test_virtual_functions.py

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from __future__ import annotations
 
import sys
 
import pytest
 
import env  # noqa: F401
 
m = pytest.importorskip("pybind11_tests.virtual_functions")
from pybind11_tests import ConstructorStats  # noqa: E402
 
 
def test_override(capture, msg):
    class ExtendedExampleVirt(m.ExampleVirt):
        def __init__(self, state):
            super().__init__(state + 1)
            self.data = "Hello world"
 
        def run(self, value):
            print(f"ExtendedExampleVirt::run({value}), calling parent..")
            return super().run(value + 1)
 
        def run_bool(self):
            print("ExtendedExampleVirt::run_bool()")
            return False
 
        def get_string1(self):
            return "override1"
 
        def pure_virtual(self):
            print(f"ExtendedExampleVirt::pure_virtual(): {self.data}")
 
    class ExtendedExampleVirt2(ExtendedExampleVirt):
        def __init__(self, state):
            super().__init__(state + 1)
 
        def get_string2(self):
            return "override2"
 
    ex12 = m.ExampleVirt(10)
    with capture:
        assert m.runExampleVirt(ex12, 20) == 30
    assert (
        capture
        == """
        Original implementation of ExampleVirt::run(state=10, value=20, str1=default1, str2=default2)
    """
    )
 
    with pytest.raises(RuntimeError) as excinfo:
        m.runExampleVirtVirtual(ex12)
    assert (
        msg(excinfo.value)
        == 'Tried to call pure virtual function "ExampleVirt::pure_virtual"'
    )
 
    ex12p = ExtendedExampleVirt(10)
    with capture:
        assert m.runExampleVirt(ex12p, 20) == 32
    assert (
        capture
        == """
        ExtendedExampleVirt::run(20), calling parent..
        Original implementation of ExampleVirt::run(state=11, value=21, str1=override1, str2=default2)
    """
    )
    with capture:
        assert m.runExampleVirtBool(ex12p) is False
    assert capture == "ExtendedExampleVirt::run_bool()"
    with capture:
        m.runExampleVirtVirtual(ex12p)
    assert capture == "ExtendedExampleVirt::pure_virtual(): Hello world"
 
    ex12p2 = ExtendedExampleVirt2(15)
    with capture:
        assert m.runExampleVirt(ex12p2, 50) == 68
    assert (
        capture
        == """
        ExtendedExampleVirt::run(50), calling parent..
        Original implementation of ExampleVirt::run(state=17, value=51, str1=override1, str2=override2)
    """
    )
 
    cstats = ConstructorStats.get(m.ExampleVirt)
    assert cstats.alive() == 3
    del ex12, ex12p, ex12p2
    assert cstats.alive() == 0
    assert cstats.values() == ["10", "11", "17"]
    assert cstats.copy_constructions == 0
    assert cstats.move_constructions >= 0
 
 
def test_alias_delay_initialization1(capture):
    """`A` only initializes its trampoline class when we inherit from it
 
    If we just create and use an A instance directly, the trampoline initialization is
    bypassed and we only initialize an A() instead (for performance reasons).
    """
 
    class B(m.A):
        def __init__(self):
            super().__init__()
 
        def f(self):
            print("In python f()")
 
    # C++ version
    with capture:
        a = m.A()
        m.call_f(a)
        del a
        pytest.gc_collect()
    assert capture == "A.f()"
 
    # Python version
    with capture:
        b = B()
        m.call_f(b)
        del b
        pytest.gc_collect()
    assert (
        capture
        == """
        PyA.PyA()
        PyA.f()
        In python f()
        PyA.~PyA()
    """
    )
 
 
def test_alias_delay_initialization2(capture):
    """`A2`, unlike the above, is configured to always initialize the alias
 
    While the extra initialization and extra class layer has small virtual dispatch
    performance penalty, it also allows us to do more things with the trampoline
    class such as defining local variables and performing construction/destruction.
    """
 
    class B2(m.A2):
        def __init__(self):
            super().__init__()
 
        def f(self):
            print("In python B2.f()")
 
    # No python subclass version
    with capture:
        a2 = m.A2()
        m.call_f(a2)
        del a2
        pytest.gc_collect()
        a3 = m.A2(1)
        m.call_f(a3)
        del a3
        pytest.gc_collect()
    assert (
        capture
        == """
        PyA2.PyA2()
        PyA2.f()
        A2.f()
        PyA2.~PyA2()
        PyA2.PyA2()
        PyA2.f()
        A2.f()
        PyA2.~PyA2()
    """
    )
 
