Cppyy

Presented by Wim Lavrijsen, LBL at the September 2, 2021 compiler research meeting (https://compiler-research.org/meeting...)

Abstract:
cppyy provides automatic Python bindings to C++ code, at runtime, through Cling, the C++ interpreter. Python is itself a dynamic language executed by an interpreter, thus the interaction with C++ code becomes more natural when intermediated by Cling. Examples include runtime template instantiations, callbacks, cross-language inheritance, automatic downcasting, and exception mapping. Many advanced C++ features such as placement new, multiple virtual inheritance, variadic templates, etc., are also naturally handled.

cppyy achieves high performance through an all-lazy approach and specialization of common cases through runtime reflection. As such, it has a much lower call overhead than other binders, notably in its implementation for PyPy, a fully compatible Python interpreter sporting a tracing JIT. Furthermore, cppyy makes maintaining a large software stack simpler: except for cppyy’s own python-interpreter binding, it does not have any compiled code that is Python-dependent. I.e., cppyy-based extension modules require no recompilation when switching Python interpreters.

In this presentation I’ll show the benefits of runtime Python-C++ bindings and give a bird’s eye overview of the implementation underpinning cppyy.