example-code-2e/17-it-generator/sentence_genexp.py
2019-04-06 07:11:08 -03:00

45 lines
989 B
Python

"""
Sentence: iterate over words using a generator expression
"""
# BEGIN SENTENCE_GENEXP
import re
import reprlib
RE_WORD = re.compile(r'\w+')
class Sentence:
def __init__(self, text):
self.text = text
def __repr__(self):
return 'Sentence(%s)' % reprlib.repr(self.text)
def __iter__(self):
return (match.group() for match in RE_WORD.finditer(self.text))
# END SENTENCE_GENEXP
def main():
import sys
import warnings
try:
filename = sys.argv[1]
word_number = int(sys.argv[2])
except (IndexError, ValueError):
print('Usage: %s <file-name> <word-number>' % sys.argv[0])
sys.exit(1)
with open(filename, 'rt', encoding='utf-8') as text_file:
s = Sentence(text_file.read())
for n, word in enumerate(s, 1):
if n == word_number:
print(word)
break
else:
warnings.warn('last word is #%d, "%s"' % (n, word))
if __name__ == '__main__':
main()