Learn Python The Hard Way ex41中的程序

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):\n\tdef __init__(self, ***)":
        "class %%% has-a __init__ that takes self and *** parameters.",
    "class %%%(object):\n\tdef ***(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
PHRASE_FIRST = False
if  len(sys.argv) == 2 and sys.argv[1] == "english":
        PHRASE_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("%%%"))]
    other_names = random.sample(WORDS, snippet.count("***"))
    results = []
    param_names = []
    
    for i in range(0, snippet.count("@@@")):
        param_count = random.randint(1,3)
        param_names.append(', '.join(random.sample(WORDS, param_count)))
        
    for sentence in snippet, phrase:
        result = sentence[:]
        
        #fake class names
        for word in class_names:
            result = result.replace("%%%",word,1)
        
        #fake other_names
        for word in other_names:
            result = result.replace("***", word, 1)
            
        #fake parameter lists
        for word in param_names:
            result = result.replace("@@@", word, 1)
            
        results.append(result)
        
    return results
        
# keep going until they hit CTRL-D
try:
    while True:
        snippets = PHRASES.keys()
        random.shuffle(snippets)
        
        for snippet in snippets:
            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"

这个程序的作用是在网一个网址获取一些单词，用这些单词命名程序的代码块和其中的元素。不管你在>后输入什么，程序都会将该代码块的含义及作用打印出来。

当你按Ctrl+Z的时候，程序退出并打印Bye

运行如下：