2a90
-Destructing ref 0x12b9270
-MyObject1[2] destructor
-Destructing ref 0x1347ba0
-MyObject1[1] destructor
-MyObject1[4] constructor
-Initialized ref from pointer 0x1347ba0
-MyObject1[5] constructor
-Initialized ref from pointer 0x1299190
-Initialized ref from ref 0x1299190
-Destructing ref 0x1299190
-MyObject1[6] constructor
-Initialized ref from pointer 0x133e2f0
-Destructing ref 0x12a2a90
-MyObject1[3] destructor
-MyObject1[4]
-Created empty ref
-Assigning ref 0x1347ba0
-Initialized ref from ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-MyObject1[4]
-Created empty ref
-Assigning ref 0x1347ba0
-Initialized ref from ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-Created empty ref
-Assigning ref 0x1347ba0
-MyObject1[4]
-Destructing ref 0x1347ba0
-MyObject1[5]
-Created empty ref
-Assigning ref 0x1299190
-Initialized ref from ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-Destructing ref 0x1299190
-Created empty ref
-Assigning ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-Created empty ref
-Assigning ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-MyObject1[5]
-Created empty ref
-Assigning ref 0x1299190
-Initialized ref from ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-Destructing ref 0x1299190
-Created empty ref
-Assigning ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-Created empty ref
-Assigning ref 0x1299190
-MyObject1[5]
-Destructing ref 0x1299190
-MyObject1[6]
-Created empty ref
-Assigning ref 0x133e2f0
-Initialized ref from ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-Destructing ref 0x133e2f0
-Created empty ref
-Assigning ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-Created empty ref
-Assigning ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-MyObject1[6]
-Created empty ref
-Assigning ref 0x133e2f0
-Initialized ref from ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-Destructing ref 0x133e2f0
-Created empty ref
-Assigning ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-Created empty ref
-Assigning ref 0x133e2f0
-MyObject1[6]
-Destructing ref 0x133e2f0
-MyObject1[7] constructor
-Initialized ref from pointer 0x133f3a0
-MyObject1[7]
-Destructing ref 0x133f3a0
-MyObject1[7] destructor
-Created empty ref
-MyObject1[7] constructor
-Initialized ref from pointer 0x12a2a90
-Assigning ref 0x12a2a90
-Initialized ref from ref 0x12a2a90
-MyObject1[7]
-Destructing ref 0x12a2a90
-Destructing ref 0x12a2a90
-Destructing ref 0x12a2a90
-MyObject1[7] destructor
-Created empty ref
-MyObject1[7] constructor
-Initialized ref from pointer 0x133f3a0
-Assigning ref 0x133f3a0
-MyObject1[7]
-Destructing ref 0x133f3a0
-Destructing ref 0x133f3a0
-MyObject1[7] destructor
-Created empty ref
-MyObject1[7] constructor
-Initialized ref from pointer 0x12a2a90
-Assigning ref 0x12a2a90
-MyObject1[7]
-Destructing ref 0x12a2a90
-Destructing ref 0x12a2a90
-MyObject1[7] destructor
-Destructing ref 0x133e2f0
-MyObject1[6] destructor
-Destructing ref 0x1299190
-MyObject1[5] destructor
-Destructing ref 0x1347ba0
-MyObject1[4] destructor
-MyObject2[8] constructor
-MyObject2[6] constructor
-MyObject2[7] constructor
-MyObject2[8]
-MyObject2[8]
-MyObject2[8]
-MyObject2[8]
-MyObject2[6]
-MyObject2[6]
-MyObject2[6]
-MyObject2[6]
-MyObject2[7]
-MyObject2[7]
-MyObject2[7]
-MyObject2[7]
-MyObject2[6] destructor
-MyObject2[8] destructor
-MyObject3[9] constructor
-MyObject3[8] constructor
-MyObject3[9] constructor
-MyObject2[7] destructor
-MyObject3[9]
-MyObject3[9]
-MyObject3[9]
-MyObject3[9]
-MyObject3[8]
-MyObject3[8]
-MyObject3[8]
-MyObject3[8]
-MyObject3[9]
-MyObject3[9]
-MyObject3[9]
-MyObject3[9]
-MyObject3[8] destructor
-MyObject3[9] destructor
+### Object @ 0xdeffd0 created via default constructor
+### MyObject1 @ 0xdeffd0 created MyObject1[1]
+### ref<MyObject1> @ 0x7f6a2e03c4a8 created from pointer 0xdeffd0
+### Object @ 0xe43f50 created via default constructor
+### MyObject1 @ 0xe43f50 created MyObject1[2]
+### ref<Object> @ 0x7fff136845d0 created from pointer 0xe43f50
+### ref<MyObject1> @ 0x7f6a2c32aad8 created via copy constructor with pointer 0xe43f50
+### ref<Object> @ 0x7fff136845d0 destroyed
+### Object @ 0xee8cf0 created via default constructor
+### MyObject1 @ 0xee8cf0 created MyObject1[3]
+### ref<MyObject1> @ 0x7f6a2c32ab08 created from pointer 0xee8cf0
 Reference count = 1
+MyObject1[1]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xdeffd0
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xdeffd0
