Re: babel default header args as functions

[Tom Gillespie]

Hi Bastien,
    Here are some examples that I have in mind. One example would be
to simplify my hacked solution to from
https://lists.gnu.org/archive/html/emacs-orgmode/2020-09/msg00175.html.
I could apply that to all the headings in a subtree by defining it
once in the property drawer. Another example would be to only tangle a
block when a certain value was true, it would require using an
unofficial header convention to store the name of the file per block,
or it could use the name of the block. I do something like that around
line 1336 of 
https://raw.githubusercontent.com/SciCrunch/sparc-curation/9c08e82ab0b8c497e01d8542ecb1195d40111767/docs/setup.org.
Another extremely common use case I have is detecting that I am
running on a particular host which requires a slightly different value
than some other host that I run regularly on, for example if I am
going to be running a large number of blocks using :dir and on host a
it needs to be /home/my-usual-user-name/working/ and on another it has
to be /home/my-other-user-name/working/ because I wasn't the first
user named tom to get an account on that system. Similar use case
would be switching the database port based on which host I was on
since I often forward a remote database port via ssh while also having
a local database on that port as well. Another case would be to be
able to blanked switch :tangle from yes to no based on whether a
sentinel file was present or any other condition you could imagine
(this is similar to the second example). Best!
Tom


On Sat, Sep 5, 2020 at 10:00 PM Bastien <bzg@gnu.org> wrote:
>
> Thanks for weighing in into this discussion.
>
> Tom Gillespie <tgbugs@gmail.com> writes:
>
> > I have a number of use
> > cases that I can imagine would benefit greatly from being able to
> > define a :header-args: :header (lambda () "yay!") property as a
> > closure
>
> Can you give some examples? I would love to get a better sense of
> the usefulness of this feature.
>
> --
>  Bastien