[R] callback environment for Tk buttons

[Peter Dalgaard BSA]

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")


-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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