+MyObject1[1]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xdeffd0
+MyObject1[1]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xdeffd0
+MyObject1[1]
+### ref<Object> @ 0x7fff136845c8 destroyed
 Reference count = 1
+MyObject1[2]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xe43f50
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xe43f50
+MyObject1[2]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xe43f50
+MyObject1[2]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xe43f50
+MyObject1[2]
+### ref<Object> @ 0x7fff136845c8 destroyed
 Reference count = 1
-<example.MyObject1 object at 0x7f830b500e68>
-<example.MyObject1 object at 0x7f830b4fc688>
-<example.MyObject1 object at 0x7f830b4fc5a8>
+MyObject1[3]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8cf0
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xee8cf0
+MyObject1[3]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8cf0
+MyObject1[3]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8cf0
+MyObject1[3]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### MyObject1 @ 0xe43f50 destroyed
+### Object @ 0xe43f50 destroyed
+### ref<MyObject1> @ 0x7f6a2c32aad8 destroyed
+### MyObject1 @ 0xdeffd0 destroyed
+### Object @ 0xdeffd0 destroyed
+### ref<MyObject1> @ 0x7f6a2e03c4a8 destroyed
+### Object @ 0xee8310 created via default constructor
+### MyObject1 @ 0xee8310 created MyObject1[4]
+### ref<MyObject1> @ 0x7f6a2e03c4a8 created from pointer 0xee8310
+### Object @ 0xee8470 created via default constructor
+### MyObject1 @ 0xee8470 created MyObject1[5]
+### ref<MyObject1> @ 0x7fff136845d0 created from pointer 0xee8470
+### ref<MyObject1> @ 0x7f6a2c32aad8 created via copy constructor with pointer 0xee8470
+### ref<MyObject1> @ 0x7fff136845d0 destroyed
+### Object @ 0xee95a0 created via default constructor
+### MyObject1 @ 0xee95a0 created MyObject1[6]
+### ref<MyObject1> @ 0x7f6a2c32ab38 created from pointer 0xee95a0
+### MyObject1 @ 0xee8cf0 destroyed
+### Object @ 0xee8cf0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab08 destroyed
+<example.MyObject1 object at 0x7f6a2e03c480>
+MyObject1[4]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xee8310
+MyObject1[4]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+MyObject1[4]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+MyObject1[4]
+### ref<Object> @ 0x7fff136845c8 destroyed
+MyObject1[4]
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+### ref<MyObject1> @ 0x7fff136845a8 created via copy constructor with pointer 0xee8310
+MyObject1[4]
+### ref<MyObject1> @ 0x7fff136845a8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+MyObject1[4]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8310
+MyObject1[4]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+<example.MyObject1 object at 0x7f6a2c32aab0>
+MyObject1[5]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xee8470
+MyObject1[5]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+MyObject1[5]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+MyObject1[5]
+### ref<Object> @ 0x7fff136845c8 destroyed
+MyObject1[5]
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+### ref<MyObject1> @ 0x7fff136845a8 created via copy constructor with pointer 0xee8470
+MyObject1[5]
+### ref<MyObject1> @ 0x7fff136845a8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+MyObject1[5]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee8470
+MyObject1[5]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+<example.MyObject1 object at 0x7f6a2c32ab10>
+MyObject1[6]
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+### ref<Object> @ 0x7fff136845a8 created via copy constructor with pointer 0xee95a0
+MyObject1[6]
+### ref<Object> @ 0x7fff136845a8 destroyed
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+MyObject1[6]
+### ref<Object> @ 0x7fff136845c8 destroyed
+### ref<Object> @ 0x7fff136845c8 created via default constructor
+### ref<Object> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+MyObject1[6]
+### ref<Object> @ 0x7fff136845c8 destroyed
+MyObject1[6]
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+### ref<MyObject1> @ 0x7fff136845a8 created via copy constructor with pointer 0xee95a0
+MyObject1[6]
+### ref<MyObject1> @ 0x7fff136845a8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+MyObject1[6]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee95a0
+MyObject1[6]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
