Creating a new paragraph style with try/catch (jsx)

[58234121]

Good Morning, 

I'm hoping someone can help me understand this snippit, I got from the adobe scripting guide. (createStyles.jsx) Specifically line 4 below. 

    myName = myParagraphStyle.name;

My understanding is that I am assigning "myParagraphStyle" to a variable. But because It may or may not exist, (and throws an error when it doesn't) I have to put it in the try{} statement. The catch statement is what gets executed when an error would otherwise be thrown. In this case it creates myParagraph style. 

So what does  myName = myParagraphStyle.name; do? And why bother assigning it to a variable? The variable never gets used, but it does get reassigned for myColor.name, and myCharaterStyle.name.

//Create paragraph style 
try{
    myParagraphStyle = myDocument.paragraphStyles.item("myParagraphStyle");
    myName = myParagraphStyle.name;
}
catch (myError){
    myParagraphStyle = myDocument.paragraphStyles.add({name:"myParagraphStyle"});
}

[Jongware]

Remove the try..catch error handler and run your script to see what that line is for.

Make sure this style does not exist!

Pay close attention to what the error line number is, and what the error message says. Then you should be able to reason why it is like that.

[58234121]

Take the whole try/catch off? It points to line 4 and says that the object is invalid. Thats because it can't access myParagraphStyle.name because it still doesn't exist. right? Does that also mean that myDocument.paragraphStyles.item("myParagraphStyle") was "successfully" assigned to myParagraphStyle. Because otherwise the error would have been thrown from line 3.

[Jongware]

🙂You're almost there! Yes: the error says that "myParagraphStyle.name" does not exist, but this indeed does NOT automatically mean that "myParagrahStyle" does not exist! It does -- and it has the value "undefined". That IS a valid value (hence, you don't get an error on that line) but the next line tries to access this as if it's an object, "undefined.name", and THAT shows the error. So assigning a non-existent object is okay ... as long as you don't try to use its (non-existent) properties.

For even more fun with this, after the assignment, add this line:

alert (myParagraphStyle.constructor.name);

It will show you "ParagraphStyle" -- even though it does not exist! Think of this like a variable of some type that is declared but not yet has been given a value: 'var x' is pretty much the same, as here the value of 'x' is undefined and you cannot do "alert (x.length)" nor "alert (x+1)", and expect a meaningful result.

[58234121]

This is fantastic! Thank you so much! One more related question. I'm using a similar try/catch setup to create a swatch. It works as expected for the most part, but when I tried to "try" for the default [Black] swatch it wigs out. Are there special rules for the bracketed swatches? because "Black" works, but "[Black]" doesn't. I hope that makes sense.

[Jongware]

Well I'd need to see what you are attempting there before I could say. I think the main difference is that you cannot do anything to standard swatches -- renaming, changing their color model, etc. But inquiring their name, as with your paragraph style example, should be okay.

[58234121]

I just realized that [black] can't be deleted, so there is really no reason to use the try/catch, because it will always be there. So I'm just creating extra work. 

But I guess for novelty's sake, here is the code that fails. If I take the brakets off the word Black, it works.  

try{
    myColor = myDocument.colors.item("[Black]");
    myName = myColor.name;
}
catch (myError){
    myColor = myDocument.colors.add({name:"[Black]", model:ColorModel.process, colorValue:[0, 0, 0, 100]});
}

[karthikS]

HI,

Try below code and compare with your code:

try{
myParagraphStyle = app.activeDocument.paragraphStyles.itemByName("myParagraphStyle");
myName = myParagraphStyle.name;
}
catch (myError){
myParagraphStyle = app.activeDocument.paragraphStyles.add({name:"myParagraphStyle", appliedFont:"Avenir Next", fontStyle:"Regular", pointSize:6, leading:8, justification:Justification.RIGHT_ALIGN}); // extra property
}

Thanks,

Karthik