Question

Minimal example is really the 2nd example from Rings main page

require"rings"

local init_cmd = [[
require"stable"]]

local count_cmd = [[
count = stable.get"shared_counter" or 0
stable.set ("shared_counter", count + 1)
return count
]]

S = rings.new () -- new state
assert(S:dostring (init_cmd))
print (S:dostring (count_cmd)) -- true, 0
print (S:dostring (count_cmd)) -- true, 1
S:close ()

S = rings.new () -- another new state
assert (S:dostring (init_cmd))
print (S:dostring (count_cmd)) -- true, 2
S:close ()

However, I’m not able to get value of shared_counter. print(shared_counter) outputs nil.

I’ve tried to use stable.get(), but it says stable can only be used in slave states.
I finally tried

remotedostring("shared_counter = "..count)

Which worked, but I’m not quite sure if it’s a proper way to do it. I guess direct access to stable value table would be sufficent?

EDIT: Oh, and I forgot to add, that the main part of the problem is communicating in the other way – from master to slave.

Answer 1

The stable library stores the values in a global table in the master state called _state_persistent_table_. Though obviously this is meant to be hidden and private.

If you’re uncomfortable with this, stable just uses remotedostring() internally, and it would not be hard to do something like that yourself.

For master->slave, slave:dostring() should suffice, using similar techniques.