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bug#49809: [PATCH] Add macro 'pcase-setq'
From: |
Stefan Monnier |
Subject: |
bug#49809: [PATCH] Add macro 'pcase-setq' |
Date: |
Wed, 04 Aug 2021 19:06:11 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
> This patch adds a `setq`-like equivalent to `pcase-let`.
> This is convenient when one wants the bindings to exist outside of
> a `let` form.
Thanks.
> This macro expands into multiple `setq` calls that are combined where
> possible.
I don't think we should try and combine them: it's not worth the
code complexity. Personally I'd even restrict the calling convention to
(pcase-setq PAT VAL), but if you want to accept the more general case
with multiple PAT+VAL, I'd prefer expanding it to a (progn (pcase-setq
PAT1 VAL1) ...). I think the resulting code would be simpler/cleaner.
> Please let me know what should be changed.
See a few more comments below.
> Subject: [PATCH] Add macro 'pcase-setq'
>
> * doc/lispref/control.texi: Document this macro.
> * lisp/emacs-lisp/pcase.el: Add this macro.
Please include the "section/function" info,
e.g. I'd write the message as:
* lisp/emacs-lisp/pcase.el (pcase-setq): New macro.
This macro is the 'setq' equivalent of 'pcase-let'.
* doc/lispref/control.texi (Destructuring with pcase Patterns): Document it.
> +@defmac pcase-setq pattern value@dots{}
> +Bind variables to values in a @code{setq} form, destructuring each
> +@var{value} according to its respective @var{pattern}.
> +@end defmac
I prefer keeping "bind" for the case where we create new variables
(i.e. let-bindings) rather than for assignments.
> +;;;###autoload
> +(defmacro pcase-setq (&rest args)
> + "Bind values by destructuring with `pcase'.
Same here.
> +\(fn PATTERN VALUE PATTERN VALUE ...)"
> + (declare (debug (&rest [pcase-PAT form])))
> + (let ((results)
> + (pattern)
> + (value))
> + (while args
> + (setq pattern (pop args)
> + value (pop args))
> + (push (if (pcase--trivial-upat-p pattern)
> + (list 'setq pattern value)
> + (pcase-compile-patterns
> + value
> + (list (cons pattern
> + (lambda (varvals &rest _)
> + (cons 'setq
> + (mapcan (lambda (varval)
> + (let ((var (car varval))
> + (val (cadr varval)))
> + (list var val)))
> + varvals)))))))
> + results))
Looks good. But could you add a few corresponding tests to
`test/lisp/emacs-lisp/pcase-tests.el`, including tests for things like
(pcase-setq `(,a ,b) nil)
-- Stefan
- bug#49809: [PATCH] Add macro 'pcase-setq', Okam, 2021/08/01
- bug#49809: [PATCH] Add macro 'pcase-setq', Lars Ingebrigtsen, 2021/08/04
- bug#49809: [PATCH] Add macro 'pcase-setq',
Stefan Monnier <=
- bug#49809: [PATCH] Add macro 'pcase-setq', Michael Heerdegen, 2021/08/04
- bug#49809: [PATCH] Add macro 'pcase-setq', Stefan Monnier, 2021/08/05
- bug#49809: [PATCH] Add macro 'pcase-setq', Stefan Monnier, 2021/08/05
- bug#49809: [PATCH] Add macro 'pcase-setq', Michael Heerdegen, 2021/08/05
- bug#49809: [PATCH] Add macro 'pcase-setq', Stefan Monnier, 2021/08/06
- bug#49809: [PATCH] Add macro 'pcase-setq', Michael Heerdegen, 2021/08/06
bug#49809: [PATCH] Add macro 'pcase-setq', Okam, 2021/08/06