 7
-<example.MyObject2 object at 0x7f830b50b330>
-<example.MyObject2 object at 0x7f830b50bdb0>
-<example.MyObject2 object at 0x7f83098f6330>
-<example.MyObject3 object at 0x7f830b50b330>
-<example.MyObject3 object at 0x7f830b50bdb0>
-<example.MyObject3 object at 0x7f83098f6370>
-MyObject3[9] destructor
+### Object @ 0xee97f0 created via default constructor
+### MyObject1 @ 0xee97f0 created MyObject1[7]
+### ref<MyObject1> @ 0x7f6a2c32ab08 created from pointer 0xee97f0
+MyObject1[7]
+### MyObject1 @ 0xee97f0 destroyed
+### Object @ 0xee97f0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab08 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### Object @ 0xee99e0 created via default constructor
+### MyObject1 @ 0xee99e0 created MyObject1[7]
+### ref<MyObject1> @ 0x7f6a2c32ab08 created from pointer 0xee99e0
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee99e0
+### ref<MyObject1> @ 0x7fff136845a8 created via copy constructor with pointer 0xee99e0
+MyObject1[7]
+### ref<MyObject1> @ 0x7fff136845a8 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### MyObject1 @ 0xee99e0 destroyed
+### Object @ 0xee99e0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab08 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### Object @ 0xee97f0 created via default constructor
+### MyObject1 @ 0xee97f0 created MyObject1[7]
+### ref<MyObject1> @ 0x7f6a2c32ab08 created from pointer 0xee97f0
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee97f0
+MyObject1[7]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### MyObject1 @ 0xee97f0 destroyed
+### Object @ 0xee97f0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab08 destroyed
+### ref<MyObject1> @ 0x7fff136845c8 created via default constructor
+### Object @ 0xee99e0 created via default constructor
+### MyObject1 @ 0xee99e0 created MyObject1[7]
+### ref<MyObject1> @ 0x7f6a2c32ab08 created from pointer 0xee99e0
+### ref<MyObject1> @ 0x7fff136845c8 assigned via copy assignment pointer 0xee99e0
+MyObject1[7]
+### ref<MyObject1> @ 0x7fff136845c8 destroyed
+### MyObject1 @ 0xee99e0 destroyed
+### Object @ 0xee99e0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab08 destroyed
+### MyObject1 @ 0xee95a0 destroyed
+### Object @ 0xee95a0 destroyed
+### ref<MyObject1> @ 0x7f6a2c32ab38 destroyed
+### MyObject1 @ 0xee8470 destroyed
+### Object @ 0xee8470 destroyed
+### ref<MyObject1> @ 0x7f6a2c32aad8 destroyed
+### MyObject1 @ 0xee8310 destroyed
+### Object @ 0xee8310 destroyed
+### ref<MyObject1> @ 0x7f6a2e03c4a8 destroyed
+### MyObject2 @ 0xe43f50 created MyObject2[8]
+### MyObject2 @ 0xee95a0 created MyObject2[6]
+### MyObject2 @ 0xee95d0 created MyObject2[7]
+<example.MyObject2 object at 0x7f6a2dfc8768>
+MyObject2[8]
+MyObject2[8]
+MyObject2[8]
+MyObject2[8]
+<example.MyObject2 object at 0x7f6a2dfc86c0>
+MyObject2[6]
+MyObject2[6]
+MyObject2[6]
+MyObject2[6]
+<example.MyObject2 object at 0x7f6a2c32d030>
+MyObject2[7]
+MyObject2[7]
+MyObject2[7]
+MyObject2[7]
+### MyObject2 @ 0xee95a0 destroyed
+### MyObject2 @ 0xe43f50 destroyed
+### MyObject3 @ 0xee9ac0 created MyObject3[9]
+### MyObject3 @ 0xe43f90 created MyObject3[8]
+### MyObject3 @ 0xeea7d0 created MyObject3[9]
+### MyObject2 @ 0xee95d0 destroyed
+<example.MyObject3 object at 0x7f6a2dfc8768>
+MyObject3[9]
+MyObject3[9]
+MyObject3[9]
+MyObject3[9]
+<example.MyObject3 object at 0x7f6a2dfc86c0>
+MyObject3[8]
+MyObject3[8]
+MyObject3[8]
+MyObject3[8]
+<example.MyObject3 object at 0x7f6a2c32d068>
+MyObject3[9]
+MyObject3[9]
+MyObject3[9]
+MyObject3[9]
+### MyObject3 @ 0xe43f90 destroyed
+### MyObject3 @ 0xee9ac0 destroyed
+Instances not destroyed: [0, 0, 0, 1, 0]
+### MyObject3 @ 0xeea7d0 destroyed
+Instances not destroyed: [0, 0, 0, 0, 0]
+Object value constructions: [[], ['MyObject1[1]', 'MyObject1[2]', 'MyObject1[3]', 'MyObject1[4]', 'MyObject1[5]', 'MyObject1[6]', 'MyObject1[7]', 'MyObject1[7]', 'MyObject1[7]', 'MyObject1[7]'], ['MyObject2[8]', 'MyObject2[6]', 'MyObject2[7]'], ['MyObject3[9]', 'MyObject3[8]', 'MyObject3[9]'], ['from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer', 'from pointer']]
+Default constructions: [10, 0, 0, 0, 30]
+Copy constructions: [0, 0, 0, 0, 12]
+Copy assignments: [0, 0, 0, 0, 30]
+Move assignments: [0, 0, 0, 0, 0]
--- a/example/example-virtual-functions.cpp
+++ b/example/example-virtual-functions.cpp
@ -8,18 +8,16 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/functional.h>

