Guessing game

David Bovill david.bovill at gmail.com
Tue Apr 3 18:58:21 EDT 2018


Yes - thanks for pointing that out. So far I've found the behaviour of
lockmessages to be actually useful rather than an issue with
getprop/setprop - seems well designed to me.

The place where the syntax really shines is with functions calls rather
than commands - dispatch is quite natural for that. Say you want the model
data of a stack "My Project" - the syntax:

put the project_Data of stack "My Project" into pData


is much more elegant and comprehensible than any way to call a function.
this is also nice:

put the project_Data ["pretty colour"] of stack "My Project" into
> defaultColour




On 3 April 2018 at 18:05, Richard Gaskin via use-livecode <
use-livecode at lists.runrev.com> wrote:

> David Bovill wrote:
>
> > The use-case I had was to replace send syntax with the more elegant
> > set the ... of object to syntax.
>
> While the getProp and setProp handlers would seem to lend themselves to a
> lot of useful object binding opportunities, they require caution: they're
> treated by the engine as system messages, and as such are not immune to the
> effects of lockMessages the way custom handlers are.
>
> Systems depending on getProp and setProp will need to monitor lockMessages
> carefully to insure critical triggers are received as expected.
>
> Using getter and setter accessor handlers avoids that concern, with a
> stylistic difference that isn't much more verbose:
>
>   set the BeautifulColor of cd 1 to "light-grey"
>
> -vs-
>
>   dispatch SetBeautifulColor to cd 1 with "light-grey"
>
> It doesn't read as nicely, but given that the trade-off can be
> unpredictability I'll take what I can get. :)
>
> And depending on usage context, in many cases the UI event that initiates
> a calling chain may be on the card in question, not requiring
> out-of-message-path dispatching, making the call simpler than a property
> setting:
>
>    SetBeautifulColor "light-grey"
>
> For virtual objects like models, accessors can simplify things by not
> requiring that they be bound to a physical object which need not otherwise
> exist.  The name-value-pair programming we enjoy with custom props applies
> equally well with any array.  But with arrays we can have deeper levels,
> and are more easily savable/transportable than an object bound to a stack
> file.
>
> --
>  Richard Gaskin
>  Fourth World Systems
>  Software Design and Development for the Desktop, Mobile, and the Web
>  ____________________________________________________________________
>  Ambassador at FourthWorld.com                http://www.FourthWorld.com
>
>
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