[R-gui] Example using 'after'

[Peter Dalgaard]

Paul Roebuck wrote:
> On Fri, 10 Oct 2008, Peter Dalgaard wrote:
> 
>> Paul Roebuck wrote:
>>> Does this work when using tcltk package?
>>> 
>>> I tried the minimalist tcl("after idle bell")
>>> 
>>> but it just gives an error.
>>> 
>>> Does someone have an example?
>>> 
>> tcl("after", "idle", "bell")
>> 
>> or
>> 
>> .Tcl("after idle bell")
>> 
>> (which starts with a dot because you shouldn't have to know about 
>> it....)
>> 
> 
> Thanks for responding. How far does this go? This was a trivial 
> example so I didn't expect much but there appears to be little 
> support for using "after" in general. If I have an actual procedure 
> to call, just write the entire code as a single string and pass it to
>  .Tcl() method?
> 
> For instance, if one wanted to set a minimum size for a Tk 
> application, the Tcl code might be as follows:
> 
> after idle [format { update idletasks wm minsize %s [winfo reqwidth 
> %s] [winfo reqheight %s] } $top $top $top]
> 

You're a bit on your own there, in the sense that I can't afford
spending hours to figure out the exact way of doing it. However, notice
that the general picture is that callbacks can be R functions so it
could be something like

tkafter("idle", function() {
    tkupdate("idletasks")
    tkwm("minsize", tt,
         tkwinfo("regwidth", tt),
         tkwinfo("regheight", tt))
})

(Notice that there are predefined shortcuts

tkwm(....) for

tcl("wm", ...) etc.)

> Also, could you (Peter) clarify whether the environment created with 
> each Tk widget should be considered "private"? In other words, is 
> storing widget-specific user data within its environment 
> user-supported functionality?

They're not intended for that, just to hold widget references and
callback, but I don't see any harm in "abusing" them for other purposes.
The general idea was to use ordinary lexical scoping rules, though.


-- 
    O__  ---- Peter Dalgaard             Øster Farimagsgade 5, Entr.B
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