 /* This is an example class that we'll want to be able to extend from Python */
 class ExampleVirt  {
 public:
-    ExampleVirt(int state) : state(state) {
-        cout << "Constructing ExampleVirt.." << endl;
-    }
-
-    ~ExampleVirt() {
-        cout << "Destructing ExampleVirt.." << endl;
-    }
+    ExampleVirt(int state) : state(state) { print_created(this, state); }
+    ExampleVirt(const ExampleVirt &e) : state(e.state) { print_copy_created(this); }
+    ExampleVirt(ExampleVirt &&e) : state(e.state) { print_move_created(this); e.state = 0; }
+    ~ExampleVirt() { print_destroyed(this); }

    virtual int run(int value) {
        std::cout << "Original implementation of ExampleVirt::run(state=" << state
@ -71,8 +69,8 @@ public:

 class NonCopyable {
 public:
-    NonCopyable(int a, int b) : value{new int(a*b)} {}
-    NonCopyable(NonCopyable &&) = default;
+    NonCopyable(int a, int b) : value{new int(a*b)} { print_created(this, a, b); }
+    NonCopyable(NonCopyable &&o) { value = std::move(o.value); print_move_created(this); }
    NonCopyable(const NonCopyable &) = delete;
    NonCopyable() = delete;
    void operator=(const NonCopyable &) = delete;
@ -80,7 +78,7 @@ public:
    std::string get_value() const {
        if (value) return std::to_string(*value); else return "(null)";
    }
-    ~NonCopyable() { std::cout << "NonCopyable destructor @ " << this << "; value = " << get_value() << std::endl; }
+    ~NonCopyable() { print_destroyed(this); }

