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test_virtual_functions.cpp
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/*
tests/test_virtual_functions.cpp -- overriding virtual functions from Python
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#include "pybind11_tests.h"
#include "constructor_stats.h"
#include <pybind11/functional.h>
#include <thread>
/* This is an example class that we'll want to be able to extend from Python */
class ExampleVirt {
public:
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; }
virtual ~ExampleVirt() { print_destroyed(this); }
virtual int run(int value) {
py::print("Original implementation of "
"ExampleVirt::run(state={}, value={}, str1={}, str2={})"_s.format(state, value, get_string1(), *get_string2()));
return state + value;
}
virtual bool run_bool() = 0;
virtual void pure_virtual() = 0;
// Returning a reference/pointer to a type converted from python (numbers, strings, etc.) is a
// bit trickier, because the actual int& or std::string& or whatever only exists temporarily, so
// we have to handle it specially in the trampoline class (see below).
virtual const std::string &get_string1() { return str1; }
virtual const std::string *get_string2() { return &str2; }
private:
int state;
const std::string str1{"default1"}, str2{"default2"};
};
/* This is a wrapper class that must be generated */
class PyExampleVirt : public ExampleVirt {
public:
using ExampleVirt::ExampleVirt; /* Inherit constructors */
int run(int value) override {
/* Generate wrapping code that enables native function overloading */
PYBIND11_OVERLOAD(
int, /* Return type */
ExampleVirt, /* Parent class */
run, /* Name of function */
value /* Argument(s) */
);
}
bool run_bool() override {
PYBIND11_OVERLOAD_PURE(
bool, /* Return type */
ExampleVirt, /* Parent class */
run_bool, /* Name of function */
/* This function has no arguments. The trailing comma
in the previous line is needed for some compilers */
);
}
void pure_virtual() override {
PYBIND11_OVERLOAD_PURE(
void, /* Return type */
ExampleVirt, /* Parent class */
pure_virtual, /* Name of function */
/* This function has no arguments. The trailing comma
in the previous line is needed for some compilers */
);
}
// We can return reference types for compatibility with C++ virtual interfaces that do so, but
// note they have some significant limitations (see the documentation).
const std::string &get_string1() override {
PYBIND11_OVERLOAD(
const std::string &, /* Return type */
ExampleVirt, /* Parent class */
get_string1, /* Name of function */
/* (no arguments) */
);
}
const std::string *get_string2() override {
PYBIND11_OVERLOAD(
const std::string *, /* Return type */
ExampleVirt, /* Parent class */
get_string2, /* Name of function */
/* (no arguments) */
);
}
};
class NonCopyable {
public:
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;
void operator=(NonCopyable &&) = delete;
std::string get_value() const {
if (value) return std::to_string(*value); else return "(null)";
}
~NonCopyable() { print_destroyed(this); }
private:
std::unique_ptr<int> value;
};
// This is like the above, but is both copy and movable. In effect this means it should get moved
// when it is not referenced elsewhere, but copied if it is still referenced.
class Movable {
public:
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); }
std::string get_value() const { return std::to_string(value); }
~Movable() { print_destroyed(this); }
private:
int value;
};
class NCVirt {
public:
virtual NonCopyable get_noncopyable(int a, int b) { return NonCopyable(a, b); }
virtual Movable get_movable(int a, int b) = 0;
std::string print_nc(int a, int b) { return get_noncopyable(a, b).get_value(); }
std::string print_movable(int a, int b) { return get_movable(a, b).get_value(); }
};
class NCVirtTrampoline : public NCVirt {
#if !defined(__INTEL_COMPILER)
NonCopyable get_noncopyable(int a, int b) override {
PYBIND11_OVERLOAD(NonCopyable, NCVirt, get_noncopyable, a, b);
}
#endif
Movable get_movable(int a, int b) override {
PYBIND11_OVERLOAD_PURE(Movable, NCVirt, get_movable, a, b);
}
};
struct Base {
/* for some reason MSVC2015 can't compile this if the function is pure virtual */
virtual std::string dispatch() const { return {}; };
virtual ~Base() = default;
};
struct DispatchIssue : Base {
virtual std::string dispatch() const {
PYBIND11_OVERLOAD_PURE(std::string, Base, dispatch, /* no arguments */);
}
};
static void test_gil() {
{
py::gil_scoped_acquire lock;
py::print("1st lock acquired");
}
{
py::gil_scoped_acquire lock;
py::print("2nd lock acquired");
}
}
static void test_gil_from_thread() {
py::gil_scoped_release release;
std::thread t(test_gil);
t.join();
}
// Forward declaration (so that we can put the main tests here; the inherited virtual approaches are
// rather long).
