Richard Suchenwirth 2002-08-17 - The BWidget package is a set of powerful megawidgets written in pure Tcl. Examination of the source code shows that it is easy to add functionality which can be called in Tk's object-oriented way: if you provide a proc Class::command, where class is one of BWidget's widget classes, calls to a widget of that class with that command will be dispatched to your "method", e.g.
proc Foo::grill {w ...} {...}
Foo .bar
.bar grill args ;# calls Foo::grill .bar argsI employ this simple protocol to extend ComboBoxes for two typical use cases (to appear in starDOM):
}
package require BWidget
namespace eval ComboBox {#needed to extend BWidget functionality}
proc ComboBox::enable {w what args} {
switch -- $what {
history {
$w configure -values {{}} ;# always keep a blank on top
foreach evt {<Return> <FocusOut>} {
$w bind $evt {+ ComboBox::_add %W [%W cget -text]}
}
}
chooser {
set values [$w cget -values]
set width 0
foreach i $values {
set sl [string length $i]
if {$sl > $width} {set width $sl}
}
$w setvalue first
$w configure -width [expr {$width+1}]
$w configure -editable 0 -relief flat -entrybg grey
}
}
if {$args != ""} {eval [list $w configure] $args}
}
# This "internal" function is underscore-prefixed:
proc ComboBox::_add {w item} {
set w [winfo parent $w] ;# binding comes from entry
set values [$w cget -values]
if {[lsearch -exact $values $item] < 0} {
$w configure -values [linsert $values 1 $item]
}
}
#------------------------------------------- Test and demo code:
if {[file tail [info script]]==[file tail $argv0]} {
ComboBox .c -label "Search " -textvariable query
.c bind <Return> {puts [list search -$mode $query]}
.c enable history
ComboBox .m -values {case nocase regexp XPath} -textvariable mode
.m enable chooser
pack .c .m -side left
bind . <Escape> {exec wish $argv0 &; exit}
bind . ? {console show}
}