Pythonのお勉強 Part4

Asahi.com から円相場の情報を取ってくるサンプルプログラムを書いてみた。
記法は今風にしてみた。要 Python 2.3。

# -*- coding: EUC-JP -*-

import codecs, re, sys, urllib

# Expected page structure:
# <a href="/business/">円相場　108円42銭　(18:39)</a>
PATTERN = u'<a href="/business/">円相場　'
re_yen = re.compile(ur"(\d+)円(\d+)銭　\((\d\d):(\d\d)\)")

Reader = codecs.getreader("EUC-JP")
urlopener = urllib.FancyURLopener()
urlopener.addheader("Pragma", "no-cache")
file = Reader(urlopener.open("http://www.asahi.com/";))
for line in file:
 pos = line.find(PATTERN)
 if pos < 0:
 continue
 match = re_yen.match(line, pos + len(PATTERN))
 if not match:
 raise RuntimeError, "unexpected page structure"
 output = u"%s時%s分現在の円相場は%s円%s銭です。\n" % (
 match.group(3), match.group(4),
 match.group(1), match.group(2))
 sys.stdout.write(output.encode("EUC-JP")) # environment dependent
 break
else:
 raise RuntimeError, "unexpected end of file"
file.close()