Re: [BUG?][PATCH] Should the `lexical-binding' variable be bound during src block with :lexical t? [9.4.6 (9.4.6-ga451f9 @ /home/n/.emacs.d/straight/build/org/)]

[No Wayman]

> My thoughts on this would be that if lexical-bindings is 
> supposed to be
> bound to t, it should be done by eval when it gets a non-nil 
> value for
> it's optional argument. If I execute (eval FORM t) in an emacs 
> lisp
> buffer, it looks like lexical-bind is not set either, so I don't 
> think
> it should be in org either. To set it means we could get the 
> same code
> behaving differently depending on whether the source block is 
> 'tangled'
> and then evaluated or evaluated within org, which doesn't feel 
> right.
 

I agree that we should avoid inconsistency. However it is already 
present.
You can verify this with the following src block:

#+begin_src emacs-lisp :lexical t :tangle ./dynamic.el :results 
verbatim
(symbol-value lexical-binding)
#+end_src

1. `org-babel-execute-src-block' with point in the src block => 
nil (lexical binding enabled)
2. `org-edit-special' with point in the src block, 
`eval-last-sexp' within *Org Src* buffer => t (lexical binding 
enabled)
3. Tangle to the block to "dynamic.el", `eval-last-sexp' within 
"dynamic.el" => nil (dynamic binding)

> Might be worth asking on emacs-devel why (eval FORM t) does not 
> set this variable?

I understand why it doesn't. Elisp can be interpreted independent 
of a buffer, and different buffers need to distinguish which scope 
to use. 
It's more a question of what do we gain by leaving it unbound 
while evaluating a src block?
A user can rebind `lexical-binding' without hurting anything. The 
only case I can think of is if they intend to use it as a free 
variable, it won't be free. I can't imagine a use case where that 
would be true while the user is also explicitly requesting lexical 
binding, though.
IMO, it should be set during evaluation (addressed by my patch).

An alternative solution would be to allow one to set the lexical 
environment as part of the header args. e.g.

#+begin_src emacs-ilsp :lexical ((lexical-binding . t) t)
(symbol-value lexical-binding)
#+end_src

That way we offer the full flexibility of `eval' to those who 
would use it.

A separate issue, but one worth considering, is whether or not 
tangling a `:lexical t` src block should automatically add the 
file-local variable line in the tangled file.

Prior confusion (its not just me, I swear):

https://emacs.stackexchange.com/questions/61754/how-can-i-enable-lexical-binding-for-elisp-code-in-org-mode#comment100554_61758

https://lists.gnu.org/archive/html/emacs-orgmode/2019-08/msg00247.html