【python练习】《learn python the hard way》ex41 opp_test.py

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和上一篇一样，这个也加上了中文注释。

# -*- coding: utf-8 -*-
# Copyright by XD 
# 交流QQ:584927688 ^_^
#《learnpythonthehardway》ex41,学会说面向对象。
#oop_test.py
#
#此为learnpythonthehardway中作者为了帮助读者熟悉面向对面的编程\
#而设计的一个根据代码写描述或根据描述写代码的考试小程序。
#

#目的：一方面是督促我自己充分理解这段代码，另一方面也能帮助初学者理解。
import random
from urllib import urlopen
import sys
#作者随意准备的词汇。
WORD_URL = "http://learncodethehardway.org/words.txt"
WORDS = []

#代码及描述中的‘函数方法/属性’function/attribute，‘参数’parameters,‘类名’,‘实例名/对象’，
PHRASES = {
	"class %%%(%%%):":
	"Make a class named %%% that is-a %%%",
	"class %%%(object):\n\tdef __init__(self,***)":
	"class %%% has-a __init__ that takes self and *** parameters.",
	"*** = %%%()":
	"Set *** to an instance of class %%%.",
	"***.***(@@@)":
	"From *** get the *** function, and call it with parameters self,@@@.",
	"***.*** = '***'":
	"From *** get the *** attribute and set it to '***'."
}

# do they want to drill phrases first 
#由答题者选择是要根据描述编码还是根据代码描述。
#sys.argv为从命令行接收的参数，第一个参数默认为文件名。
if len(sys.argv) == 2 and sys.argv[1] == "english":
	PHRASE_FIRST = True
else:
	PHRASE_FIRST = False

# load up the words from the website
#将词汇们载入到列表WORDS中。
for word in urlopen(WORD_URL).readlines():
	WORDS.append(word.strip())

#定义覆盖描述及代码中预留位置的函数，参数为片段、描述。
#最后返回一个列表results
#先将预留放置词汇的位置分类
#参数为key或value，两个总是相对
def convert(snippet, phrase):

	class_names = [w.capitalize() for w in random.sample(WORDS,snippet.count("%%%"))]
	other_names = random.sample(WORDS, snippet.count('***'))
	results = []
	param_names = []

	for i in range(0,snippet.count('@@@')):
		#参数的个数为1-3个随机。
		param_count = random.randint(1,3)
		#随机到几个参数就从WORDS中获取几个词
		param_names.append(', '.join(random.sample(WORDS, param_count)))

	#准备好要进行替换的PHRASES
	for sentence in snippet,phrase:
		result = sentence[:]
		#result = [snippet,phrase]
		#扯句闲话，作者为了描述和代码对应，替换词汇的顺序是固定的。。
		#用这种方法替换，描述与代码中词汇的顺序肯定是一样的。
		#fake class names 类名
		for word in class_names:
			result = result.replace("%%%", word,1)#最后一位参数规定每次替换一个，保证%%%不重复。

		#fake other names 对象、方法和其他
		for word in other_names:
			result = result.replace("***", word,1)

		#fake parameter lists 参数名
		for word in param_names:
			result = result.replace("@@@",word,1)

		results.append(result)

	return results

# keep going until they hit CTRL-D
#这里才是重点，是作者的编程逻辑。
try:
	while True:#循环抽题
		snippets = PHRASES.keys()
		random.shuffle(snippets)#随机打乱顺序

		for snippet in snippets:#抽题
			phrase = PHRASES[snippet]
			question, answer = convert(snippet, phrase)
			if PHRASE_FIRST:
				question, answer =answer, question

			print question

			raw_input(" >")
		print "ANSWER: %s\n\n" % answer
except EOFError:
	print '\nBye!'