When is message passing required?

[Mike Kerner]

Paul - as a followup to that, do you understand the difference between
"pass" and "send"?  If you want only the engine, or some other component to
handle a message, you would "send" it.  If you want a handler to let a
message continue up the chain so that another handler can deal with it, you
can "pass" it.

If you want fine-grained control, make sure you understand the position of
your handler in the path, especially with front and backscripts also
getting a voice.

On Mon, May 23, 2016 at 10:35 AM, Mike Kerner <MikeKerner at roadrunner.com>
wrote:

> You only need to pass a message if you don't want another handler for that
> message to possibly get in the way.  If you don't have a keyDown handler in
> any of your scripts in the message path, the engine will get and handle it.
>
> On Mon, May 23, 2016 at 9:13 AM, Paul Dupuis <paul at researchware.com>
> wrote:
>
>> In LiveCode some messages must be passed to the engine for the engine's
>> normal processing of the message. And with current versions of LC you
>> have the very handy 'pass <message> to top' to send it directly to the
>> engine.
>>
>> For example, rawkeyDown must be passed for LiveCode to handle key
>> presses other than what you are trapping (unless you want all keypresses
>> trapped). Some message line preOpenStack you don't need to pass. The
>> stack still opens without passing a preOpenStack to the the engine.
>>
>> Does anyone have a compiled list of which messages need to be passed or
>> *should* be passed vs those that you do not have to concern yourself with?
>>
>> In some dictionary entries, like for rawKeyDown, it talks about the need
>> to pass the message (unless you want to trap all key presses). In other
>> dictionary entries it is not clear whether the message needs to be
>> passed or not. I am not sure that if it doesn't state one way or another
>> assuming one way or another is wise.
>>
>> I know there have been some excellent flow charts of LiveCode's message
>> passing hierarchy (Richard Gaskin's comes to mind) but I don't recall
>> seeing any summation of which messages should be passed vs which do not
>> need to be?
>>
>>
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>
>
>
> --
> On the first day, God created the heavens and the Earth
> On the second day, God created the oceans.
> On the third day, God put the animals on hold for a few hours,
>    and did a little diving.
> And God said, "This is good."
>



-- 
On the first day, God created the heavens and the Earth
On the second day, God created the oceans.
On the third day, God put the animals on hold for a few hours,
   and did a little diving.
And God said, "This is good."