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Re: emacs-26: `with-eval-after-load' docstring omission
From: |
Stefan Monnier |
Subject: |
Re: emacs-26: `with-eval-after-load' docstring omission |
Date: |
Sat, 17 Mar 2018 10:19:22 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) |
> (with-eval-after-load 'flycheck
> (push "npx" (flycheck-checker-get 'javascript-eslint 'command)))
>
> Debugger entered--Lisp error: (void-function \(setf\ flycheck-checker-get\))
> (\(setf\ flycheck-checker-get\) (cons "npx" (flycheck-checker-get
> 'javascript-eslint 'command)) 'javascript-eslint 'command)
Yes, in this specific case, flycheck could actually make it work by defining
a (setf flycheck-checker-get) function.
> What do we gain from byte-compiling the bodies of with-eval-after-load forms?
As mentioned before: cleaner semantics. Macro-expanding the body of
with-eval-after-load more lazily (which is the core of the problem
you're hitting) won't help you if you happened to write your code as:
(defun my-after-flycheck ()
(push "npx" (flycheck-checker-get 'javascript-eslint 'command)))
(with-eval-after-load 'flycheck
(my-after-flycheck))
> Maybe we can find a way to prevent macro-expansion issues and make the
> behavior more intuitive?
I'd suggest to start by trying to find a way to get the behavior you
want *without* relying on (with-)eval-after-load (which is fiddly in any
case for all kinds of reasons. It's a handy tool when you need it, but
if you need it I consider that it's usually a sign that there's
a problem elsewhere).
Of course, this may require changes in flycheck.
Stefan