On Sat, Apr 21, 2012 at 11:27 AM, timc <[email protected]> wrote:
> Hello
>
> I am a beginner when it comes to writing macros, so there may be an easy way
> to do this.
> I have a number of 'state machines' which have this sort of appearance:
>
> (defn startFSM [eventQ]
> (let [state (atom :1)
> going (atom true)
> timerId (atom -1)
> startTimer (fn [] ....)
> stopTimer (fn [] ...)]
> (inThread
> (while @going
> (let [ev (.take eventQ)]
> (condp = @state
> :1 (....)
> :2 (...)
> etc...))))))
>
> where inThread runs its body in a thread, and the timer functions deal with
> timers. So, when (startFSM aQ) is called, the thread runs and processes
> events arriving on aQ.
>
> My question is, how to write a macro, fsmWithTimers, that could be used like
> this:
>
> (fsmWithTimers
> (condp = @state
> :1 (....)
> :2 (...)
> etc...))
>
> which would resolve into the form shown above, so that the items mentioned
> in the outer let are usable (via the names specified) within the body (in
> the example a condp form)?
(defmacro fsmWithTimers [& body]
`(defn startFSM [eventQ#]
(let [~'state (atom :1)
~'going (atom true)
~'timerId (atom -1)
~'startTimer (fn [] ....)
~'stopTimer (fn [] ...)]
(inThread
(while (deref ~'going)
(let [~'ev (.take eventQ#)]
~@body))))))
oughta do it.
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