import md5, pickle, random, urllib

def urlencode(arg):
    return urllib.quote(arg, ',-_.~')

urldecode = urllib.unquote

def serialize(args):
    #return pickle.dumps(args).encode('base64').replace('\n', '')
    return ':'.join(map(urlencode, args))

def unserialize(arg):
    #return pickle.loads(arg.decode('base64'))
    return map(urldecode, arg.split(':'))

def sign(arg, salt):
    m = md5.new(salt)
    m.update(':')
    m.update(arg)
    digest = m.digest()
    sig = digest.encode('hex')
    return sig

def validsig(sig, arg, salt):
    return sig == sign(arg, salt)

def genpass(len=8, chars="abcdefghijklmnopqrstuvwxyz0123456789"):
    newpass = []
    for _ in range(len):
        newpass.append(random.choice(chars))
    return ''.join(newpass)

def validnick(name, validchars="abcdefghijklmnopqrstuvwxyz0123456789_-+"):
    if not name:
        return False
    for char in name:
        if not char in validchars:
            return False
    return True

#def cached(fn):
#    cache = [False, ([],{}), None] # called?, (args, kwargs), result
#    def newfunc(*a, **kw):
#        if not (cache[0] and cache[1] == (a, kw)):
#            cache[0] = True
#            cache[1] = (a, kw)
#            cache[2] = fn(*a, **kw)
#        return cache[2]
#    return newfunc