Re: [Xotcl] Linking object instance variables to a widget -textvariable?

Hi Ken,

perhaps others use other styles, but a simple way to bind variables,commands, or other callbacks from TK into XOTcl is replacement of "self" (or "my") from within a XOTcl method. Example:

Class BrowserTree BrowserTree instproc init args { ... set tree [Tree $sw.tree \ -relief flat -borderwidth 0 -width 15 -highlightthickness 0\ -redraw 0 -dropenabled 1 -dragenabled 1 \ -dragevent 3 \ -droptypes { TREE_NODE {copy {} move {} link {}} LISTBOX_ITEM {copy {} move {} link {}} } \ -opencmd "[self] modifyTree 1 $sw.tree" \ -closecmd "[self] modifyTree 0 $sw.tree"] ... $tree bindText <ButtonPress-1> "[self] selectTreeElement $tree" $tree bindText <Double-ButtonPress-1> "[self] openTreeElement $tree" ... }

note that you cannot use curly brackets {} here, because then self would not be replaced within the object's scope and would likely have a wrong value or raise an exception.

this style of binding works nicely together with XOTcl's inheritance and mixins

Uwe

On Saturday 15 November 2003 00:04, Ken Jones wrote:

Hi. I've just starting tinkering around with XOTcl the past few days, trying to add it to my repertoire of Tcl OO extensions. It's definitely quite an interesting contrast to others like [incr Tcl] or Snit. While I won't be abandoning either of those, XOTcl is currently my leading candidate for a project I'm likely to be working on through the rest of the year, in large part because of its mixin support.

But one issue I couldn't figure out from my reading of the documentation or examples is whether it's possible to use an object's instance variable as a widget's -textvariable or -listvariable. For example, [incr Tcl] supports the [itcl::scope] command, so I can do something like this:

package require Itcl

::itcl::class Toggle {

private variable _state "normal"

constructor {} {
    checkbutton .cb -text Enable \
        -variable [::itcl::scope _state] \
        -onvalue "normal" -offvalue "disabled" \
        -command [::itcl::code $this toggle]
    .cb select  ;# The checkbutton is initially on

    # ...
}

private method toggle {} {
    # ...
}

}

Is there a similar feature for XOTcl?

Thanks,

• Ken Jones

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