Apple Event Parameters

Sometimes a lone Apple event like quit or activate will do the trick in a script. At other times, Apple events have to specify Apple event parameters. These are the data the receiver of the Apple event needs to carry out the Apple event’s instructions. For instance, if the Example 1-3 script did not include the parameter:

file "mydocument"

then the OS 9 Finder would return an error, because its open Apple event requires a reference to the object(s) to open.

Example 1-3. A Finder open Command

tell application "Finder"
   (*open is the command; file "mydocument" is the parameter *)
   open file "mydocument" 
end tell

Tip

Examples in this book will usually include comments explaining code elements. Comment characters in AppleScript are two hyphens (—) for single-line comments and parentheses containing asterisk characters (* *) for multi-line or single-line comments.

Figure 1-5 illustrates the Finder’s open Apple event with the reference to the mydocument file.

Figure 1-5. The Finder’s open Apple event

Apple event parameters can include standard data types (e.g., integer or string) or references to Apple event objects, such as a document file. Apple event objects are the items or “nouns” (e.g., a file, a folder, a database record) that some scripts interact with. See Section 1.2.6 for further explanation on handling objects in your scripts.

An Apple event can have more than one required or optional parameter. In another example, if you want your script to tell FileMaker Pro to create a new row in a database, then create is the Apple event (followed by the required keyword new). The create Apple event requires a parameter such as a record object (as in a database record or row). Otherwise, how would the database program know what you wanted to create?

The code in Example 1-4 opens a database file and then creates a new record with empty fields.

Example 1-4. Getting FileMaker to Create a New Database Row

tell application "FileMaker Pro"
   activate --brings the target application to the front
   open file "startupdisk:fm databases:myDB.fm4"
   create new record - "record" is the parameter
end tell

Example 1-4 could use the create command’s optional with data parameter to fill the new row with data, thus creating a complete database record.