The linked-to example uses a query-dependent expression which resists easy pre-compilation. The author says the overhead of building a Python expression as a st

The linked-to example uses a query-dependent expression which resists easy pre-compilation. The author says the overhead of building a Python expression as a string then byte compiling it is too high, which would also hold for a ctypes/cffi implementation. In my case I had a lot of config dictionaries like: default_output_args = { "tsv": {"sep": "tab", "quoting": "always"}, "csv": {"sep": "comma", "quoting": "always"}, "json": {"indent": None, "allow_nan": True}, ... } and a generic API like: def open_writer(destination, format="csv", output_args=None): ... which would let 'format' specify the output format, with the corresponding default arguments, and with the output_args able to override the defaults. I found the generic API too annoying when I knew I wanted a given format, so I added format-specific APIs with kwargs set to the default values, like: def open_csv_writer(destination, sep="tab", quoting="always"): ... def open_json_writer(destination, indent=None, allow_nan=True): ... And I wanted to keep the generic API and format-specific APIs synchronized, because the generic API is useful too. My original version processed default_output_args to generate the byte code for the different writer functions, setting up the function definitions correctly. This is not something which can be done with ctypes.