 private:
    std::unique_ptr<int> value;
@ -90,11 +88,11 @@ private:
 // when it is not referenced elsewhere, but copied if it is still referenced.
 class Movable {
 public:
-    Movable(int a, int b) : value{a+b} {}
-    Movable(const Movable &m) { value = m.value; std::cout << "Movable @ " << this << " copy constructor" << std::endl; }
-    Movable(Movable &&m) { value = std::move(m.value); std::cout << "Movable @ " << this << " move constructor" << std::endl; }
+    Movable(int a, int b) : value{a+b} { print_created(this, a, b); }
+    Movable(const Movable &m) { value = m.value; print_copy_created(this); }
+    Movable(Movable &&m) { value = std::move(m.value); print_move_created(this); }
    int get_value() const { return value; }
-    ~Movable() { std::cout << "Movable destructor @ " << this << "; value = " << get_value() << std::endl; }
+    ~Movable() { print_destroyed(this); }
 private:
    int value;
 };
@ -305,5 +303,6 @@ void init_ex_virtual_functions(py::module &m) {
    m.def("runExampleVirtBool", &runExampleVirtBool);
    m.def("runExampleVirtVirtual", &runExampleVirtVirtual);

+    m.def("cstats_debug", &ConstructorStats::get<ExampleVirt>);
    initialize_inherited_virtuals(m);
 }
--- a/example/example-virtual-functions.py
+++ b/example/example-virtual-functions.py
@ -37,8 +37,6 @@ print(runExampleVirt(ex12p, 20))
 print(runExampleVirtBool(ex12p))
 runExampleVirtVirtual(ex12p)

-sys.stdout.flush()
-
 class VI_AR(A_Repeat):
    def unlucky_number(self):
        return 99
@ -122,3 +120,16 @@ try:
 except RuntimeError as e:
    # Don't print the exception message here because it differs under debug/non-debug mode
    print("Caught expected exception")
+
+from example import ConstructorStats
+del ex12
+del ex12p
+del obj
+del ncv1
+del ncv2
+cstats = [ConstructorStats.get(ExampleVirt), ConstructorStats.get(NonCopyable), ConstructorStats.get(Movable)]
+print("Instances not destroyed:", [x.alive() for x in cstats])
+print("Constructor values:", [x.values() for x in cstats])
+print("Copy constructions:", [x.copy_constructions for x in cstats])
+print("Move constructions:", [cstats[i].move_constructions >= 1 for i in range(1, len(cstats))])
+
--- a/example/example-virtual-functions.ref
+++ b/example/example-virtual-functions.ref
@ -1,8 +1,8 @@
-Constructing ExampleVirt..
+### ExampleVirt @ 0x2073a90 created 10
 Original implementation of ExampleVirt::run(state=10, value=20)
 30
 Caught expected exception: Tried to call pure virtual function "ExampleVirt::pure_virtual"
-Constructing ExampleVirt..
+### ExampleVirt @ 0x2076a00 created 11
 ExtendedExampleVirt::run(20), calling parent..
 Original implementation of ExampleVirt::run(state=11, value=21)
 32
@ -78,20 +78,29 @@ VI_DT says: quack quack quack
 Unlucky = 1234
 Lucky = -4.25
 2^2 * 3^2 =
-NonCopyable destructor @ 0x1a6c3f0; value = (null)
+### NonCopyable @ 0x207df10 created 4 9
+### NonCopyable @ 0x7ffcfe866228 created via move constructor
+### NonCopyable @ 0x207df10 destroyed
 36
-NonCopyable destructor @ 0x7ffc6d1fbaa8; value = 36
+### NonCopyable @ 0x7ffcfe866228 destroyed
 4 + 5 =
-Movable @ 0x7ffc6d1fbacc copy constructor
+### Movable @ 0x207e230 created 4 5
+### Movable @ 0x7ffcfe86624c created via copy constructor
 9
-Movable destructor @ 0x7ffc6d1fbacc; value = 9
+### Movable @ 0x7ffcfe86624c destroyed
 7 + 7 =
-Movable @ 0x7ffc6d1fbacc move constructor
-Movable destructor @ 0x1a6c4d0; value = 14
+### Movable @ 0x20259e0 created 7 7
+### Movable @ 0x7ffcfe86624c created via move constructor
+### Movable @ 0x20259e0 destroyed
 14
-Movable destructor @ 0x7ffc6d1fbacc; value = 14
+### Movable @ 0x7ffcfe86624c destroyed
+### NonCopyable @ 0x2025a00 created 9 9
 Caught expected exception
-NonCopyable destructor @ 0x29a64b0; value = 81
-Movable destructor @ 0x1a6c410; value = 9
-Destructing ExampleVirt..
-Destructing ExampleVirt..
+### ExampleVirt @ 0x2073a90 destroyed
+### ExampleVirt @ 0x2076a00 destroyed
+### Movable @ 0x207e230 destroyed
+### NonCopyable @ 0x2025a00 destroyed
+Instances not destroyed: [0, 0, 0]
+Constructor values: [['10', '11'], ['4', '9', '9', '9'], ['4', '5', '7', '7']]
+Copy constructions: [0, 0, 1]
+Move constructions: [True, True]
--- a/example/example.cpp
+++ b/example/example.cpp
@ -8,6 +8,7 @@
 */

