Add specified tag to comments

Question

I’ve been trying to learn AppleScript, but I simply don't get how you develop a script from scratch. Do you start with the Applescript library? Do you start with lines of script that you already know? The books I‘ve read don't seem to really explain the workflow process for actually creating scripts. They simply describe scripts; yet, they say it it’s easy to develop scripts because it’s almost like the English language.
Anyway, I want to develop a script that will add specified tag(s) to selected tracks.
I got this bit of code from another script, and tried to add what I thought might work, but needless to say, it doesn’t.
tell application "iTunes"
set theTrack to (item 1 of (get selection))
set commentText to comment of theTrack
set commentList to paragraphs of commentText
set newComment to {“youtube download”}
Can anyone assist me?

Answer 1

I don't know whether it's the nature of the language, the skill of the author, or just me, but I've never found a book that I think really teaches AppleScript.
AppleScript is both simple and complex at the same time. Its simplicity comes from the natural-language format of the application, its complexity comes from the diverse (and inconsistent) AppleScript implementation within other AppleScripts.
You see, unlike most other languages the basic abilities of AppleScript are fairly limited. Where it gets its power is in its ability to drive other applications to do the heavy lifting. For example, I wouldn't even consider writing an AppleScript to rotate an image or, in your case, edit an audio file, but it's almost laughably easy to write an AppleScript to tell some other application (e.g. Photoshop for the image, iTunes for the audio file, etc.) to do it.
And that is really where the learning curve of AppleScript comes in - knowing which applications to target, and the specific implementation of AppleScript within that app.
The AppleScript Editor helps some here - it allows you to read the AppleScript dictionary of any application which exposes the commands the application can execute, as well as the classes of objects the application understands.
In your case, if you open the iTunes dictionary in AppleScript Editor you'll see, amongst other things, a track object, along with the properties of a track (i.e. the data that iTunes knows about that track and can manipulate). Familiarity with various application dictionaries is key to getting the most out of AppleScript (you don't need to memorize the entire dictionary, just have an idea of what the app can do, then use AppleScript Editor to view the dictionary and explore).
So for example, how did you know to add: “set newComment to commentText & return & "youtube download"“? Did you look that up in the dictionary, reference book, or did you just know that script you needed?
In this particular case, that's just pure vanilla AppleScript.
As I mentioned above, the base AppleScript language has limited scope that mostly hinges around basic object classes (e.g. 'integer', 'text', 'boolean', etc.) as well as operators (+, -, *, /, etc.), logic ('if/then/else') and loops (e.g. 'repeat').
Your goal required building a new comment for the track where the new comment consists of the existing comment text plus some additional text, so that's what that statement does:
set newComment to commentText & return & "youtube download"
The & character is used to concatenate string (text) objects together. In this case the command combines commentText (previously declared as the existing comment for this track), a return character, and the string of characters "youtube download".
Once those strings have been concatenated they're assigned to the variable newComment which can be used to reference that data later in the script (in this case, on the very next line, but it could be much further away).
That's pure AppleScript. That line of code doesn't depend on any other application (as long as commentText is properly defined, of course).
The trick, and the part you were missing, was knowing to pass that data back to iTunes to apply it to the track.
So how do you learn this stuff?
Well, the AppleScript Language Guide covers pretty much all the basic/pure AppleScript stuff (base classes, operators, loops, handlers, etc.), but it is really a reference guide - something to refer to as needed, not to read end-to-end, so keep it handy but don't sweat it.
The second resource is the AppleScript Editor, especially the dictionary viewer to see what each application can do.
Then there's trial and error - poke around and see what happens.
Then there are forums like this one, and MacScripter where you can ask questions to the community - by and large the people who love AppleScript really LOVE AppleScript and are happy to help solve any problem or question.