REBOL [
    Title:      "Automatic local variables"
    Date:       20-Jul-1999
    File:       %protect-func.r
    Version:    1.0
    Author:     "Thomas Jensen"
    Email:      dm98411@edb.tietgen.dk
    Tabs:       4
    Language:   'English
    Charset:    'ANSI
    Purpose: {
        Function generator that automatically makes local variables
    }
    Category:   [script 3]
]

protected-function: function [spec body] [ locals ][
    locals: make block! []
    foreach word body [
        if set-word? :word [
            append locals make word! :word
        ]
    ]
    function spec locals body
]

example: [
    some-math-function: protected-function [x] [
        y: + x 2
        z: / x 2
        z + y
    ]
    
    x: "this string (x) has not been modified!"
    y: "this string (y) has not been modified!"
    z: "this string (z) has not been modified!"

    print some-math-function 4
    
    print [x newline y newline z]
]
do example