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Added support for exposing classes with private destructors and corresponding documentation
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@ -942,6 +942,37 @@ In other words, :func:`init` creates an anonymous function that invokes an
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in-place constructor. Memory allocation etc. is already take care of beforehand
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in-place constructor. Memory allocation etc. is already take care of beforehand
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within pybind11.
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within pybind11.
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.. _classes_with_non_public_destructors:
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Classes with non-public destructors
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===================================
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If a class has a private or protected destructor, as might be the case in a singleton
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pattern for example, a compile error will occur when trying to expose the class because
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the std::unique_ptr holding the instance of the class will attempt to call its destructor
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when de-allocating the instance. In order to expose classes with private or protected
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destructors you can override the ``holder_type`` and provide a custom destructor. Pybind11
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provides a blank destructor for you to use as follows
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.. code-block:: cpp
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/* ... definition ... */
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class MyClass {
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~MyClass() {}
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};
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/* ... binding code ... */
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py::class_<MyClass, std::unique_ptr<MyClass, py::blank_deleter<MyClass>>(m, "MyClass")
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.def(py::init<>)
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The blank destructor provided by Pybind11 is a no-op, so you will still need to make sure
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you are cleaning up the memory in C++. Additionally, the blank destructor, or any custom
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destructor you provide to the unique_ptr will only be called if the object is initialized
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within Python. If the object is initialized in C++ via a getter function, the deleter will
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not be called at all.
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.. _catching_and_throwing_exceptions:
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.. _catching_and_throwing_exceptions:
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Catching and throwing exceptions
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Catching and throwing exceptions
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@ -350,4 +350,11 @@ PYBIND11_DECL_FMT(float, "f");
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PYBIND11_DECL_FMT(double, "d");
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PYBIND11_DECL_FMT(double, "d");
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PYBIND11_DECL_FMT(bool, "?");
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PYBIND11_DECL_FMT(bool, "?");
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// Helper class for exposing classes with a private destructor by overriding the deleter object of std::unique_ptr
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template <typename T>
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struct blank_deleter
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{
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void operator()(T*) {}
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};
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NAMESPACE_END(pybind11)
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NAMESPACE_END(pybind11)
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