 #include "example.h"
+#include "constructor-stats.h"

 void init_ex_methods_and_attributes(py::module &);
 void init_ex_python_types(py::module &);
@ -34,9 +35,24 @@ void init_issues(py::module &);
    void init_eigen(py::module &);
 #endif

+void bind_ConstructorStats(py::module &m) {
+    py::class_<ConstructorStats>(m, "ConstructorStats")
+        .def("alive", &ConstructorStats::alive)
+        .def("values", &ConstructorStats::values)
+        .def_readwrite("default_constructions", &ConstructorStats::default_constructions)
+        .def_readwrite("copy_assignments", &ConstructorStats::copy_assignments)
+        .def_readwrite("move_assignments", &ConstructorStats::move_assignments)
+        .def_readwrite("copy_constructions", &ConstructorStats::copy_constructions)
+        .def_readwrite("move_constructions", &ConstructorStats::move_constructions)
+        .def_static("get", (ConstructorStats &(*)(py::object)) &ConstructorStats::get, py::return_value_policy::reference_internal)
+        ;
+}
+
 PYBIND11_PLUGIN(example) {
    py::module m("example", "pybind example plugin");

+    bind_ConstructorStats(m);
+
    init_ex_methods_and_attributes(m);
    init_ex_python_types(m);
    init_ex_operator_overloading(m);
--- a/example/issues.cpp
+++ b/example/issues.cpp
@ -8,11 +8,18 @@
 */

 #include "example.h"
+#include "constructor-stats.h"
 #include <pybind11/stl.h>
 #include <pybind11/operators.h>

 PYBIND11_DECLARE_HOLDER_TYPE(T, std::shared_ptr<T>);

+#define TRACKERS(CLASS) CLASS() { print_default_created(this); } ~CLASS() { print_destroyed(this); }
+struct NestABase { int value = -2; TRACKERS(NestABase) };
+struct NestA : NestABase { int value = 3; NestA& operator+=(int i) { value += i; return *this; } TRACKERS(NestA) };
+struct NestB { NestA a; int value = 4; NestB& operator-=(int i) { value -= i; return *this; } TRACKERS(NestB) };
+struct NestC { NestB b; int value = 5; NestC& operator*=(int i) { value *= i; return *this; } TRACKERS(NestC) };
+
 void init_issues(py::module &m) {
    py::module m2 = m.def_submodule("issues");

@ -159,12 +166,6 @@ void init_issues(py::module &m) {
        ;

