笨办法学习python-ex41源码加自己注释

#!/user/bin/env python
#-*-coding:utf-8 -*-
#Author: qinjiaxi
import random
from urllib import urlopen
import sys
WORD_URL = "http://learncodethehardway.org/words.txt"
WORDS =[]
PHRASES = {
    "class ###(###):":
    "Make a class named ### that is-a ###.",
    "class ###(object):
	def __init__(self, ***)":
    "class has-a __init__that takes self and *** parameters.",
    "class ###(object):
	def ***(self, @@@)":
    "class ### has-a function named *** 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
PHRASES_FIRST = False
if len(sys.argv) == 2 and sys.argv[1] == 'english':
    PHRASES_FIRST = True
#load up the words from the website
for word in urlopen(WORD_URL).readlines():
    WORDS.append(word.strip())

def convert(snippet, phrase):
    class_names = [w.capitalize() for w in
                random.sample(WORDS, snippet.count('###'))]#从words序列中抽取带'###'的字符串，数量是片段里面含有'###'的数量并把第一个字母变大写，后面变小些(也就是随机抽取类)
    other_names = random.sample(WORDS, snippet.count("***"))#从words序列中抽取带'***'的字符串,数量是片段里面含有'***'的数量
    results = []
    param_names = []
    for i in range(0, snippet.count('@@@')):
        param_count = random.randint(1, 3)#返回随机个数
        param_names.append(','.join(random.sample(WORDS, param_count)))#从words列表中随机抽取1-3个参数，加入到参数名列表中并用逗号隔开
    for sentence in snippet, phrase:
        result = sentence[:]
        #fake class_names
        for word in class_names:
            result = result.replace("###", word, 1)#把第一个'###'替换成word
        #fake other_names
        for word in sentence:
            result = result.replace("***", word, 1)#把第一个'***'替换成word
        #fake parameter lists
        for word in param_names:
            result = result.replace('@@@', word, 1)#把第一个'@@@'替换成word
        results.append(result)
    return results


try:
    while True:
        snippets = PHRASES.keys()#获取字典中的key并以列表方式返回
        random.shuffle(snippets)#将列表中的元素随机打乱

        for snippet in snippets:
            phrase = PHRASES[snippet]#获取字典中的值
            question, answer = convert(snippet, phrase)#调用convert函数
            if PHRASES_FIRST:
                question, answer = answer, question
                print(question)
                raw_input('>')
                print("ANSWER: %s

" % answer)
except EOFError:
    print('
bye')