Re: Self-sufficient Org file with customised export? :eval-when?

["Berry, Charles" via "General discussions about Org-mode." <emacs-orgmode@gnu.org>]

> On Apr 30, 2020, at 11:55 AM, akater <nuclearspace@gmail.com> wrote:
> 

[deleted - discussion of html export]

> -----
> 
> 
> If I may prematurely offer my vision: Common Lisp has special operator
> eval-when which specifies when the enclosed code is to be evaluated (or
> compiled).  Example:
> 
> (eval-when (:compile-toplevel) (defun f () ..))
> 
> specifies that function f should be defined during compilation only.
> 
> I believe it would be neat if Org-mode widely supported :eval-when
> header argument inspired by Common Lisp's eval-when.  Usage examples
> would be:
> 
> #+begin_src emacs-lisp :eval-when compile load
> ..
> #+end_src
> 

You can effectively do this by using an elisp expression for the value of an :eval arg like this:


#+begin_src emacs-lisp :eval (or (bound-and-true-p my-eval-flag) "no")
"done"
#+end_src

which honors the value of `my-eval-flag' if there is one.

You can also use a call to a src block. e.g. `:eval my-src-block(a=1,b=2)'

HTH,

Chuck