void initialize_inherited_virtuals(py::module &m);
TEST_SUBMODULE(virtual_functions, m) {
// test_override
py::class_<ExampleVirt, PyExampleVirt>(m, "ExampleVirt")
.def(py::init<int>())
/* Reference original class in function definitions */
.def("run", &ExampleVirt::run)
.def("run_bool", &ExampleVirt::run_bool)
.def("pure_virtual", &ExampleVirt::pure_virtual);
py::class_<NonCopyable>(m, "NonCopyable")
.def(py::init<int, int>());
py::class_<Movable>(m, "Movable")
.def(py::init<int, int>());
// test_move_support
#if !defined(__INTEL_COMPILER)
py::class_<NCVirt, NCVirtTrampoline>(m, "NCVirt")
.def(py::init<>())
.def("get_noncopyable", &NCVirt::get_noncopyable)
.def("get_movable", &NCVirt::get_movable)
.def("print_nc", &NCVirt::print_nc)
.def("print_movable", &NCVirt::print_movable);
#endif
m.def("runExampleVirt", [](ExampleVirt *ex, int value) { return ex->run(value); });
m.def("runExampleVirtBool", [](ExampleVirt* ex) { return ex->run_bool(); });
m.def("runExampleVirtVirtual", [](ExampleVirt *ex) { ex->pure_virtual(); });
m.def("cstats_debug", &ConstructorStats::get<ExampleVirt>);
initialize_inherited_virtuals(m);
// test_alias_delay_initialization1
// don't invoke Python dispatch classes by default when instantiating C++ classes
// that were not extended on the Python side
struct A {
virtual ~A() {}
virtual void f() { py::print("A.f()"); }
};
struct PyA : A {
PyA() { py::print("PyA.PyA()"); }
~PyA() { py::print("PyA.~PyA()"); }
void f() override {
py::print("PyA.f()");
// This convolution just gives a `void`, but tests that PYBIND11_TYPE() works to protect
// a type containing a ,
PYBIND11_OVERLOAD(PYBIND11_TYPE(typename std::enable_if<true, void>::type), A, f);
}
};
py::class_<A, PyA>(m, "A")
.def(py::init<>())
.def("f", &A::f);
m.def("call_f", [](A *a) { a->f(); });
// test_alias_delay_initialization2
// ... unless we explicitly request it, as in this example:
struct A2 {
virtual ~A2() {}
virtual void f() { py::print("A2.f()"); }
};
struct PyA2 : A2 {
PyA2() { py::print("PyA2.PyA2()"); }
~PyA2() { py::print("PyA2.~PyA2()"); }
void f() override {
py::print("PyA2.f()");
PYBIND11_OVERLOAD(void, A2, f);
}
};
py::class_<A2, PyA2>(m, "A2")
.def(py::init_alias<>())
.def(py::init([](int) { return new PyA2(); }))
.def("f", &A2::f);
m.def("call_f", [](A2 *a2) { a2->f(); });
// test_dispatch_issue
// #159: virtual function dispatch has problems with similar-named functions
py::class_<Base, DispatchIssue>(m, "DispatchIssue")
.def(py::init<>())
.def("dispatch", &Base::dispatch);
m.def("dispatch_issue_go", [](const Base * b) { return b->dispatch(); });
// test_override_ref
// #392/397: overriding reference-returning functions
class OverrideTest {
public:
struct A { std::string value = "hi"; };
std::string v;
A a;
explicit OverrideTest(const std::string &v) : v{v} {}
virtual std::string str_value() { return v; }
virtual std::string &str_ref() { return v; }
virtual A A_value() { return a; }
virtual A &A_ref() { return a; }
virtual ~OverrideTest() = default;
};
class PyOverrideTest : public OverrideTest {
public:
using OverrideTest::OverrideTest;
std::string str_value() override { PYBIND11_OVERLOAD(std::string, OverrideTest, str_value); }
// Not allowed (uncommenting should hit a static_assert failure): we can't get a reference
// to a python numeric value, since we only copy values in the numeric type caster:
// std::string &str_ref() override { PYBIND11_OVERLOAD(std::string &, OverrideTest, str_ref); }
// But we can work around it like this:
private:
std::string _tmp;
std::string str_ref_helper() { PYBIND11_OVERLOAD(std::string, OverrideTest, str_ref); }
public:
std::string &str_ref() override { return _tmp = str_ref_helper(); }
