entryGuard and exitGuard.

[shabaka101694]

Good morning.
I am trying to figure out hoe entryGuard() and exitGuard() work in the HFSM2 framework.
In other frameworks, typically, the guard methods have a return type of bool. If the guard method returns true then the guard condition is satisfied and the transition will occur. It appears that in HFSM2 the signature for entryGuard is
void entryGuard(GuardControl&)

I only saw one example that uses the entryGuard ( debug_logger_interface) - and in this example the guard is not used.
Could some guidance/an example be given on use of entryGuard() and exitGuard() methods.
(it seems ??) that this same functionality could be accomplished by setting variables in the Context but this seems hackish

Thanks
Victor

[andrew-gresyk]

Hi,
There are nine tests demonstrating various bits of entryGuard() functionality, most importantly test_guards.

During a transition processing:

• exit guards are called on states to be deactivated, and
• entry guards are called on the states to be activated

.. before a transition is finalized.

If at least one guard calls GuardControl::cancelPendingTransitions(), the transition is cancelled.

Guards may also initiate other transitions using the usual methods e.g. GuardControl::changeTo(), GuardControl::restart(), etc.
In this case the original transition is substituted with the new one and the processing step repeats from the start up to the number of times set via hfsm2::Config::SubstitutionLimitN<> (4 by default).

There are several methods on GuardControl available for introspection of the FSM, e.g. isActive(), activeSubState(), isPendingEnter(), isPendingChange(), isPendingExit(), etc.

Hope this helps!