    # Python subclass version
    with capture:
        b2 = B2()
        m.call_f(b2)
        del b2
        pytest.gc_collect()
    assert (
        capture
        == """
        PyA2.PyA2()
        PyA2.f()
        In python B2.f()
        PyA2.~PyA2()
    """
    )
 
 
# PyPy: Reference count > 1 causes call with noncopyable instance
# to fail in ncv1.print_nc()
@pytest.mark.xfail("env.PYPY")
@pytest.mark.skipif(
    not hasattr(m, "NCVirt"), reason="NCVirt does not work on Intel/PGI/NVCC compilers"
)
def test_move_support():
    class NCVirtExt(m.NCVirt):
        def get_noncopyable(self, a, b):
            # Constructs and returns a new instance:
            return m.NonCopyable(a * a, b * b)
 
        def get_movable(self, a, b):
            # Return a referenced copy
            self.movable = m.Movable(a, b)
            return self.movable
 
    class NCVirtExt2(m.NCVirt):
        def get_noncopyable(self, a, b):
            # Keep a reference: this is going to throw an exception
            self.nc = m.NonCopyable(a, b)
            return self.nc
 
        def get_movable(self, a, b):
            # Return a new instance without storing it
            return m.Movable(a, b)
 
    ncv1 = NCVirtExt()
    assert ncv1.print_nc(2, 3) == "36"
    assert ncv1.print_movable(4, 5) == "9"
    ncv2 = NCVirtExt2()
    assert ncv2.print_movable(7, 7) == "14"
    # Don't check the exception message here because it differs under debug/non-debug mode
    with pytest.raises(RuntimeError):
        ncv2.print_nc(9, 9)
 
    nc_stats = ConstructorStats.get(m.NonCopyable)
    mv_stats = ConstructorStats.get(m.Movable)
    assert nc_stats.alive() == 1
    assert mv_stats.alive() == 1
    del ncv1, ncv2
    assert nc_stats.alive() == 0
    assert mv_stats.alive() == 0
    assert nc_stats.values() == ["4", "9", "9", "9"]
    assert mv_stats.values() == ["4", "5", "7", "7"]
    assert nc_stats.copy_constructions == 0
    assert mv_stats.copy_constructions == 1
    assert nc_stats.move_constructions >= 0
    assert mv_stats.move_constructions >= 0
 
 
def test_dispatch_issue(msg):
    """#159: virtual function dispatch has problems with similar-named functions"""
 
    class PyClass1(m.DispatchIssue):
        def dispatch(self):
            return "Yay.."
 
    class PyClass2(m.DispatchIssue):
        def dispatch(self):
            with pytest.raises(RuntimeError) as excinfo:
                super().dispatch()
            assert (
                msg(excinfo.value)
                == 'Tried to call pure virtual function "Base::dispatch"'
            )
 
            return m.dispatch_issue_go(PyClass1())
 
    b = PyClass2()
    assert m.dispatch_issue_go(b) == "Yay.."
 
 
def test_recursive_dispatch_issue():
    """#3357: Recursive dispatch fails to find python function override"""
 
    class Data(m.Data):
        def __init__(self, value):
            super().__init__()
            self.value = value
 
    class Adder(m.Adder):
        def __call__(self, first, second, visitor):
            # lambda is a workaround, which adds extra frame to the
            # current CPython thread. Removing lambda reveals the bug
            # [https://github.com/pybind/pybind11/issues/3357]
            (lambda: visitor(Data(first.value + second.value)))()  # noqa: PLC3002
 
    class StoreResultVisitor:
        def __init__(self):
            self.result = None
 
        def __call__(self, data):
            self.result = data.value
 
    store = StoreResultVisitor()
 
    m.add2(Data(1), Data(2), Adder(), store)
    assert store.result == 3
 
    # without lambda in Adder class, this function fails with
    # RuntimeError: Tried to call pure virtual function "AdderBase::__call__"
    m.add3(Data(1), Data(2), Data(3), Adder(), store)
    assert store.result == 6
 
 
def test_override_ref():
    """#392/397: overriding reference-returning functions"""
    o = m.OverrideTest("asdf")
 
