Language Guide

CHAPTER 7

Control Statements

208 Try Statements

offendingObjectVariable (an identiﬁer) is a parameter variable for the reference

to the application or object that caused the error (a reference). You use this

parameter variable to refer to the object that caused the error within the

error handler.

resultListVariable (an identiﬁer) is a parameter variable for the results for objects

that were handled before the error occurred. Its value is a list that can contain

values of any class. You use this parameter variable to refer to the partial

results within the error handler. This parameter applies only to commands that

return results for multiple objects. For example, if an application handles the

command get words 1 thru 5 and an error occurs when handling word 4,

the partial result parameter contains the results for the ﬁrst three words.

expectedTypeVariable (an identiﬁer) is a parameter variable for the expected

value class (a class identiﬁer)—that is, the value class to which AppleScript

was attempting to coerce the value of offendingObjectVariable. If an application

receives data of the wrong class and cannot coerce it to the correct class, the

value of this parameter variable is the class of the coercion that failed. (The

example at the end of this deﬁnition demonstrates how this works.)

variable is an identiﬁer for either a global variable or a local variable that can be

used in the handler. The scope of a local variable is the handler. You cannot

refer to a local variable outside the handler. The scope of a global variable can

extend to any other part of the script, including other handlers and script

objects. For detailed information about the scope of local and global variables,

see “Scope of Script Variables and Properties,” which begins on page 252.

EXAMPLES

The following Try statement provides an error handler for the Choose File

command. (For a complete description of the Choose File command, see the

AppleScript Scripting Additions Guide.) The Choose File command returns an

error if the user clicks the Cancel button in the Choose File dialog box. The

error handler gives the user a chance to continue if an error occurs.

try

choose file

set fileName to result