How can you pass an empty variable to optional parameters?

[Kha]

Hey guys,

I am dipping my toes on creating Applescript libraries but I am stuck on a situation. So far, I am trying to create a mock example of an entry using all the parameters available for the "display dialog" command and then selectively pass the information I want to it to give me the desired outcome. This is where I am right now...

on display_dialog_box(dialog_text, default_answer, hidden_answer, button_1, button_2, button_3, default_button, cancel_button, with_title, with_icon, giving_up_after)

set theResult to display dialog dialog_text ¬
		default answer default_answer ¬
		hidden answer hidden_answer ¬
		buttons {button_1, button_2, button_3} ¬
		default button default_button ¬
		cancel button cancel_button ¬
		with title with_title ¬
		with icon with_icon ¬
		giving up after giving_up_after

end display_dialog_box

This works if I am planning to use all the optional parameters available, but what I am having trouble with is passing an empty value to the parameters I don't want without Applescript throwing me an error. For example, if I don't want a default answer or a hidden answer to be displayed, is there a way I can pass an empty parameter to these that would make Applescript skip the optional parameter and continue on?

I tried using "", null, missing value... but I can't figure it out.

The reason I am trying to do this is to avoid making all sorts of combinations for what is basically the same subroutine.

The knowledge I am getting from this will make me understand how to optimize my code on much more complex subroutines.

Thanks for reading this far!

[hayne]

AppleScript is not designed to be terse.
If you are trying to make your AppleScript as terse as possible, you are probably doing it wrong.

[acme.mail.order]

you'll probably have to wrap each parameter in an "if the parameter is not empty..." bit.

But I can't determine what this routine is doing for you - all the action does is repackage the parameters nearly word-for-word. In this case i would just put the display dialog inline and customize as necessary.

[Kha]

acme.mail.order, I am just trying to use this as an example for learning. I have other programs that passing empty parameters for them in the method i am trying to figure out would make programming them much easier. Adding those "if..." statements would only make programming longer and complex, but I guess going through the long route is the only way to do it.

hayne, I guess you are right about that. I never encountered any script/tutorial that resembles what I am trying to do before, and now I know why. Applescript design limitation...

[renaultssoftware]

It's not really an AS limitation. Basic functionality is implemented and it's up to you to use the classes you want for your purposes.

You could try:

on doStuff(x,y,z)
if x is missing value then
-- x is nil and specific parts should be used
end if
if y is missing value then
-- y is nil... etc
end if
actuallyDoSomething()
end doStuff

-- and now you can call it like this:
doStuff(missing value, missing value, 3)