[R] callback environment for Tk buttons

[Luke Tierney]

Peter Dalgaard BSA wrote:
> Luke Tierney <luke at stat.umn.edu> writes:
> 
> > > If I translate this to R, I get:
> > >     tt <- tktoplevel()
> > >     for (i in c("hello", "HALLO"))
> > >         tkpack (tkbutton (tt, text=i,
> > >                           command=function()cat(i,"world\n")), fill="x")
> > >     tkpack (tkbutton (tt, text="dismiss",
> > >                       command=function()tkdestroy(tt)), fill="x")
> 
> > If you don't want to create a function, use local:
> > 
> >      tt <- tktoplevel()
> >      for (i in c("hello", "HALLO"))
> >          local({
> >              j <- i
> >              cb <- eval(substitute(function()cat(w,"world\n"), list(w=j)))
> >              tkpack (tkbutton (tt, text=j, command=cb), fill="x")
> >          })
> >      tkpack (tkbutton (tt, text="dismiss",
> >                        command=function()tkdestroy(tt)), fill="x")
> >  
> 
> Hmm. I thought you didn't want eval(substitute(..))?
> 
> How about 
> 
>     tt <- tktoplevel()
>     for (i in c("hello", "HALLO")) {
> 	cb <- local({i<-i; function()cat(i,"world\n")})
>         tkpack (tkbutton (tt, text=i,
>                           command=cb), fill="x")
>     }
>     tkpack (tkbutton (tt, text="dismiss",
>                       command=function()tkdestroy(tt)), fill="x")
> 
> 

THank you, peter.

That was the fryingpan and the fire of sut and paste. :-)

luke


-- 
Luke Tierney
University of Minnesota                      Phone:           612-625-7843
School of Statistics                         Fax:             612-624-8868
313 Ford Hall, 224 Church St. S.E.           email:      luke at stat.umn.edu
Minneapolis, MN 55455 USA                    WWW:  http://www.stat.umn.edu
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