A A_value() override { PYBIND11_OVERLOAD(A, OverrideTest, A_value); }
A &A_ref() override { PYBIND11_OVERLOAD(A &, OverrideTest, A_ref); }
};
py::class_<OverrideTest::A>(m, "OverrideTest_A")
.def_readwrite("value", &OverrideTest::A::value);
py::class_<OverrideTest, PyOverrideTest>(m, "OverrideTest")
.def(py::init<const std::string &>())
.def("str_value", &OverrideTest::str_value)
// .def("str_ref", &OverrideTest::str_ref)
.def("A_value", &OverrideTest::A_value)
.def("A_ref", &OverrideTest::A_ref);
}
// Inheriting virtual methods. We do two versions here: the repeat-everything version and the
// templated trampoline versions mentioned in docs/advanced.rst.
//
// These base classes are exactly the same, but we technically need distinct
// classes for this example code because we need to be able to bind them
// properly (pybind11, sensibly, doesn't allow us to bind the same C++ class to
// multiple python classes).
class A_Repeat {
#define A_METHODS \
public: \
virtual int unlucky_number() = 0; \
virtual std::string say_something(unsigned times) { \
std::string s = ""; \
for (unsigned i = 0; i < times; ++i) \
s += "hi"; \
return s; \
} \
std::string say_everything() { \
return say_something(1) + " " + std::to_string(unlucky_number()); \
}
A_METHODS
virtual ~A_Repeat() = default;
};
class B_Repeat : public A_Repeat {
#define B_METHODS \
public: \
int unlucky_number() override { return 13; } \
std::string say_something(unsigned times) override { \
return "B says hi " + std::to_string(times) + " times"; \
} \
virtual double lucky_number() { return 7.0; }
B_METHODS
};
class C_Repeat : public B_Repeat {
#define C_METHODS \
public: \
int unlucky_number() override { return 4444; } \
double lucky_number() override { return 888; }
C_METHODS
};
class D_Repeat : public C_Repeat {
#define D_METHODS // Nothing overridden.
D_METHODS
};
// Base classes for templated inheritance trampolines. Identical to the repeat-everything version:
class A_Tpl { A_METHODS; virtual ~A_Tpl() = default; };
class B_Tpl : public A_Tpl { B_METHODS };
class C_Tpl : public B_Tpl { C_METHODS };
class D_Tpl : public C_Tpl { D_METHODS };
// Inheritance approach 1: each trampoline gets every virtual method (11 in total)
class PyA_Repeat : public A_Repeat {
public:
using A_Repeat::A_Repeat;
int unlucky_number() override { PYBIND11_OVERLOAD_PURE(int, A_Repeat, unlucky_number, ); }
std::string say_something(unsigned times) override { PYBIND11_OVERLOAD(std::string, A_Repeat, say_something, times); }
};
class PyB_Repeat : public B_Repeat {
public:
using B_Repeat::B_Repeat;
int unlucky_number() override { PYBIND11_OVERLOAD(int, B_Repeat, unlucky_number, ); }
std::string say_something(unsigned times) override { PYBIND11_OVERLOAD(std::string, B_Repeat, say_something, times); }
double lucky_number() override { PYBIND11_OVERLOAD(double, B_Repeat, lucky_number, ); }
};
class PyC_Repeat : public C_Repeat {
public:
using C_Repeat::C_Repeat;
int unlucky_number() override { PYBIND11_OVERLOAD(int, C_Repeat, unlucky_number, ); }
std::string say_something(unsigned times) override { PYBIND11_OVERLOAD(std::string, C_Repeat, say_something, times); }
double lucky_number() override { PYBIND11_OVERLOAD(double, C_Repeat, lucky_number, ); }
};
class PyD_Repeat : public D_Repeat {
public:
using D_Repeat::D_Repeat;
int unlucky_number() override { PYBIND11_OVERLOAD(int, D_Repeat, unlucky_number, ); }
std::string say_something(unsigned times) override { PYBIND11_OVERLOAD(std::string, D_Repeat, say_something, times); }
double lucky_number() override { PYBIND11_OVERLOAD(double, D_Repeat, lucky_number, ); }
};
// Inheritance approach 2: templated trampoline classes.
