Moving from Microsoft Office VBA to AppleScript:
MacTech's Guide to Making the Transition

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April, 2007
Page 8

end tell

That, of course, is very similar to VBA's With-End With blocks, discussed in more detail below.

Here‘s the place to mention a "gotcha": just sometimes those chains of "ofs" (or apostrophe-s‘s, or tells) don‘t work, for no apparent reason: occasionally the developers have forgotten to implement the "implicit get" and you need to use an "explicit get" for one of the deeper 'of' properties:

tell application "Microsoft Word"

    tell active document

        tell text object

            tell find object

               set content to "blue"

               set forward to true

               execute find

            end tell

        end tell

    end tell

end tell
--> false

whereas:

tell application "Microsoft Word"

    tell active document

        tell text object

            tell (get find object) -- crucial!

               set content to "blue"

               set forward to true

               execute find

            end tell

        end tell

    end tell

end tell
--> true

In most applications, when this happens, the absence of an explicit get, when needed, results in an error: this can be perplexing, but at least you know something is wrong. Here you get an incorrect result, which is worse. But it‘s very rare in Word (more common recently in Entourage, especially among the new Exchange properties, where you‘ll get either an error or missing value as a result, without get.) When in doubt, throw in a get.

One more "gotcha" that scripters familiar with VBA, or just about any language but AppleScript, tend to keep stumbling on, even when they know better: in AppleScript, the = sign is not used as an assignment operator (the implicit Let Method in VBA):

     someVariable = "text"

In AppleScript, the = sign is used only as an equality comparison operator:

   if someVariable = "text" then …

To assign a value to a variable, you must use set…to:

   set someVariable to "text"

Also note that, unlike in VBA, there is no difference in the syntax whether you are assigning a basic type like string or integer to the variable, or an application object: you always use set.

Subs and Handlers

In a VBA macro, every line of code is in a Sub or Function. Even if there‘s only one simple procedure in the macro, it has to be in a named Sub Whatever(). In AppleScript, the equivalent "one simple procedure" is the top-level of the script, not in a handler (subroutine).

Actually, as the AppleScript books will tell you, the top level is an implicit 'run' handler, and you can make it explicit if you want by encasing it all in an on run/end run block. But there‘s almost never a reason for doing so, and almost no one ever does. There is only one rare situation where it is necessary: If you are loading and calling the script from another, external, script and need to pass it arguments. Normally, this would be done by calling a subroutine, but there are some rare circumstances – usually from an application, shell or Internet contexts outside AppleScript itself – that can only run a script, not call individual subroutines.