[AUCTeX-devel] Difficulties understanding the behavior of TeX-parse-argument

[Mosè Giordano]

Hi guys,

I'm having a hard time understanding why this code

    (let ((foo '(("foo") ("bar"))))
      (TeX-parse-argument t '(TeX-read-key-val foo)))

works but this

    (TeX-parse-argument t '(TeX-read-key-val '(("foo") ("bar"))))

doesn't, resulting in a wrong-type-argument error.  In the outer
`cond` of `TeX-parse-argument', both codes enter the `(listp arg)'
branch and in the next `cond' they enter then the `(symbolp head)'
branch, but the two codes run differently if the CDR of `arg' is a
symbol or a lisp expression.  Why?

I spotted this problem trying to fix a bug in `style/biblatex.el'.  I
defined completion for some macros with `TeX-arg-key-val <list>',
being `<list>' a lisp expression instead of a new variable.  After
some tests I noticed that replacing quotation with apostrophe with a
`quote' function fixed the problem and I pushed the commit 830437f to
the repository.  I can swear that that change yesterday fixed the
problem, before pushing the commit I byte-compiled the style file and
restarted Emacs to verify it worked, but today I found that it was
completely useless.  This looks like a Heisenbug to me!

I know that the problem in `style/biblatex.el' can be fixed defining
new variables to be given as argument to the `TeX-arg-key-val's, but
I'd like to understand if I can avoid those variables.

Thanks,
Mosè