Converter implementation in Python: class versus module?

Question

I've written a little library that uses the builtin ast library to convert between functions, docstrings, argparse .add_argument, classes, and [soon] more.

Stubs look something like this, with ir referring to 'intermediate representation'; i.e., a common internal data-structure that everything parses to and emits from:

def argparse_to_ir
def class_to_ir
def docstring_to_ir
def function_to_ir
# Actually had roundtrip ones also
# like `def argparse2class`

Similarly:

def ir_to_argparse
def ir_to_class
…

Earlier today I refactored these for readability and usability. One I reworked into a module called ir.py, and renamed the functions so you would do import ir followed by ir.from_argparse.

The other I tried the more class-based OO style, had a base ABC class with to_argparse, to_class, &etc.; and specialised with a new class for each type that just created a new def __init__ with different parameters (based on input). So now you do:

ArgparseTransformer(argparse_ast, **common_kwargs).to_class()  # `.to_argparse()`
ClassTransformer(class_def_ast, **common_kwargs).to_class()    # or `.to_method()`

PS: There is no need for a unified interface to infer what the input type is.

Which approach is better, the [explosion of] classes one, or the one which requires knowledge of the internal data-structure?

PPS: Open to alternative 3rd+ choices!

Answer 1

Ended up removing all classes in my codebase—outside of unittest.TestCase)—and just using defs:

In [1]: import doctrans.transformers
In [2]: doctrans.transformers.__all__
Out[3]: ['to_argparse_function', 'to_class', 'to_docstring',
         'to_file', 'to_function']
In [4]: import doctrans.docstring_struct
In [5]: doctrans.docstring_struct.__all__
Out[6]: ['from_class', 'from_class_with_method', 'from_function',
         'from_argparse_ast', 'from_docstring', 'from_docstring_parser']

Leaving me with an SDK like:

transformers.to_file(
    transformers.to_function(
        docstring_struct.from_class_with_method(
            class_with_method_and_body_types_ast, "method_name"
        ),
        emit_default_doc=False,
        function_name="method_name",
        function_type="self"
    )
    filename='classy.py', skip_black=False)
)

(obviously I need a better name than docstring_struct)

Which works reasonably well…