Some people have been asking (on news:comp.lang.tcl ) for the Tk core to be modified so that widgets all carry with them some additional user data. This is not necessary. The following script illustrates how you can do this without all that paraphanalia in pure Tcl...
proc substvars {varlist script} {
foreach varname $varlist {
upvar $varname var
regsub -all %%${varname}%% $script [list $var] script
}
return $script
}
foreach class {
button checkbutton radiobutton menubutton menu label message
frame toplevel scrollbar scale text canvas
} {
rename $class userdata'enabled'$class
proc $class {pathname args} [substvars class {
set class %%class%%
set w [eval [list userdata'enabled'$class $pathname] $args]
rename $w userdata'enabled'$w
upvar #0 ::userdata'data ary
set ary($w) {}
proc $w {subcommand args} [substvars w {
set w %%w%%
if {![string compare $subcommand "setUserData"]} {
upvar #0 ::userdata'data ary
switch [llength $args] {
0 {
return $ary($w)
}
1 {
set ary($w) [lindex $args 0]
return
}
default {
return -code error "wrong # args: should be\
\"$w setUserData ?value?\""
}
}
} else {
return [uplevel userdata'enabled'$w $subcommand $args]
}
}]
return $w
}]
}I'll leave adding the finishing flourishes (like making the error messages take account of the new command, and deleting the user data and the proc when the widget is destroyed) up to others for now. DKF