gistfile1.py

class Script(object):
    "An executable LUA script object returned by ``register_script``"

    def __init__(self, registered_client, script):
        self.registered_client = registered_client
        self.script = script
        self.sha = None

    def __call__(self, keys=[], args=[], client=None):
        "Execute the script, passing any required ``args``"
        client = client or self.registered_client
        args = tuple(keys) + tuple(args)
        if not self.sha:
            self.sha = client.script_load(self.script)
        try:
            return client.evalsha(self.sha, len(keys), *args)
        except NoScriptError:
            # Maybe the client is pointed to a differnet server than the client
            # that created this instance?
            # TODO: Need to account for pipelines since the error won't be
            # caught until the transaction is executed, causing problems
            self.sha = client.script_load(self.script)
            return client.evalsha(self.sha, len(keys), *args)



r = redis.Redis()
r.set('foo', 2)

# Gets the value of 'foo' and multiplies it by the first non-key argument
lua = """
local multiplyer = tonumber(ARGV[1])
local get_value = redis.call('get', KEYS[1])
get_value = tonumber(get_value)
return get_value * multiplyer"""

get_and_multiply = r.register_script(lua, 'foo')

# returns 10
get_and_multiply(r, 5)

# but most of the time, keys will be dynamic. how do we specify dynamic keys? can't do it at function registration time...

get_and_multiply = r.register_script(lua) # no keys specified at compile time
key = 'foo' # assume this is calculated in some way

# Problem here is that we need to tell Redis which argument(s) are keys vs. which arguments are just plan arguments that aren't key names.

# perhaps? seems a bit ugly, but at least works...
get_and_multiply(r, 5, keys=[key])

# alternatively, could optionally tell `register_script` how many of the arguments will be keys...
get_and_multiply = r.register_script(lua, num_keys=1)

# returns 10
get_and_multiply(r, key, 5)