bug#34975: 26.1.92; In backquote, the comma marker does not work with variable name started with dot

[Michael Heerdegen <michael_heerdegen@web.de>]

Xu Chunyang <mail@xuchunyang.me> writes:

> For example,
>
> (let ((.foo 42))
>   (list .foo))
> ;; => (42)
>
> (let ((.foo 42))
>   `(,.foo))
> ;; => ((\,\. foo))
>
> I expect both of them returns (42). is it a bug?

AFAIU ,. is a reader macro:

(car (read ",.foo"))

  ==> \,\.

I dunno or have forgotten for what it had been intended, there are no
real uses in the Emacs Elisp sources.

> (let ((.foo 42))
>   `(,.foo))

You would have to write it differently, e.g.

(let ((.foo 42))
  `((\, .foo)))

  ==> (42)


Michael.