Re: [PATCH] ob-tangle.el: restore :tangle closure nil behavior

[Ihor Radchenko]

Tom Gillespie <tgbugs@gmail.com> writes:

>> My confusion about you patch comes from the fact that
>>
>> #+begin_src emacs-lisp :tangle (if (= 1 1) "yes")
>> 2
>> #+end_src
>>
>> works just fine on main.
>
> It appears to work fine on main, but that is because
> what is actually happening behind the scenes is that in the test
> (unless (or (string= src-tfile "no") ...) ...) the actual comparison is
> (string= "(if (= 1 1) \"yes\")" "no") which appears to work, but is
> not comparing the result of the closure, only its string value.

What I see when tangling a file with the above code block is

Debugger entered--returning value: ("emacs-lisp" "2" ((:colname-names)
         (:rowname-names) (:result-params "replace")
         (:result-type . value) (:results . "replace")
         (:exports . "code")
         (:tangle . "yes") <---------- evaluated
         (:lexical . "no")
         (:eval . "never-export") (:comments . "link")
         (:hlines . "no") (:noweb . "yes") (:cache . "no")
         (:session . "none")) "" nil 2 "(ref:%s)")
  (org-babel-get-src-block-info)
* (#<subr org-babel-tangle-single-block> 1)
* (apply #<subr org-babel-tangle-single-block> 1)
* (org-babel-tangle-single-block 1)
  (org-babel-tangle-collect-blocks nil nil)
  (org-babel-tangle nil)
  (funcall-interactively org-babel-tangle nil)

>> I admit that I don't fully understand your use case.
>
> I want to use a closure to conditionally control whether a block will tangle.
> If I hardcode :tangle no, then :var x=(error "oops") will not evaluate. The
> (error "oops") is a placeholder for a number of things that will result in
> an error if the condition for :tangle (when condition "file-name") is not
> satisfied.

Do you mean something like

#+PROPERTY: headline-args :var x=1

#+begin_src elisp :tangle (if (= x 1) "yes" "no")
...
#+end_src
?

>> Something like (org-babel-get-heading-arg :tangle info/params)
>
> I need to go to bed, because I definitely started on an implementation
> of that I forgot about it as a potential solution. Yes, this seems like
> a better and clearer way to go about it.

Let me know if you need any help.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>