    // Issue #328: first member in a class can't be used in operators
-#define TRACKERS(CLASS) CLASS() { std::cout << #CLASS "@" << this << " constructor\n"; } \
-                        ~CLASS() { std::cout << #CLASS "@" << this << " destructor\n"; }
-    struct NestABase { int value = -2; TRACKERS(NestABase) };
-    struct NestA : NestABase { int value = 3; NestA& operator+=(int i) { value += i; return *this; } TRACKERS(NestA) };
-    struct NestB { NestA a; int value = 4; NestB& operator-=(int i) { value -= i; return *this; } TRACKERS(NestB) };
-    struct NestC { NestB b; int value = 5; NestC& operator*=(int i) { value *= i; return *this; } TRACKERS(NestC) };
    py::class_<NestABase>(m2, "NestABase").def(py::init<>()).def_readwrite("value", &NestABase::value);
    py::class_<NestA>(m2, "NestA").def(py::init<>()).def(py::self += int())
        .def("as_base", [](NestA &a) -> NestABase& { return (NestABase&) a; }, py::return_value_policy::reference_internal);
--- a/example/issues.ref
+++ b/example/issues.ref
@ -24,15 +24,15 @@ Failed as expected: Incompatible constructor arguments. The following argument t
    1. example.issues.StrIssue(arg0: int)
    2. example.issues.StrIssue()
    Invoked with: no, such, constructor
-NestABase@0x1152940 constructor
-NestA@0x1152940 constructor
-NestABase@0x11f9350 constructor
-NestA@0x11f9350 constructor
-NestB@0x11f9350 constructor
-NestABase@0x112d0d0 constructor
-NestA@0x112d0d0 constructor
-NestB@0x112d0d0 constructor
-NestC@0x112d0d0 constructor
+### NestABase @ 0x15eb630 created via default constructor
+### NestA @ 0x15eb630 created via default constructor
+### NestABase @ 0x1704000 created via default constructor
+### NestA @ 0x1704000 created via default constructor
+### NestB @ 0x1704000 created via default constructor
+### NestABase @ 0x1633110 created via default constructor
+### NestA @ 0x1633110 created via default constructor
+### NestB @ 0x1633110 created via default constructor
+### NestC @ 0x1633110 created via default constructor
 13
 103
 1003
@ -43,13 +43,13 @@ NestC@0x112d0d0 constructor
 42
 -2
 42
-NestC@0x112d0d0 destructor
-NestB@0x112d0d0 destructor
-NestA@0x112d0d0 destructor
-NestABase@0x112d0d0 destructor
+### NestC @ 0x1633110 destroyed
+### NestB @ 0x1633110 destroyed
+### NestA @ 0x1633110 destroyed
+### NestABase @ 0x1633110 destroyed
 42
-NestA@0x1152940 destructor
-NestABase@0x1152940 destructor
-NestB@0x11f9350 destructor
-NestA@0x11f9350 destructor
-NestABase@0x11f9350 destructor
+### NestA @ 0x15eb630 destroyed
+### NestABase @ 0x15eb630 destroyed
+### NestB @ 0x1704000 destroyed
+### NestA @ 0x1704000 destroyed
+### NestABase @ 0x1704000 destroyed
--- a/example/object.h
+++ b/example/object.h
@ -2,15 +2,16 @@
 #define __OBJECT_H

 #include <atomic>
+#include "constructor-stats.h"

 /// Reference counted object base class
 class Object {
 public:
    /// Default constructor
-    Object() { }
+    Object() { print_default_created(this); }

    /// Copy constructor
-    Object(const Object &) : m_refCount(0) {}
+    Object(const Object &) : m_refCount(0) { print_copy_created(this); }

 	/// Return the current reference count
 	int getRefCount() const { return m_refCount; };
@ -37,11 +38,17 @@ protected:
 	/** \brief Virtual protected deconstructor.
 	 * (Will only be called by \ref ref)
 	 */
-	virtual ~Object() { }
+	virtual ~Object() { print_destroyed(this); }
 private:
    mutable std::atomic<int> m_refCount { 0 };
 };

+// Tag class used to track constructions of ref objects.  When we track constructors, below, we
+// track and print out the actual class (e.g. ref<MyObject>), and *also* add a fake tracker for
+// ref_tag.  This lets us check that the total number of ref<Anything> constructors/destructors is
+// correct without having to check each individual ref<Whatever> type individually.
+class ref_tag {};
+
 /**
 * \brief Reference counting helper
 *
@ -55,37 +62,43 @@ private:
 template <typename T> class ref {
 public:
 	/// Create a nullptr reference
-    ref() : m_ptr(nullptr) { std::cout << "Created empty ref" << std::endl; }
+    ref() : m_ptr(nullptr) { print_default_created(this); track_default_created((ref_tag*) this); }

    /// Construct a reference from a pointer
 	ref(T *ptr) : m_ptr(ptr) {
-        std::cout << "Initialized ref from pointer " << ptr<< std::endl;
 	    if (m_ptr) ((Object *) m_ptr)->incRef();
+
+        print_created(this, "from pointer", m_ptr); track_created((ref_tag*) this, "from pointer");
+
 	}

