AppleScript: The Definitive Guide, 2nd Edition

Dereferencing a Reference

Once you have a variable whose value is a reference, AppleScript behaves with confusing inconsistency when you try to use it. In some cases, you can't use the reference unless you explicitly dereference it; in other cases, AppleScript dereferences it for you implicitly when you use it. AppleScript can even behave both ways with one and the same reference.

When AppleScript performs implicit dereferencing , the reference is completely transparent; it acts precisely as if you were saying the incantation that's frozen inside it. This is exactly the same phenomenon noted in the previous section—you can't learn from a reference that it is a reference, because it acts as if it were the thing referred to.

tell application "Finder"
    set x to folder 1
end tell
name of x -- Mannie
class of x -- folder
set name of x to "Moe"

None of that ought to be possible. A reference's class isn't folder, and a reference doesn't have a name property that you can get and set. In this case, though, it happens that the reference is a reference to a thing whose class is folder and that has a name property. AppleScript dereferences the reference implicitly; it treats the reference as if it were the thing referred to.

But in this example, an attempt to use the same reference transparently runs up against a brick wall:

tell application "Finder"
    set x to a reference to name of folder 1
end tell
set x to "Moe"

If you were hoping that this code would set the name of the Finder's folder 1 to "Moe" ...