Listbox in tk/tcl

Question

Help me please to decide problem with listbox in TCL. I created the next listbox:

listbox .lb1 -height 6 -width 10 -selectmode browse
.lb1 insert 0 "String 1" "String 2" "String 3" "String 4" "String 5" "String  6"

label .label1 -text [.lb1 get active]
button .butt1 -text "enter" -command {.label1 configure -text [.lb1 get active]}
pack .label1 .lb1 .butt1 -expand yes -fill both

How I can change automatically contents of label "label1" without use button "butt1" ?

I want the contents of "label1" will change immediately when I click on one of the list items.

Thanks!

Donal Fellows · Accepted Answer · 2016-01-06 15:58:16Z

3

When you select an item in the listbox, it sends the <<ListboxSelect>> to itself. You can bind to this to react to selection changes:

bind .lb1 <<ListboxSelect>> {.label1 configure -text [.lb1 get active]}

Note that you're also getting very close to the point where using a helper procedure is advised. Even for something simple like this, it makes things easier to write, test and debug.

proc SelectionHappened {listbox label} {
    set activeItem [$listbox get active]
    $label configure -text $activeItem
}
bind .lb1 <<ListboxSelect>> {SelectionHappened .lb1 .label1}

answered Jan 6, 2016 at 15:58

Donal Fellows

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