On Mon, Jan 21, 2013 at 3:48 PM, Markus Klotzbuecher <
markus [dot] klotzbuecher [..] ...> wrote:

> On Mon, Jan 21, 2013 at 03:09:56PM +0100, Bert Willaert wrote:
> >
> > Hi,
> >
> > I am trying to use as a guard for an rFSM transition a function that I
> define
> > in the ConfigureHook of the component that loads the statemachine.
> >
> > When I put the function directly in the rfsm file it works fine:
> >
> > trans {src="NotAllReady", tgt="AllReady",
> > guard= function()
> > for i=1,n_agents,1 do
> > if get_agent_state(i) ~= "root.Ready" then return false
> end
> > end
> > return true
> > end
> > },
> >
> > But when I do:
> >
> > trans {src="NotAllReady", tgt="AllReady",
> > guard=all_agents_ready()
> > },
>
> You are assigning the return value of calling all_agents_ready() to
> the guard. Unless all_agents_ready happens to generate a guard
> function, this should probably be
>
> guard=all_agents_ready,
>

Ok, I see. After changing this, there is no more error given.

>
>
> > With in the ConfigureHook:
> >
> > all_agents_ready=function()
> > for i=1,n_agents,1 do
> > if get_agent_state(i) ~= "root.Ready" then return false end
> > end
> > return true
> > end
> >
> > I get the following error:
> > 0.394 [ ERROR ][ScriptingService] LuaComponent 'Coordinator': error
> calling
> > function configureHook: fsm_coordinator.lua:39: attempt to call global
> > 'all_agents_ready' (a nil value)
>
> I suppose you get this error because you are calling the guard above,
> but your configureHook has not executed, so the function is not
> defined yet. So even if you follow my above suggestion, you still need
> to ensure that all_agents_ready is defined before you define or load
> the fsm. You can achieve that by means of a forward declaration of
> all_agents_ready somewhere at the top of your Lua component:
>
> all_agents_ready=false
>
> or
>
> all_agents_ready=function() error("redefined in configureHook") end
>
> to get an error in case the function is called.
>

Hmm,

Forward declaration seems to help only when I put the full function
definition before:

fsm = rfsm.init(rfsm.load("Coordinator/fsm_coordinator.lua"))

In the other case, i.e. without forward declaration or with
all_agents_ready=false, the transition happens 'each time' while it
shouldn't ???

>
> > This same function does work fine as entry, doo or exit function. So why
> not as
> > guard? Is this a bug or is there a reason for that?
>

So far, I haven't done forward declaration of functions used in the entry,
exit or doo function and I never got trouble with it.
Is it needed here, and not in the other cases, because you assign to the
value guard actually the function itself,
while in a enty function for example you are only interested in the return
value?

>
> Markus
>
>
>