    # Not allowed (see associated .cpp comment)
    # i = o.str_ref()
    # assert o.str_ref() == "asdf"
    assert o.str_value() == "asdf"
 
    assert o.A_value().value == "hi"
    a = o.A_ref()
    assert a.value == "hi"
    a.value = "bye"
    assert a.value == "bye"
 
 
def test_inherited_virtuals():
    class AR(m.A_Repeat):
        def unlucky_number(self):
            return 99
 
    class AT(m.A_Tpl):
        def unlucky_number(self):
            return 999
 
    obj = AR()
    assert obj.say_something(3) == "hihihi"
    assert obj.unlucky_number() == 99
    assert obj.say_everything() == "hi 99"
 
    obj = AT()
    assert obj.say_something(3) == "hihihi"
    assert obj.unlucky_number() == 999
    assert obj.say_everything() == "hi 999"
 
    for obj in [m.B_Repeat(), m.B_Tpl()]:
        assert obj.say_something(3) == "B says hi 3 times"
        assert obj.unlucky_number() == 13
        assert obj.lucky_number() == 7.0
        assert obj.say_everything() == "B says hi 1 times 13"
 
    for obj in [m.C_Repeat(), m.C_Tpl()]:
        assert obj.say_something(3) == "B says hi 3 times"
        assert obj.unlucky_number() == 4444
        assert obj.lucky_number() == 888.0
        assert obj.say_everything() == "B says hi 1 times 4444"
 
    class CR(m.C_Repeat):
        def lucky_number(self):
            return m.C_Repeat.lucky_number(self) + 1.25
 
    obj = CR()
    assert obj.say_something(3) == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 889.25
    assert obj.say_everything() == "B says hi 1 times 4444"
 
    class CT(m.C_Tpl):
        pass
 
    obj = CT()
    assert obj.say_something(3) == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 888.0
    assert obj.say_everything() == "B says hi 1 times 4444"
 
    class CCR(CR):
        def lucky_number(self):
            return CR.lucky_number(self) * 10
 
    obj = CCR()
    assert obj.say_something(3) == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 8892.5
    assert obj.say_everything() == "B says hi 1 times 4444"
 
    class CCT(CT):
        def lucky_number(self):
            return CT.lucky_number(self) * 1000
 
    obj = CCT()
    assert obj.say_something(3) == "B says hi 3 times"
    assert obj.unlucky_number() == 4444
    assert obj.lucky_number() == 888000.0
    assert obj.say_everything() == "B says hi 1 times 4444"
 
    class DR(m.D_Repeat):
        def unlucky_number(self):
            return 123
 
        def lucky_number(self):
            return 42.0
 
    for obj in [m.D_Repeat(), m.D_Tpl()]:
        assert obj.say_something(3) == "B says hi 3 times"
        assert obj.unlucky_number() == 4444
        assert obj.lucky_number() == 888.0
        assert obj.say_everything() == "B says hi 1 times 4444"
 
    obj = DR()
    assert obj.say_something(3) == "B says hi 3 times"
    assert obj.unlucky_number() == 123
    assert obj.lucky_number() == 42.0
    assert obj.say_everything() == "B says hi 1 times 123"
 
    class DT(m.D_Tpl):
        def say_something(self, times):
            return "DT says:" + (" quack" * times)
 
        def unlucky_number(self):
            return 1234
 
        def lucky_number(self):
            return -4.25
 
    obj = DT()
    assert obj.say_something(3) == "DT says: quack quack quack"
    assert obj.unlucky_number() == 1234
    assert obj.lucky_number() == -4.25
    assert obj.say_everything() == "DT says: quack 1234"
 
    class DT2(DT):
        def say_something(self, times):
            return "DT2: " + ("QUACK" * times)
 
        def unlucky_number(self):
            return -3
 
    class BT(m.B_Tpl):
        def say_something(self, times):
            return "BT" * times
 
        def unlucky_number(self):
            return -7
 
        def lucky_number(self):
            return -1.375
 
    obj = BT()
    assert obj.say_something(3) == "BTBTBT"
    assert obj.unlucky_number() == -7
    assert obj.lucky_number() == -1.375
    assert obj.say_everything() == "BT -7"
 
 
@pytest.mark.skipif(sys.platform.startswith("emscripten"), reason="Requires threads")
def test_issue_1454():
    # Fix issue #1454 (crash when acquiring/releasing GIL on another thread in Python 2.7)
    m.test_gil()
    m.test_gil_from_thread()
 
 
def test_python_override():
    def func():
        class Test(m.test_override_cache_helper):
            def func(self):
                return 42
 
        return Test()
 
    def func2():
        class Test(m.test_override_cache_helper):
            pass
 
        return Test()
 
    for _ in range(1500):
        assert m.test_override_cache(func()) == 42
        assert m.test_override_cache(func2()) == 0