lexfiend 13 Dec 2005: After noticing at least one request along the lines of "[event generate] without Tk", I decided to hack the following, which is almost-but-not-quite-like trigger:
namespace eval notify {
namespace export register deregister trigger
array set narray {}
proc register {name proc} {
variable narray
set narray(${name}_proc) $proc
trace add variable narray($name) write ::notify::process_trigger
}
proc deregister {name} {
variable narray
if {[array names narray ${name}_proc] != ""} {
trace remove variable narray($name) write ::notify::process_trigger
array unset narray(${name}_proc)
array unset narray(${name})
}
}
proc process_trigger {narray name op} {
after 1 [list eval $::notify::narray(${name}_proc) $::notify::narray(${name})]
}
proc trigger {name args} {
variable narray
set narray(${name}) $args
}
}
proc test_print {arg1 args} {
puts stderr "arg1 = $arg1"
puts stderr "args = $args"
}
proc test_notify {} {
notify::register !test1 test_print
notify::trigger !test1 "This is" a test
notify::trigger !test1 "This is" another test
notify::deregister !test1
notify::trigger !test1 "This should" not fire
}
after idle test_notify
after 1000 {set ::forever 1}
vwait foreverNo warranties, and I'm sure it can be improved.
(As luck would have it, after I hacked the above up, I found The observer design pattern. Marco's implementation is certainly more elegant and can handle multiple registered procedures per trigger, but doesn't actually use the event queue as such.)