beginning AppleScript question

Is LibreOffice AppleScriptable? It must have an AppleScript Dictionary in order to be scriptable.

This web page seems to indicate it isn't: Scripting LibreOffice - LibreOffice Help

That would depend on the particular app.

Every App has its own Dictionary of commands. You have to look at the Dictionary for the App to see what commands it takes

System Events responds to the keystroke command, but it is kind of a universal program, so you have to make sure the thing you want the keystroke to appear in is frontmost.

For example, this will put text into a new TextEdit document.

tell application "TextEdit"

activate

make new document

tell application "System Events"

keystroke "Hello, World!"

end tell

end tell

The outer Tell block sets up a new document in TextEdit which was told to come to the front with "activate."

The inner Tell block instructs "System Events" to type the keys passed as a string.

You can run commands with System Events, also.

tell application "TextEdit"

activate

make new document

tell application "System Events"

keystroke "Hello, World!"

keystroke "s" using command down

end tell

end tell

That will add the text to a new document and send the Save command (cmd-s).

To view an App's Dictionary, use the Open Dictionary command from the File menu and find the App. If it is grayed out, it doesn't have a Dictionary and can't be scripted except as shown above with System Events.

Well, most text-based apps will have a dictionary that allows you to enter text in the document with their own commands. The System Events allows access to apps that provide only minimal AppleScript support or none at all.

It also allows you to access menus and click buttons via UI Scripting, which is even more difficult to comprehend.

A window is like a class. You can send messages to a class with a Tell block.

tell window 1 of application TextEdit to close.

A property in AppleScript is like an instance variable or method of a class. Some properties can be set, but others are read only.

Elements are like properties that are classes in and of themselves.

UI scripting is clicking menus and buttons with a script.

Click menu 3 of menu 2 of menubar 3 of application "Foo"

Click button 3 of tab group 4 of window 3 of ...

Instead of

let myWindow = TextEdit.Windows(1)
myWindow.titled = true
myWindow.name = "Foo"

You would

tell application "TextEdit"
     set myWindow to window 1 of windows
     set titled of myWindow to true
     set title of myWindow to "Foo"
end tell

The latter makes more sense to someone who doesn't understand dot-syntax or whatever property-escaping syntax is used.

The Swift-like syntax is likely more readable than Objective-C, but still is not as obvious to someone who has no object-oriented programming experience.

I don't know what the AppleScript Dictionary for Emacs is. I don't know if it understands what a window is.

If I substitute "TextEdit" for "Emacs" it runs just fine.

Every App has its own AppleScript "API." You have to learn each. Many stick with similar conventions, but you can't just assume any given app understands what a "window" is or that the App is actually AppleScriptable.

As you can see in this snippet, the color coding indicates what is understood by the app (not Script Editor or AppleScript itself)

tell application "TextEdit"

repeat with windowId from 1 to 2

if name of window windowId is "left" then

activatewindowwindowId

end if

end repeat

end tell

AppleScript knows that application is a class

It shows that TextEdit knows that name is a property of a window and that windowId is a variable.

It knows that TextEdit can activate a window class object.

This was the first book I read on AppleScript and I think it did a pretty good job, but I wasn't familiar with anything beyond Basic and Fortran when I read it.

Danny Goodman's Applescript Handbook: Danny Goodman ...

This is a good site for learning and seeing examples: http://www.macscripter.net

This MacTech publication is for converting from VBA to AppleScript in Office, it may help in understanding some idiosyncrasies: Converting VBA Macros to AppleScript in Microsoft Office - MacTech

Then there's this: http://macosxautomation.com/applescript/

How about

get windows of process "Emacs"

Again, System Events is global, and it has no windows of its own.

You essentially activated Emacs, then asked System Events for its own windows.

You seem to be thinking about it linearly and not objectively.

Both application "Emacs" and application "System Events" are objects that respond to messages

get windows only applies to the object "System Events" whose class is "application"

Since you provided no other context, it can only assume you want to know about its windows.

Your AppleScript was essentially,

Emacs.activate()

return "System Events".Windows()

If that is not clear, why would the class "System Events" know anything about the windows of class "Emacs"?

EDIT: Maybe this is better phrasing:

Why would calling the Windows method of "System Events" know to give you information about the windows of another class which you did not specify?