使用文件进行优化

#函数也是对象，将函数赋值给变量rule,使用rule接收参数，调用函数

#coding:utf-8
import re
import string

'''
rule.en内容：
[szx]$             $     es
[^aeioudgkprt]h$   $     es
[^aeiou]y$         y$    ies
$                  $      $

'''
def buildRule((pattern,search,replace)):
    return lambda word:re.search(pattern,word) and re.sub(search,replace,word)

def plural(noun,language='en'):
    lines = file('rules.%s' % language).readlines()
    patterns = map(string.split,lines)
    rules = map(buildRule,patterns)
    #函数也是对象，将函数赋值给变量rule,使用rule接收参数，调用函数
    for rule in rules:
        result = rule(noun)
        if rusult:
            return result


if __name__ == '__main__':
    plural(noun)

使用生成器：

#coding:utf-8

import re

#rules()函数返回一个生成器对象
def rules(language):
    for line in file(r'rules.%s'%language):
        pattern,search,replace=line.split()
        yield lambda word:re.search(pattern,word) and re.sub(search,replace,word)

def plural(noun,language='en'):
    for applyRule in rules(language):
        #返回的applyRule匿名函数也是一个对象，该对象接收参数，并进行函数调用
        result = applyRule(noun)
        if result:
            return result
if __name__ == '__main__':
    plural(noun)