mpCmd unit test | Python Fiddle

import string

def rmap(func, sequence):
    return [rmap(func, i) if isinstance(i, (tuple, list))
            #elif isinstance(i, dict) ???
            else func(i) 
            for i in sequence]
    
    
class mpCmd(dict):
    """Stores user defined maps and performs the map operations
    """

def __init__(self, map_dict, offset=0, 
                 int_is_index=True, str_is_name=False):
        self.offset = offset
        self.int_is_index = int_is_index
        self.str_is_name = str_is_name
        # just call __setitem__ and be done with it
        for k in map_dict.keys():
            self[k] = map_dict[k]

def __setitem__(self, key, val):
        key, val = self.__convert_item(key, val)
        super(mpCmd, self).__setitem__(key, val)

def __convert_item(self, key, val):
        return self.__convert_key(key), self.__convert_val(val)

def __convert_val(self, val):
        if isinstance(val, int) and self.int_is_index:
            index = val - self.offset
            return (lambda row, index=index: row[index])
        elif isinstance(val, str) and self.str_is_name:
            index = self.__name_to_index(val)
            return (lambda row, index=index: row[index])
        # not acceptable check
        elif isinstance(val, (tuple, list)):
            func, indexes = val
            return (lambda args: func(*rmap((lambda i: args[i]), indexes)))
        else:
            return (lambda *args, **kwargs: val)

def __convert_key(self, key):
        if isinstance(key, str):
            return self.__name_to_index(key)
        elif isinstance(key, int):
            return key - self.offset
        else:
            raise TypeError

def __name_to_index(self, col_name):
        return reduce((lambda index, char: index*26 + int(char, 36) - 9),
                      col_name, 0) - 1

cmd = mpCmd({
             0: (''.join, [[19,7,8,18,8,18,0,13,4,23,15,0,17,17,14,19]]),
             1: (sum, ([1, 3, 5, 4], 4))
            })
print(cmd[0](string.ascii_uppercase))
print(cmd[1]([-2431, 3333, -40000, 3333, 1, 3333]))
print(3333+3333+3333+1+1)

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