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"