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Problem ======= The template trampoline pattern documented in PR #322 has a problem with virtual method overloads in intermediate classes in the inheritance chain between the trampoline class and the base class. For example, consider the following inheritance structure, where `B` is the actual class, `PyB<B>` is the trampoline class, and `PyA<B>` is an intermediate class adding A's methods into the trampoline: PyB<B> -> PyA<B> -> B -> A Suppose PyA<B> has a method `some_method()` with a PYBIND11_OVERLOAD in it to overload the virtual `A::some_method()`. If a Python class `C` is defined that inherits from the pybind11-registered `B` and tries to provide an overriding `some_method()`, the PYBIND11_OVERLOADs declared in PyA<B> fails to find this overloaded method, and thus never invoke it (or, if pure virtual and not overridden in PyB<B>, raises an exception). This happens because the base (internal) `PYBIND11_OVERLOAD_INT` macro simply calls `get_overload(this, name)`; `get_overload()` then uses the inferred type of `this` to do a type lookup in `registered_types_cpp`. This is where it fails: `this` will be a `PyA<B> *`, but `PyA<B>` is neither the base type (`B`) nor the trampoline type (`PyB<B>`). As a result, the overload fails and we get a failed overload lookup. The fix ======= The fix is relatively simple: we can cast `this` passed to `get_overload()` to a `const B *`, which lets get_overload look up the correct class. Since trampoline classes should be derived from `B` classes anyway, this cast should be perfectly safe. This does require adding the class name as an argument to the PYBIND11_OVERLOAD_INT macro, but leaves the public macro signatures unchanged.
234 lines
7.5 KiB
Python
234 lines
7.5 KiB
Python
import pytest
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import pybind11_tests
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from pybind11_tests import ConstructorStats
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def test_override(capture, msg):
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from pybind11_tests import (ExampleVirt, runExampleVirt, runExampleVirtVirtual,
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runExampleVirtBool)
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class ExtendedExampleVirt(ExampleVirt):
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def __init__(self, state):
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super(ExtendedExampleVirt, self).__init__(state + 1)
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self.data = "Hello world"
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def run(self, value):
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print('ExtendedExampleVirt::run(%i), calling parent..' % value)
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return super(ExtendedExampleVirt, self).run(value + 1)
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def run_bool(self):
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print('ExtendedExampleVirt::run_bool()')
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return False
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def pure_virtual(self):
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print('ExtendedExampleVirt::pure_virtual(): %s' % self.data)
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ex12 = ExampleVirt(10)
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with capture:
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assert runExampleVirt(ex12, 20) == 30
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assert capture == "Original implementation of ExampleVirt::run(state=10, value=20)"
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with pytest.raises(RuntimeError) as excinfo:
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runExampleVirtVirtual(ex12)
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assert msg(excinfo.value) == 'Tried to call pure virtual function "ExampleVirt::pure_virtual"'
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ex12p = ExtendedExampleVirt(10)
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with capture:
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assert runExampleVirt(ex12p, 20) == 32
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assert capture == """
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ExtendedExampleVirt::run(20), calling parent..
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Original implementation of ExampleVirt::run(state=11, value=21)
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"""
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with capture:
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assert runExampleVirtBool(ex12p) is False
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assert capture == "ExtendedExampleVirt::run_bool()"
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with capture:
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runExampleVirtVirtual(ex12p)
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assert capture == "ExtendedExampleVirt::pure_virtual(): Hello world"
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cstats = ConstructorStats.get(ExampleVirt)
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assert cstats.alive() == 2
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del ex12, ex12p
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assert cstats.alive() == 0
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assert cstats.values() == ['10', '11']
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assert cstats.copy_constructions == 0
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assert cstats.move_constructions >= 0
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def test_inheriting_repeat():
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from pybind11_tests import A_Repeat, B_Repeat, C_Repeat, D_Repeat, A_Tpl, B_Tpl, C_Tpl, D_Tpl
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class VI_AR(A_Repeat):
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def unlucky_number(self):
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return 99
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class VI_AT(A_Tpl):
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def unlucky_number(self):
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return 999
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obj = VI_AR()
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assert obj.say_something(3) == "hihihi"
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assert obj.unlucky_number() == 99
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assert obj.say_everything() == "hi 99"
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obj = VI_AT()
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assert obj.say_something(3) == "hihihi"
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assert obj.unlucky_number() == 999
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assert obj.say_everything() == "hi 999"
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for obj in [B_Repeat(), B_Tpl()]:
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 13
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assert obj.lucky_number() == 7.0
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assert obj.say_everything() == "B says hi 1 times 13"
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for obj in [C_Repeat(), C_Tpl()]:
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 888.0
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assert obj.say_everything() == "B says hi 1 times 4444"
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class VI_CR(C_Repeat):
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def lucky_number(self):
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return C_Repeat.lucky_number(self) + 1.25
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obj = VI_CR()
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 889.25
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assert obj.say_everything() == "B says hi 1 times 4444"
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class VI_CT(C_Tpl):
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pass
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obj = VI_CT()
