The document discusses using Python for testing C++ code. It provides an agenda that covers QA vs developers, testing frameworks/tools/libraries like Boost.Python and Pybind11. Pybind11 is highlighted as a modern alternative to Boost.Python for binding C++ and Python, offering features like custom data structures, methods, exceptions and STL support with correct reference counting. The conclusion is that Python is useful for tasks like parsing files and providing shell/OS functionality when working with C++.

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Kyrylo Cherneha
C++ developer
C++ & Python
interaction in
automotive industry

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Agenda
QA vs Developers
Testing
Why Python?
Frameworks/Tools/Libraries
Pybind11/Boost.Python
Conclusion

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QA vs Developers

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Unit testing
• Gtest
• CPPtest
• Catch
• Boost.Test
• etc

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Integration testing

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How we do IT
First
component
test
Second
component
test
Integration
test

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Small prinC++

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Why Python?

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Frameworks/Tools/Libraries
https://github.com/cython/cython/wiki/WrappingCorCpp

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Boost.Python
Python programmer walks into a bar and asks for something imported.
The bindings are fast, but the C++ files compile very slowly and it's very difficult to debug
(several pages of C++ errors in templates if you make a mistake in your code).

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Hello

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Pybind11 – Feature Mapping
• Functions accepting and returning custom data structures per value, reference, or pointer
• Instance methods and static methods, Overloaded functions
• Instance attributes and static attributes
• Arbitrary exception types
• Enumerations, Callbacks
• Iterators and ranges, Custom operators
• Single and multiple inheritance
• STL data structures
• Smart pointers with reference counting like std::shared_ptr
• Internal references with correct reference counting
• C++ classes with virtual (and pure virtual) methods can be extended in Python

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Pybind11

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Pybind11 (Continue)
PYBIND11_OVERLOAD_PURE(/*params*/)
PYBIND11_EMBEDDED_MODULE(bindings, m)
// m – is a py::module which is used to bind functions and classes
pybind11 is a header-only library, hence it is not necessary to link against any special libraries and there are
no intermediate (magic) translation steps.
find_package( PythonInterp REQUIRED )
find_package( PythonLibs REQUIRED )

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All you need is … Python

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Comparison of usage
description Boost pybind11
C++, python type convert boost::python::extract
py::cast(cls)
obj.cast<MyClass *>()
Python type in C++
boost::python::list
boost::python::tuple
py::list
py::tuple
Python type in C++ boost::python::make_tuple py::make_tuple
Classe declaration boost::python::class_ py::class_
Classe declaration boost::python::class_("name","descr",init<>)
py::class_(m, "name","descr")
.def(init<>())
Split classe declaration
some file
void bind_matrix() void bind_matrix(py::module& m)
property setter getter .add_property .def_readwrite

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P.S.
• Fast code writing for parsing files (xml, json)
• Some useful features for user (like calling bash/shell, working with directories, OS, processes,
etc)
• Just a joke about PHP (why not?):
• A piece of PHP code walks into a bar. The bartender informs it that they don't serve spaghetti
there, so it turns around and leaves.
• Spoiler for C++23: pointers will be removed.

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Thank you