Currency conversion.

oer.py

#! /usr/bin/python

import urllib2
import json
import time
import sys

baseurl = "http://openexchangerates.org/api/latest.json"
key = "{{Your Open Exchange Rates App ID here!}}"
url = baseurl + "?app_id=" + key

try:
    f = open("latest.json", "r")
    exists = True
except IOError:
    exists = False
except:
    raise

valid = False
if exists:
    raw = f.read()
    data = json.loads(raw)
    f.close()
    if time.time() - data['timestamp'] < 3600:
        valid = True
if not exists or not valid:
    f = open("latest.json", "w")
    s = urllib2.urlopen(url)
    raw = s.read()
    f.write(raw)
    s.close()
    f.close()
    data = json.loads(raw)

if len(sys.argv) != 4:
    print "usage: oer.py from to value"
else:
    base, quotes, value = sys.argv[1:]
    for quote in quotes.split(','):
        result = float(value) * float(data['rates'][quote]) / float(data['rates'][base])
        print "%.4f %s = %.4f %s" % (float(value), base, result, quote)
    print time.strftime("Last update: %c.", time.localtime(int(data['timestamp'])))