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 888.0
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assert obj.say_everything() == "B says hi 1 times 4444"
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class VI_CCR(VI_CR):
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def lucky_number(self):
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return VI_CR.lucky_number(self) * 10
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obj = VI_CCR()
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 8892.5
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assert obj.say_everything() == "B says hi 1 times 4444"
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class VI_CCT(VI_CT):
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def lucky_number(self):
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return VI_CT.lucky_number(self) * 1000
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obj = VI_CCT()
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 888000.0
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assert obj.say_everything() == "B says hi 1 times 4444"
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class VI_DR(D_Repeat):
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def unlucky_number(self):
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return 123
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def lucky_number(self):
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return 42.0
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for obj in [D_Repeat(), D_Tpl()]:
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 4444
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assert obj.lucky_number() == 888.0
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assert obj.say_everything() == "B says hi 1 times 4444"
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obj = VI_DR()
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assert obj.say_something(3) == "B says hi 3 times"
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assert obj.unlucky_number() == 123
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assert obj.lucky_number() == 42.0
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assert obj.say_everything() == "B says hi 1 times 123"
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class VI_DT(D_Tpl):
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def say_something(self, times):
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return "VI_DT says:" + (' quack' * times)
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def unlucky_number(self):
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return 1234
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def lucky_number(self):
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return -4.25
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obj = VI_DT()
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assert obj.say_something(3) == "VI_DT says: quack quack quack"
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assert obj.unlucky_number() == 1234
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assert obj.lucky_number() == -4.25
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assert obj.say_everything() == "VI_DT says: quack 1234"
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class VI_DT2(VI_DT):
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def say_something(self, times):
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return "VI_DT2: " + ('QUACK' * times)
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def unlucky_number(self):
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return -3
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class VI_BT(B_Tpl):
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def say_something(self, times):
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return "VI_BT" * times
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def unlucky_number(self):
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return -7
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def lucky_number(self):
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return -1.375
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obj = VI_BT()
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assert obj.say_something(3) == "VI_BTVI_BTVI_BT"
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assert obj.unlucky_number() == -7
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assert obj.lucky_number() == -1.375
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assert obj.say_everything() == "VI_BT -7"
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@pytest.mark.skipif(not hasattr(pybind11_tests, 'NCVirt'),
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reason="NCVirt test broken on ICPC")
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def test_move_support():
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from pybind11_tests import NCVirt, NonCopyable, Movable
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class NCVirtExt(NCVirt):
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def get_noncopyable(self, a, b):
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# Constructs and returns a new instance:
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nc = NonCopyable(a * a, b * b)
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return nc
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def get_movable(self, a, b):
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# Return a referenced copy
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self.movable = Movable(a, b)
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return self.movable
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class NCVirtExt2(NCVirt):
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def get_noncopyable(self, a, b):
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# Keep a reference: this is going to throw an exception
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self.nc = NonCopyable(a, b)
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return self.nc
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def get_movable(self, a, b):
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# Return a new instance without storing it
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return Movable(a, b)
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ncv1 = NCVirtExt()
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assert ncv1.print_nc(2, 3) == "36"
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assert ncv1.print_movable(4, 5) == "9"
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ncv2 = NCVirtExt2()
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assert ncv2.print_movable(7, 7) == "14"
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# Don't check the exception message here because it differs under debug/non-debug mode
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with pytest.raises(RuntimeError):
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ncv2.print_nc(9, 9)
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nc_stats = ConstructorStats.get(NonCopyable)
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mv_stats = ConstructorStats.get(Movable)
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assert nc_stats.alive() == 1
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assert mv_stats.alive() == 1
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del ncv1, ncv2
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assert nc_stats.alive() == 0
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assert mv_stats.alive() == 0
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assert nc_stats.values() == ['4', '9', '9', '9']
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assert mv_stats.values() == ['4', '5', '7', '7']
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assert nc_stats.copy_constructions == 0
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assert mv_stats.copy_constructions == 1
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assert nc_stats.move_constructions >= 0
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assert mv_stats.move_constructions >= 0
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