Newbie - Timers and Send

Dar Scott dsc at
Mon Dec 8 22:08:24 CST 2003

On Monday, December 8, 2003, at 03:42 PM, erik hansen wrote:

>> Always go to the clock for accurate
>> timing. adjust the
>> delay specified in the
>> send to target the end of the next period.
> would you have a short example handy?

I looked into the "Primer on Message Mechanics" stack available at my 
web site, but it did not have a complete example.  (See pages on Simple 
Sync, Synchronization and Scheduling for partial info.)

It did mention an intermediate method that I forgot to mention.  In 
many cases you can get much better results by putting the send at the 
top of the handler that is executed repeated rather than at the bottom. 
  There are advantages to putting it at the bottom, but if a better 
timing cycle is desired, the top is better.  This does not apply to the 
example below.

I don't have a short example, but I'll make it up.

This is a variation of "Flasher with Abort and Init" in the "Primer on 
Message Mechanics".  It is untested, so let me know how it works and I 
might put it in the next primer.  It needs this script in the script of 
a graphic (say a circle) and buttons to send initFlashing, 
startFlashing and stopFlashing to the graphic.


constant unlitColor = "100,130,110"
constant litColor  = "255,0,0"

local flashID = ""
local currentColor = "100,130,110"

local flashTimer = ""

on initFlashing
   setColor unlitColor
end initFlashing

on startFlashing
   if flashID is empty then
     send "flash" to me in 0 seconds
     put the result into flashID
     put the long seconds into flashTimer   -- new
   end if
end startFlashing

on stopFlashing
   cancel flashID
   put empty into flashID
end stopFlashing

on flash
     add .4 to flashTimer  -- new
     send "flash" to me in (flashTimer - the long seconds) seconds  -- 
     put the result into flashID
end flash

on toggleColor
   if currentColor is litColor then
     setColor unlitColor
     setColor litColor
   end if
end toggleColor

on setColor theColor
   set the backgroundColor of me to theColor
   put theColor into currentColor
end setColor


Note that in this case, the send is at the end.

Dar Scott

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