 	/// Copy constructor
    ref(const ref &r) : m_ptr(r.m_ptr) {
-        std::cout << "Initialized ref from ref " << r.m_ptr << std::endl;
        if (m_ptr)
            ((Object *) m_ptr)->incRef();
+
+        print_copy_created(this, "with pointer", m_ptr); track_copy_created((ref_tag*) this);
    }

    /// Move constructor
    ref(ref &&r) : m_ptr(r.m_ptr) {
-        std::cout << "Initialized ref with move from ref " << r.m_ptr << std::endl;
        r.m_ptr = nullptr; 
+
+        print_move_created(this, "with pointer", m_ptr); track_move_created((ref_tag*) this);
    }

    /// Destroy this reference
    ~ref() {
-        std::cout << "Destructing ref " << m_ptr << std::endl;
        if (m_ptr)
            ((Object *) m_ptr)->decRef();
+
+        print_destroyed(this); track_destroyed((ref_tag*) this);
    }

    /// Move another reference into the current one
 	ref& operator=(ref&& r) {
-        std::cout << "Move-assigning ref " << r.m_ptr << std::endl;
+        print_move_assigned(this, "pointer", r.m_ptr); track_move_assigned((ref_tag*) this);
+
 		if (*this == r)
 			return *this;
 		if (m_ptr)
@ -97,7 +110,8 @@ public:

 	/// Overwrite this reference with another reference
 	ref& operator=(const ref& r) {
-        std::cout << "Assigning ref " << r.m_ptr << std::endl;
+        print_copy_assigned(this, "pointer", r.m_ptr); track_copy_assigned((ref_tag*) this);
+
 		if (m_ptr == r.m_ptr)
 			return *this;
 		if (m_ptr)
@ -110,7 +124,8 @@ public:

 	/// Overwrite this reference with a pointer to another object
 	ref& operator=(T *ptr) {
-        std::cout << "Assigning ptr " << ptr << " to ref" << std::endl;
+        print_values(this, "assigned pointer"); track_values((ref_tag*) this, "assigned pointer");
+
 		if (m_ptr == ptr)
 			return *this;
 		if (m_ptr)
--- a/example/run_test.py
+++ b/example/run_test.py
@ -9,14 +9,16 @@ remove_long_marker    = re.compile(r'([0-9])L')
 remove_hex            = re.compile(r'0x[0-9a-fA-F]+')
 shorten_floats        = re.compile(r'([1-9][0-9]*\.[0-9]{4})[0-9]*')

-relaxed = False
-
 def sanitize(lines):
    lines = lines.split('\n')
    for i in range(len(lines)):
        line = lines[i]
        if line.startswith(" |"):
            line = ""
+        if line.startswith("### "):
+            # Constructor/destructor output.  Useful for example, but unreliable across compilers;
+            # testing of proper construction/destruction occurs with ConstructorStats mechanism instead
+            line = ""
        line = remove_unicode_marker.sub(r'\1', line)
        line = remove_long_marker.sub(r'\1', line)
        line = remove_hex.sub(r'0', line)
@ -28,13 +30,6 @@ def sanitize(lines):
        line = line.replace('example.EMode', 'EMode')
        line = line.replace('method of builtins.PyCapsule instance', '')
        line = line.strip()
-        if relaxed:
-            lower = line.lower()
-            # The precise pattern of allocations and deallocations is dependent on the compiler
-            # and optimization level, so we unfortunately can't reliably check it in this kind of test case
-            if 'constructor' in lower or 'destructor' in lower \
-               or 'ref' in lower or 'freeing' in lower:
-                line = ""
        lines[i] = line

    return '\n'.join(sorted([l for l in lines if l != ""]))
@ -44,16 +39,12 @@ if path != '':
    os.chdir(path)

 if len(sys.argv) < 2:
-    print("Syntax: %s [--relaxed] <test name>" % sys.argv[0])
+    print("Syntax: %s <test name>" % sys.argv[0])
    exit(0)

-if len(sys.argv) == 3 and sys.argv[1] == '--relaxed':
-    del sys.argv[1]
-    relaxed = True
-
 name = sys.argv[1]
 try:
-    output_bytes = subprocess.check_output([sys.executable, name + ".py"],
+    output_bytes = subprocess.check_output([sys.executable, "-u", name + ".py"],
                                           stderr=subprocess.STDOUT)
 except subprocess.CalledProcessError as e:
    if e.returncode == 99: