3.3. Data passing and function calls

Copying data, especially, large arrays, impedes performance, as modern computer architectures are bounded by memory operations. Hence, in Open Interfaces we avoid copying data and pass all data as pointers, which makes all conversion operations fast and cheap. Conversion of integer and floating-point numbers is cheap by itself, but even for arrays, it is a matter of creating a thin wrapper around an~actual data pointer.

To invoke functions between different languages, the Foreign Function Interface (FFI) library libffi library is used, either indirectly, e.g., using ctypes in Python, or explicitly for calling C functions dynamically.

Note that we use C convention of functions returning an integer to indicate an error occurred during a function call. When the resultant integer is zero, the function invocation is successful, and not otherwise. For languages that support exceptions as the error-handling mechanism, an exception is raised on the user side, so that the user does not have to check every function call for errors.