[R] tcltk table "validateCommand"

peter dalgaard pdalgd at gmail.com
Mon Jan 25 11:21:50 CET 2016

It's been so long that I have forgotten how to get the package with the table widget installed on OSX, so I cannot check things for you. However, the canonical way to handle %S type arguments is to pass them as formal arguments to the callback, e.g.

> .Tcl.callback(function(x,y)x+y)
[1] "R_call 0x7f9a34806ca0 %x %y"

so I would assume that you should just define your 

CellValidation <- function(S){....}

and then just access S as a variable inside the function. 

As far as I remember, this only works at entry completion, though. That does sort of make sense since not every prefix of a valid entry is valid ("1e-2" is a double, "1e-" is not). If you want to actually disable certain keys during entry, then you have a larger task on your hand.


On 22 Jan 2016, at 21:25 , Dalthorp, Daniel <ddalthorp at usgs.gov> wrote:

> I'd like to allow users to edit data in tcltk tables and to use vcmd to
> validate data entry, e.g., not allowing non-numbers to be entered in
> numeric cells and not allowing '\n' to be entered in text cells.
> The problem is that I can't figure out how to "see" their data entry before
> it is entered, although it looks like %S can be somehow used in vcmd to get
> this information.
> Example: to disallow '\n' to be entered into a cell in an editable table:
> require(tcltk2)
> tt<-tktoplevel(); tfr<-tkframe(tt); tkgrid(tfr)
> tableData<-tclArray()
> tableData[[0,0]]<-"junk"
> CellValidation<-function(){
> ## http://www.tcl.tk/community/hobbs/tcl/capp/tkTable/tkTable.html says:
> ## *%S* For *ValidateCommand*, it is the potential new value of the cell
> being validated.
> ## which is exactly what I want, but I can't figure out how to do that.
> ## The following allows one bad character and then disallows further edits
>  testval<-tclvalue(tcl(table1,"curvalue"))
>  if (length(grep("\n",testval))>0)  return(tcl("expr", FALSE))  else
> return(tcl("expr", TRUE))
> }
> table1<<-tk2table(tfr,
>  rows=1,cols=1,
>  selectmode="extended",
>  variable=tableData,
>  validate=T,
>  vcmd=CellValidation
> )
> tcl(table1,"tag","configure", "active", fg='black',bg=colors()[411])
> tkgrid(table1)
> How can I get the %S value rather than the tcl(table1,"curvalue")?
> Much thanks for any help.
> -Dan
> 	[[alternative HTML version deleted]]
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Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd.mes at cbs.dk  Priv: PDalgd at gmail.com

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