Machine
Contents
Calling Pattern
Call
local m = sl.machine(a[,b])
Args
a is a table of functions b optional, is a table
Results
m is a machine closure
Closure Methods
Example Usage
local s = {
initiate = function(h,...) local a = {...} print('initiating '..a[1]) return 'a' end,
a = function(h) print('a') return 'b' end,
b = function(h) print('b') return 'c' end,
c = function(h) print('c') return 'exit' end,
exit = function(h) print('exiting') return 999 end,
monitor = function(s,h,n,g) if g=='exit' then h[1]=h[1]+1; if h[1]<3 then g='a' end end; return g end,
}
local h = {0}
local m = sl.machine(s,h)
local n = m.init('live')
print(tostring(n))
--> initiating live
a
b
c
a
b
c
a
b
c
exiting
999
Description
Calling machine returns a state machine closure with one defined method, machine.initiate. The first argument, a, is the table of state functions, and b is an optional table passed to each state function upon transition into its corresponding state. If b isn't provided, then b is set to a newly created empty table.
State Function Prototypes
The state table must provide function values for at least two keys: 'initiate' and 'exit'. The initiate function receives the optional argument b upon initialization (or a newly created empty table if it isn't) as well as any variadic arguments from the machine.initiate call, and should the key representing the next state to transition into.
-- initiate function a.initiate = function(b, ...) return 'c' end
A typical state function receives b as its sole argument, and should return the key representing the next state to transition into.
-- a typical state function a.c = function(b) return 'c' end
The exit function receives b as its sole argument, and its return value will be echoed as the return value of machine.initiate if no errors occur during the execution of the state machine.
-- exit function a.exit = function(b) return r end
If the optional monitor function is provided, it receives as arguments a reference to the state function table, the b table, the last state key l, and the requested transition state key n. Monitor should return the key representing the next state to transition into, either echoing the requested key or overriding it.
-- optional monitor function a.monitor = function(a,b,l,n) return n end
Upon Error
If the described argument pattern isn't matched or the required state keys aren't available, an error is reported and handled according to the operant error redirection mode.
