简化字符串的 translate 方法的使用

import string

def Translator(frm = '', to = '', delete = '', keep = None):
    if len(to) == 1:
        to = to * len(frm)
    trans = string.maketrans(frm, to)
    if keep is not None:
        allchars = string.maketrans('', '')
        delete = allchars.translate(allchars, keep.translate(allchars, delete))
    
    def translate(s):
        return s.translate(trans, delete)
    
    return translate

In [6]: from translator import *

In [7]: digits_only = Translator(keep = string.digits)

In [8]: digits_only('Chris Perkins:224-7992 ')
Out[8]: '2247992'

In [10]: digits_to_hash = Translator(frm = string.digits, to = '#')

In [11]: digits_to_hash('Chris Perkins:224-7992')
Out[11]: 'Chris Perkins:###-####'

来源：Python Cookbook 第2版