//
// Advantages:
// - we have only 2 (template) class and 4 method declarations (one per virtual method, plus one for
// any override of a pure virtual method), versus 4 classes and 6 methods (MI) or 4 classes and 11
// methods (repeat).
// - Compared to MI, we also don't have to change the non-trampoline inheritance to virtual, and can
// properly inherit constructors.
//
// Disadvantage:
// - the compiler must still generate and compile 14 different methods (more, even, than the 11
// required for the repeat approach) instead of the 6 required for MI. (If there was no pure
// method (or no pure method override), the number would drop down to the same 11 as the repeat
// approach).
template <class Base = A_Tpl>
class PyA_Tpl : public Base {
public:
using Base::Base; // Inherit constructors
int unlucky_number() override { PYBIND11_OVERLOAD_PURE(int, Base, unlucky_number, ); }
std::string say_something(unsigned times) override { PYBIND11_OVERLOAD(std::string, Base, say_something, times); }
};
template <class Base = B_Tpl>
class PyB_Tpl : public PyA_Tpl<Base> {
public:
using PyA_Tpl<Base>::PyA_Tpl; // Inherit constructors (via PyA_Tpl's inherited constructors)
int unlucky_number() override { PYBIND11_OVERLOAD(int, Base, unlucky_number, ); }
double lucky_number() override { PYBIND11_OVERLOAD(double, Base, lucky_number, ); }
};
// Since C_Tpl and D_Tpl don't declare any new virtual methods, we don't actually need these (we can
// use PyB_Tpl<C_Tpl> and PyB_Tpl<D_Tpl> for the trampoline classes instead):
/*
template <class Base = C_Tpl> class PyC_Tpl : public PyB_Tpl<Base> {
public:
using PyB_Tpl<Base>::PyB_Tpl;
};
template <class Base = D_Tpl> class PyD_Tpl : public PyC_Tpl<Base> {
public:
using PyC_Tpl<Base>::PyC_Tpl;
};
*/
void initialize_inherited_virtuals(py::module &m) {
// test_inherited_virtuals
// Method 1: repeat
py::class_<A_Repeat, PyA_Repeat>(m, "A_Repeat")
.def(py::init<>())
.def("unlucky_number", &A_Repeat::unlucky_number)
.def("say_something", &A_Repeat::say_something)
.def("say_everything", &A_Repeat::say_everything);
py::class_<B_Repeat, A_Repeat, PyB_Repeat>(m, "B_Repeat")
.def(py::init<>())
.def("lucky_number", &B_Repeat::lucky_number);
py::class_<C_Repeat, B_Repeat, PyC_Repeat>(m, "C_Repeat")
.def(py::init<>());
py::class_<D_Repeat, C_Repeat, PyD_Repeat>(m, "D_Repeat")
.def(py::init<>());
// test_
// Method 2: Templated trampolines
py::class_<A_Tpl, PyA_Tpl<>>(m, "A_Tpl")
.def(py::init<>())
.def("unlucky_number", &A_Tpl::unlucky_number)
.def("say_something", &A_Tpl::say_something)
.def("say_everything", &A_Tpl::say_everything);
py::class_<B_Tpl, A_Tpl, PyB_Tpl<>>(m, "B_Tpl")
.def(py::init<>())
.def("lucky_number", &B_Tpl::lucky_number);
py::class_<C_Tpl, B_Tpl, PyB_Tpl<C_Tpl>>(m, "C_Tpl")
.def(py::init<>());
py::class_<D_Tpl, C_Tpl, PyB_Tpl<D_Tpl>>(m, "D_Tpl")
.def(py::init<>());
// Fix issue #1454 (crash when acquiring/releasing GIL on another thread in Python 2.7)
m.def("test_gil", &test_gil);
m.def("test_gil_from_thread", &test_gil_from_thread);
};

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