numerals.py

"""
A module for when you find modern numeric notation far too convenient to use
and want to go back to good old fashioned roman numerals.

You can import any numeral you like from here and it will work just fine.
e.g.

>>> from numerals import IX, XVIIIII
>>> IX + XVIIIII
XXIX

Because of the way Python normalizes identifiers you can import any
of these with their unicode equivalent, but also because I am lazy
(and because my console is stupid about some unicode characters which
makes debugging annoying) the repr is ascii only.

"""


def __getattr__(name):
    # Copied from here because I am lazy:
    # https://www.w3resource.com/python-exercises/class-exercises/python-class-exercise-2.php

    try:
        rom_val = {"I": 1, "V": 5, "X": 10, "L": 50, "C": 100, "D": 500, "M": 1000}
        int_val = 0
        for i in range(len(name)):
            if i > 0 and rom_val[name[i]] > rom_val[name[i - 1]]:
                int_val += rom_val[name[i]] - 2 * rom_val[name[i - 1]]
            else:
                int_val += rom_val[name[i]]
        return Numeral(int_val)
    except KeyError:
        return AttributeError(name)


class Numeral(int):
    def __repr__(self):
        # Copied from here because I am lazy
        # https://www.w3resource.com/python-exercises/class-exercises/python-class-exercise-1.php
        val = [1000, 900, 500, 400, 100, 90, 50, 40, 10, 9, 5, 4, 1]
        syb = ["M", "CM", "D", "CD", "C", "XC", "L", "XL", "X", "IX", "V", "IV", "I"]
        roman_num = ""
        i = 0
        num = self
        while num > 0:
            for _ in range(num // val[i]):
                roman_num += syb[i]
                num -= val[i]
            i += 1
        return roman_num


ARITHMETIC_METHODS = [
    "__abs__",
    "__add__",
    "__and__",
    "__bool__",
    "__ceil__",
    "__divmod__",
    "__floor__",
    "__floordiv__",
    "__index__",
    "__int__",
    "__invert__",
    "__lshift__",
    "__mod__",
    "__mul__",
    "__neg__",
    "__or__",
    "__pos__",
    "__pow__",
    "__radd__",
    "__rand__",
    "__rdivmod__",
    "__rfloordiv__",
    "__rlshift__",
    "__rmod__",
    "__rmul__",
    "__ror__",
    "__round__",
    "__rpow__",
    "__rrshift__",
    "__rshift__",
    "__rsub__",
    "__rtruediv__",
    "__rxor__",
    "__sub__",
    "__truediv__",
    "__trunc__",
    "__xor__",
]


def replace_method(name):
    orig = getattr(int, name)

    def accept(*args):
        result = orig(*args)
        if isinstance(result, int) and not isinstance(result, Numeral):
            return Numeral(result)
        else:
            return result

    accept.__name__ = name
    setattr(Numeral, name, accept)


for n in ARITHMETIC_METHODS:
    replace_method(n)