I would expect it to work. After all, it could be incredibly useful to bump
that up to a :header-args:plantuml: property on the heading

On Thu, Apr 15, 2021 at 12:48 PM CS Suehs <skelter.net@gmail.com> wrote:

> Nick,
> I had the :cache yes on the same line with #+BEGIN like
> #+BEGIN_SRC plantuml :file helloworld.png :cache yes
>
> When I change to your method, caching seems to work.
> It looks like setting it as a section property also works.
>
> Thank you.
> Should I expect the setting on the BEGIN_SRC line to work?
>
> On Tue, Apr 13, 2021 at 7:16 PM Nick Daly
> <nick+orgmode@despisinggravity.com> wrote:
> >
> > CS Suehs <skelter.net@gmail.com> writes:
> >
> > > Should I expect PlantUML source blocks and their resulting images to
> > > be cached and respect `:cache true` ?
> >
> > Yes.
> >
> > > In my experience they regenerate every export, even with :cache true.
> >
> > Can you provide an example?
> >
> > This example caches correctly for me on v9.1.14.
> >
> >     #+name: helloworld
> >     #+header: :cache yes
> >     #+BEGIN_SRC plantuml :file helloworld.png
> >       @startuml
> >       Hello --> World
> >       @enduml
> >     #+END_SRC
> >
> >     #+RESULTS[f29ead8751dde1b4c4ee1b8fcb97e133c75eed0d]: helloworld
> >     [[file:helloworld.png]]
> >
> > The only time I've seen caching break is if the diagram imports an
> > external file.  In that case, the diagram doesn't regenerate often
> > enough, because org doesn't notice that the external file changed.  The
> > fix to that is to include the hash of the external file as a dependent
> > var.
> >
> >     #+name: md5
> >     #+BEGIN_SRC shell :cache no :var afile="PLACEHOLDER"
> >       md5sum $afile
> >     #+END_SRC
> >
> >     #+name: cache-correctly
> >     #+header: :var md5input=md5("data.txt")
> >     #+BEGIN_SRC R :exports results :results output graphics :file
> data.svg
> >       aData <- read.csv("data.txt")
> >       ggplot(data = aData,
> >              mapping = aes(x = aData$id, y = aData$value))
> >     #+END_SRC
> >
> > Thanks,
> > Nick
>
>