WJG (1st September 2005) There's probably something described in the small print of the Tcl man pages that will do something similar but... If I add new functionality to an app I like to pack buttons 'n' stuff on the fly in which case there is no guarentee as to what a widget name might be. Widget bindings allow us to know which item was clicked although the button -command switch has no such choice. To cross this gap we have to work with references. Because the 'bind all' take presidence over the individual button command we can use a binding to set a global variable which subsequent commands can access.
The following code example allows us to create buttons and then allows the button command to make adjustments to itself.
#----------------------------------------------------------------
# whoami.tcl
#----------------------------------------------------------------
#
# Making a button aware of just who it is.
# This can be useful if wigets are built proceedurally and pathnames
# are not defined explicitly.
#
#----------------------------------------------------------------
# set global array for where the last 2 B1 events occured
array set ::widget {
active ""
last ""
}
bind all <Button-1> {
set ::widget(last) $::widget(active)
set ::widget(active) %W
}
#----------------------------------------------------------------
proc whoami {} {
if {[$::widget(active) cget -text] == "Clickme!"} {
$::widget(active) config -text "Clicked!"
} else {
$::widget(active) config -text "Clickme!"
}
puts "I am \"[winfo name ${::widget(active)}]\" and I live in \"[winfo parent ${::widget(active)}]\"."
}
#----------------------------------------------------------------
console show
expr srand(1)
set base .t2
toplevel $base
button .b1 -text Clickme! -command {
whoami
# use randomly created path names
set i [string trimleft [expr rand()] 0.]
pack [button $base.b$i -text "Button $i" -command whoami]
}
pack .b1
bind .b1 <Button-1> {puts "I am %W -hello from my unique <B1> binding."}