On Friday, September 30, 2016 at 7:16:10 PM UTC+1, Les Cargill wrote:
> A really interesting design approach in Tcl is to install a callback
> when a variable is written to. This affords highly event-driven
> programming.
>
> Example ( sorry; it's Tcl ) :
>
>
> namespace eval events {
> set preRPM -1
> proc handleRPM { args } {
> # do stuff to handle an RPM change here
> variable ::motor::RPM
> variable preRPM
> puts "RPM changed from $preRPM to $RPM
> set preRPM $RPM
> }
> }
>
> ...
>
> trace variable ::motor::RPM w ::events::handleRPM
>
> ...
>
> set ::motor::RPM 33.33
>
> What is an equivalent mechanism in Python?
>
> Thanks in advance.
>
> --
> Les Cargill
Perhaps you could pinch the idea, or even the code, from tkinter? E.g. see the
section "Variable tracing" at
http://stupidpythonideas.blogspot.co.uk/2013/12/tkinter-validation.html
Kindest regards.
Mark Lawrence.
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