Saving and Loading Libraries of Handlers

In addition to defining and calling handlers within a script, you can access handlers from other scripts. To make a handler available to another script, save it as a compiled script, then use the load script command to load it in any script that needs to call the handler. You can use this technique to create libraries containing many handlers.

For example, the following script contains two handlers: areaOfCircle and factorial:

-- This handler computes the area of a circle from its radius.

-- (The area of a circle is equal to pi times its radius squared.)

on areaOfCircle from radius

    -- Make sure the parameter is a real number or an integer.

    if class of radius is contained by {integer, real}

        return radius * radius * pi -- pi is predefined by AppleScript.

    else

        error "The parameter must be a real number or an integer"

    end if

end areaOfCircle

-- This handler returns the factorial of a number.

on factorial(x)

    set returnVal to 1

    if x > 1 then

        repeat with n from 2 to x

            set returnVal to returnVal * n

        end repeat

    end if

    return returnVal

end factorial

In Script Editor, save the script as a compiled Script (which has extension scpt) or Script Bundle (extension scptd) and name it “NumberLib”.

After saving the script as a compiled script, other scripts can use the load script command to load it. For example, the following script loads the compiled script NumberLib.scpt, storing the resulting script object in the variable numberLib. It then makes handler calls within a tell statement that targets the script object. The compiled script must exist in the specified location for this script to work.

set numberLibrary to (load script file "NumberLib.scpt")

tell numberLibrary

    factorial(10)             --result: 3628800

    areaOfCircle from 12      --result: 452.38934211693

end tell