Python元编程，在运行时添加函数

Question

此代码是否有任何问题？它可以工作，但是它是“自省”并即时创建新功能的“ Python方式”吗？例如，与下面的示例 init 方法相比，使用类属性是否有优势？是否有总体上更好的方式进行这样的元编程？还有将输入列入白名单的更好方法吗？我知道白名单在这种情况下不是很有用，但可以将其包括在内以进行查询。

import sys
import re

class Convert:

    whitelist = {
        'pounds': 'kilos',
        'kilos': 'pounds',
        'meters': 'feet',
        'feet': 'meters',
        'farenheit': 'celsius',
        'celsius': 'farenheit',
        'volts': 'gigavolts'
    }

    kilos_to_pounds = lambda self, p: 2.20462  * p
    pounds_to_kilos = lambda self, k: 0.453592 * k
    pounds_to_grams = lambda self, p: p / 1000
    kilos_to_grams = lambda self, k: k * 1000
    meters_to_feet = lambda self, m: 3.28084 * m
    feet_to_meters = lambda self, f: 0.3048 * f
    farenheit_to_celsius = lambda self, f: (f - 32.0) * (5.0/9.0)
    celsius_to_farenheit = lambda self, c: (c * 9.0/5.0) + 32.0

    # can do this also, but is it better? why?:
    def __init__(self):
        self.y_to_z = lambda x: x - x

    def is_allowed(self, source, dest):
        allowed = {
            source: self.whitelist.get(source, None)
            for k,v in self.whitelist.items()
            if source in self.whitelist and self.whitelist[source] == v
        }

        if not allowed:
            raise Exception(f'Cannot convert {source} to {dest}.')
        return True

    def add(self, func, source, dest):
        if self.is_allowed(source, dest):
            setattr(self, '{}_to_{}'.format(source, dest), func)
            return True
        return False

    def convert(self, source, dest, value):
        if self.is_allowed(source, dest):
            val = getattr(self, '{}_to_{}'.format(source, dest))(value)
            return val
        return None


# note: none of these numbers are `100% accurate or precise`
converter = Convert()
print(converter.convert('pounds', 'kilos', 10.0) == 4.53592)
print(converter.convert('kilos', 'pounds', 10.0) == 22.0462)
print(converter.convert('kilos', 'grams', 10.0) == 10_000)
print(converter.convert('pounds', 'grams', 10.0) == 4535.92)
print(converter.convert('meters', 'feet', 10.0) == 32.8084)
print(converter.convert('feet', 'meters', 10.0) == 3.048)
print(round(converter.convert('farenheit', 'celsius', 10.0), 2) == -12.22)
print(converter.convert('celsius', 'farenheit', 10.0) == 50.0)

volts_to_gigavolts = lambda v: v * 0.000000001
converter.add(volts_to_gigavolts, 'volts', 'gigavolts')
print(converter.convert('volts', 'gigavolts', 100))


maxwells_to_ohms = lambda Convert, e: (e**-e**2) * e**2
converter.add(maxwells_to_ohms, 'maxwells', 'ohms')
print(converter.convert('maxwells', 'ohms', 120))