Re: Pandoc #4317 side effect

[John MacFarlane <jgm-TVLZxgkOlNX2fBVCVOL8/A@public.gmane.org>]

If you use the raw attribute to mark up content as "raw beamer,"
as suggested earlier in this thread, it will not appear in
reveal.js output. Demo here:

https://pandoc.org/try/?text=%23+Introduction%0A%0A%60%60%60%7B%3Dbeamer%7D%0AHey+this+is+raw+beamer!%0A%60%60%60%0A%0A%23%23+Slide+one%0A%0Acontent%0A%0A%23%23%23+Vertical+slide%0A%0Acontent+vertical%0A&from=markdown&to=revealjs&standalone=0


Thomas Chevrier <tchevri-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:

> Hi folks,
>
> it's been exactly a year now and I am still not able to upgrade my version 
> of Pandoc - stuck pre 2.7, because of the adverse change.
> Indeed, the "upgrade" for reveal.js users caused my latex beamer code to 
> break down.
> I have tried multiple things without luck - I also tried a lua filter, but 
> that did not work - no matter what, the content gets "slapped" onto a slide.
> As JGM suggests (was great watching him talk about Pandoc at TUG 2020 
> keynote address), I'd love to be able to simply be able to have content 
> escape being slapped onto a slide - I believe that's precisely the spirit 
> of Beamer, which uses <mode> heavily for that purpose.
> I also thought that was the spirit of pandoc - as you were setting in the 
> yaml header your level for displaying on slides, but i have been clearly 
> proven wrong. :-(
> One option would be to recompile pandoc without that change, but because of 
> the bloomberg API, I am forced to be on windows, which would make this 
> solution cumbersome at best (would be straightforward on linux though).
>
> FYI, I posted back then on SO, got only 2 upvotes and 2 bookmarks, but no 
> answer, not even a comment :-(
> https://stackoverflow.com/questions/57614387/pandoc-4317-forces-content-under-title-slides-to-be-included-in-a-frame-in-pand
>   
>
> Could anyone *please* help me?
> many thanks in advance
> thomas
>
>
> On Wednesday, August 28, 2019 at 12:23:15 AM UTC+8 John MacFarlane wrote:
>
>>
>> To summarize the issue here, which concerns a change to slide 
>> show formats: 
>>
>> Prior to 2.7, versions of pandoc only put material under the "slide 
>> level" headings on slides. If you set slide level to 2, then 
>> only material under level-2 headings would appear on slides, 
>> and text under level-1 headings would not appear at all 
>> (though level-1 headings would create "title slides" with 
>> just the section title). 
>>
>> Reveal.js users consistently complained (#4317, #5237) that 
>> this made it hard to structure reveal.js 2D slide shows, in 
>> which it is common to have the "top" slide on each column 
>> contain both a title and some text. 
>>
>> In response, I changed pandoc in 2.7 -- as the changelog says, 
>>
>> > Slide show formats behavior change: content under headers less 
>> > than slide level is no longer ignored, but included in the title 
>> > slide (for HTML slide shows) or in a slide after the title slide 
>> > (for beamer). This change makes possible 2D reveal.js slideshows 
>> > with content in the top slide on each stack (#4317, #5237). 
>>
>> The change to reveal.js has been welcomed by reveal.js users, 
>> but the change to beamer is apparently not welcome by everyone. 
>> The reason I made the change to both formats is because I want 
>> slide shows to work the same no matter what output format you 
>> use. (So you can switch from beamer to reveal.js, for example, 
>> and the slides will look more or less the same.) 
>>
>> I had thought the beamer change was innocuous, since it could 
>> be worked around by people who wanted to include content under 
>> top-level section headings but not in the slides, e.g. by using 
>> a filter to strip out this content. 
>>
>> Unfortunately, Thomas Chevrier's use case can't be handled that 
>> way. He wants to insert raw tex commands that (a) can't be 
>> stripped out but (b) only work if they're outside the 
>> 'frame' environment created for a slide. I can't think of any 
>> workaround for this. 
>>
>> One possible course of action would be to revert the beamer 
>> change while keeping the reveal.js change. This would potentially 
>> have two bad consequences: 
>>
>> 1) slide shows would render differently (in content, not just 
>> form) in reveal.js and beamer. 
>>
>> 2) this may break slide shows that were constructed using the 
>> new behavior since 2.7 was released. 
>>
>> A less radical change might be to introduce special Div whose 
>> contents get moved outside the slide itself. Anyway, comments 
>> welcome. 
>>
>>
>>
>
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