################################################################ # proc nextFibonacci {}-- # Add one to the global variable var # Arguments # NONE # # Results # global var is modified # proc nextFibonacci {} { # var exists in global scope global var fib1 fib2 set var [expr {$fib1 + $fib2}] set fib1 $fib2 set fib2 $var } set var 1 set fib1 1 set fib2 1 label .l1 -textvar var button .b1 -text "Incr" -command nextFibonacci grid .l1 grid .b1