[R-gui] Tcl/Tk Binding % Substitutions.for Callbacks

Adrian Waddell adrian at waddell.ch
Wed Feb 23 21:00:53 CET 2011


Paul:

On 02/23/2011 02:49 PM, Roebuck,Paul L wrote:
> <previously misfiled in r-devel...>
> 
> How are % substitutions handled for callbacks in R?
> Is there an 'event' parameter that can be requested
> which would contain the rest of the information specific
> to the event type itself?
> 
> How should we translate something like the following:
> 
> Tcl> bind Frame <Enter> {%W config -bg red}
> Tcl> bind Frame <Leave> {%W config -bg white}
> 
> such that the widget id (and other % substitutions) can be accessed
> in R callback? I'm trying to write callback handlers for dynamic
> bindtags.
> 
> one   <- tkframe(width=30, height=30)
> two   <- tkframe(width=30, height=30)
> three <- tkframe(width=30, height=30)
> tkbind("Frame",
>        "<Enter>",
>        function(TBD} {
>            ## How do I determine widget id (%W) here?
>        })

I think you can just use the letter without % as a function argument, try

library(tcltk)
tt <- tktoplevel()
tkbind(tt,'<Enter>',function(W){
  cat(paste('Toplevel',W,'\n'))
})

Greetings,

Adrian


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