cookbook1.9 简化字符串t'ranslate方法的使用

#-*- coding: utf-8 -*-import stringdef translator(frm='', to='', delete='', keep=None):    if len(to) == 1:        to = to * len(to)    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 translateif '__main__' == __name__:        #选出属于指定集合的字符    print string.digits    digits_only = translator(keep = string.digits)    print digits_only('Chris Perkins:224-7992')        #移除属于某字符集合的元素    no_digits = translator(delete=string.digits)    print no_digits('Eric chen: 1234-5678')          #用某个字符替换属于某指定集合的字符    digits_to_hash = translator(frm=string.digits, to='*')    print digits_to_hash('Eric chen: 1234-5678')