caller proc

# Returns a fully-qualified name of the command that has invoked
# the caller of this procedure.
# To put is simple: if ::one::bar has invoked ::two::foo, the
# ::two::foo proc can use [caller] to know that its caller
# is ::one::bar
# If the caller of this proc has no caller (i.e. it was called
# on level 0), this proc returns empty string.
# You can specify 2, 3, etc as the argument to get info about
# the caller of the caller and so on (think of [uplevel]).

proc caller {{level 1}} {
    incr level
    if {[catch {info level -$level} prc]} {
	return ""
    } else {
	return [namespace which -command [lindex $prc 0]]
    }
}