Re: Question about handler
Re: Question about handler
- Subject: Re: Question about handler
- From: Graff <email@hidden>
- Date: Fri, 02 Apr 2004 13:39:14 -0500
On Apr 2, 2004, at 10:51 AM, Robert Poland wrote:
You can set pictureCount as a global variable. Do this at the top of
the script:
global pictureCount
The values of global variables are saved between runs so it is a good
idea to initialize them to clear any retained values that might mess
up your calculations. You are doing this in the open handler already
so this shouldn't be a problem.
- Ken
Is there a way to clear a variable like in C?
i.e. global pictureCount ()
You can't really clear a variable in C, all you can do is to set it to
a different value. Maybe one that is as neutral as possible, such as
zero for an int or NULL if it is a pointer. This is pretty much true
also with AppleScript. I do believe there is a hidden null value in
AppleScript that you can invoke but usually it's not needed and it's
not always a good idea to do.
However, remember that variables in AppleScript aren't stuck to one
type like those in C. So you can set the variable to something else
that is blank, for example:
set pictureCount to ""
or
set pictureCount to {}
There is also a predefined constant which is designed for you to set a
variable to so that you can tell it hasn't been accessed yet. That
constant is "anything":
set pictureCount to anything
-- do some stuff
if pictureCount is anything then set pictureCount to 0
There is also the "missing value" constant which is returned when a
variable doesn't have a value. I believe it can be used in the same
way as the "anything" constant:
set pictureCount to missing value
-- do some stuff
if pictureCount is missing value then set pictureCount to 0
You can read more about these constants here:
<
http://developer.apple.com/documentation/AppleScript/Conceptual/
AppleScriptLangGuide/AppleScript.45.html>
In a script such as the one in the e-mail that I replied to it's enough
just to explicitly set the variable to zero at the start of the script.
- Ken
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