Using Tcl's uplevel command to create a static variable control structure

static-variables.tcl

# This is an example of using Tcl's uplevel to create new control structures,
# and can be found on page 59 of "Exploring Expect" by Don Libes.
# Like variables declared global, variables declared static are
# accessible from other procedures. However, the same static variable
# cannot be accessed by procedures in different files.
#
# @param args The aguments to static are the same as global.
# @return Void, the side effect is manipulating the static state array.
proc static {args} {
    set unique [info script]
        foreach var $args {
        uplevel 1 "upvar #0 static($unique:$var) $var"
    }
}