ConcurrentModificationException gets thrown if a Presentation.extension() contains verticalSlides inside of which you call Presentation.anotherExtension() about kslides HOT 6 CLOSED

Trying to import both Presentation and VerticalSlidesContext into one scope by using:

fun Presentation.content() {
    verticalSlides {
        dslSlide {
            content { }
        }
//        Moved to extension function
//        dslSlide {
//            content { }
//        }
        nestedContent(this@content)
    }
}

fun VerticalSlidesContext.nestedContent(presentation: Presentation) = with(presentation) {
    dslSlide {
        content { }
    }
}

yields the same error.

from kslides.

Hi Filip,

The issue is there are two dslSlide() calls: VerticalSlidesContext.dslSlide() and Presentation.dslSlide()
Prior to moving the dslSlide() call to an extension function, you are calling it in the context of VerticalSlidesContext.
With the extension function, you are calling it in the context of Presentation. Calling the Presentation version of dslSlide()
in the context of a VerticalSlide causes bookkeeping problems (as you saw).

The solution is easy. The extension function should be defined as:

fun Presentation.nestedContent(verticalSlidesContext: VerticalSlidesContext) {
  verticalSlidesContext.dslSlide {
    content {
      h1 { +"I am here" }
    }
  }
}

and invoked with:

    nestedContent(this)  // where this is the VerticalSlidesContext of verticalSlides{}

Please let me know if this addresses your problem. If you still have unnecessary clutter, please let me know and we can get it right.

Cheers,
Paul

from kslides.

Very interesting. It's still a little shady for me how exactly both of those contexts interact with one another, especially with extension functions involved. Must be my inexperience with the internal implementations of DSLs in Kotlin.

Nonetheless it completely solved my problem and my presentation is now neatly divided into functions, thank you!

One last thing - I am not knowledgeable enough in Kotlin to determine such thing, but maybe it would be a good idea to include this example in the README? It certainly was not obvious for me why extentind Presentation and passing VerticalSlidesContext solved the issue, but extending VerticalSlidesContext and passing Presentation did not.

Either way, thank you very much!

from kslides.

Yes, it is an interesting situation when you have multiple applicable this values. The Kotlin 1.6.20 release previewed context receivers, which help with the case of multiple thisvalues. I have not added context receivers to kslides because they are not supported in libraries (that may have since changed).

Also, the confusion you went through would have been avoided had I used a different name for dslSlide{} in the VerticalSlide context, but that muddies things up when you move slides around.

I will add a note about this to the README.

If your slides are public, please send me a link so I can show them as an example of what is possible.

Thanks,
Paul

from kslides.

The presentation slides will be published in September. If, by that time, you will still be interested, I will happily share the link :>

I believe that using the same name (dslSlide) in both contexts was a good choice. Unfortunate that such pitfalls exist, but I think it's worth the consistency.

from kslides.

I added a note to README.md, and yes, I would appreciate you sending a link to [email protected] when you finish them.

Thanks.

from kslides.