Talk:Event-driven finite-state machine

Removed text

I removed the following from the article, as it appears to be unencyclopeadic, and/or confusing or strange:

The author of StateCHARTS uses the term event driven finite state machine to describe machines where any incoming input has to be consumed immediately, i.e. the FSM has to perform a transition or input action otherwise the input disappears.

In contrast to the StateCHART virtual finite state machine (VFSM) technology, the application of event driven FSM in complex systems leads to the state explosion problem, as each truly required state path must be repeated for all possible input values. Event driven FSM can be implemented with a state transition table as is often done for parser applications.

A significant reduction in complexity can be achieved by utilizing hierarchy a la hierarchical state machines (HSMs). The use of hierarchy eliminates the "state explosion" problem by allowing a single transition from multiple related states, through state nesting. A more rigorous definition of hierarchical state machines that includes an example can be found at http://www.quantum-leaps.com/resources/glossary.htm#HSM.

Possibly cite http://www.programmersheaven.com/2/Design-State-Machine-Engine (an example of someone speaking about event-driven state machines as an informal idiom)

Please don't re-insert without review. linas 21:40, 29 May 2007 (UTC)[reply]

Bug in program

There's a bug in this program as state_init == state_red, but there's separate STATE_INIT and STATE_RED states, so red will initially be on for 60 secs, not 30. Genjix (talk) 03:24, 17 March 2008 (UTC)[reply]

Possible bug in program

The variable 'operation' is set to 1 at the beginning of the program, and never changed afterwards. Hard to see what the point is.

Controversiality

Why isn't there any discussion of why state machines could be a bad idea? This code could be a million times clearer if it was allowed to explicitly pend on events. —Preceding unsigned comment added by 216.31.211.11 (talk) 00:03, 11 September 2008 (UTC)[reply]

Because in places they're used, at any particular time the object must be able to respond to any one of several possible events which could happen. For instance, a traffic light that normally switches based on a timer could have an input that's switched by an emergency vehicle. This would alter the pattern to give the vehicle right of way when it is detected. The code can't be looping just looking at the timer when it needs to also respond to the emergency vehicle switch.--71.214.211.129 (talk) 17:02, 18 September 2010 (UTC)[reply]

The example code is a FSM, but the style is very bad.

Any FSM (so the fucntion with that name) shoud do 2 things:

Set/compute (or at least return) the next state
Execute a (list of) actions.

Why does this example do onnly halve of it (and other parts somewhere else? —Preceding unsigned comment added by 62.177.151.49 (talk) 11:36, 1 October 2008 (UTC)[reply]