AppleScript: The Definitive Guide, 2nd Edition

12.7. Creating References to Variables

You can't make a reference to a local variable. Well, you can, but if you try to use it you'll get a mysterious error. For example:

local x set x to {1, 2, 3} set y to a reference to x get item 1 of y -- error: Can't make item 1 of x into type reference

But a reference can itself be stored in a local variable:

local y set x to {1, 2, 3} set y to a reference to x get item 1 of y -- 1

You can make a reference to anything that isn't a local, such as a global or a top-level entity:

script myScript property x : 5 set y to a reference to x set contents of y to y + 1 display dialog x end script run myScript -- 6

That works just as well from outside of the script object:

script myScript property x : 5 display dialog x end script tell myScript set y to a reference to its x set contents of y to y + 1 run -- 6 end tell