Re: [dev] About a beamer back-end

[Rasmus <rasmus@gmx.us>]

"Sebastien Vauban"
> IIUC, you seem to say it's difficult to use the overlay notation, but
> you can
> use it very easily that way:
> ** Overlay effects \\ Keep the suspense!
>
> *** Time bomb                                                        :B_block:
>     :PROPERTIES:
>     :BEAMER_env: block
>     :END:
>
> 1. <2-> Two more to go
> 2. <3-> One more to go
> 3. <4-> Last chance...
> 4. <5-> BOOM!
>
> The same applies for itemized lists.

If I want to do piece-wise I can even implement it with a single line in
the header.  (I usually don't want that, though).

Your way is tedious unless you are very certain about your structure.
Say I want a point in between:

> 1. <2-> Two more to go
> 2. <3-> One more to go

I would have to renumber stuff throughout the reminder of the slide.
Personally, I find that I often do, but perhaps this is a flaw in my
organization skills?


I would rather use the IMO more stable \pause command, but this is still
not elegant.  What I ask for is a more general approach, which is
perhaps not specific to beamer/does not rely on LaTeX commands.

Consider an example with a block

#+begin_src org
** Beamer title     :B_frame:
   :PROPERTIES:
   :BEAMER_env: frame
   :END:

 - points leading up to example
 - I want a pause before presenting the example

## I could put in a pause here, 
## but it belongs to the example.
## Logically, it thus does not belong here

*** pause	:B_ignoreheading:
    :PROPERTIES:
    :BEAMER_env: ignoreheading
    :END:
    \pause
## I have to impose a pause in a separate block.
## But this is an annoying hack.

*** Letting variables take on value.    :B_example:   
    :PROPERTIES:
    :BEAMER_env: example
    :END:
## a \pause is no good here, as the title is not hidden

    Let $x = y$ and $y=1$.  Then $x=1$.

#+end_src

It would be nicer to have a pause tag/property, say.  It would also be
more org-ish, and could work across exporters.  Pause of the <n> syntax
is not that pretty, and is beamer-specific.

Perhaps in general it would be more beneficial to think of a
org-e-slides, and a specialized org-e-slides-beamer?  (The main reason
for using Beamer to me is math and note support).

–Rasmus

-- 
When in doubt, do it!