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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: Tue, 27 Feb 2018 15:58:05 -0500
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux)

>> Isn't that an irrelevant implementation detail? I don't see why it
>> should be documented.
> It is relevant, because the behavior isn't the same as 'eval'-ing
> a quoted form.

Yes, the behavior would be different if we quoted the expression and
passed it to `eval`, but in both cases it's an internal implementation
detail, and the relevant difference is the resulting change in
the semantics.

> But I don't think the documentation should be fixed; instead, I think the
> behavior should be changed :)

I think you're blinded by your current problem.
Try and remember the world of Coq.  Think about equivalences like

    (defun FUN () EXP)
    (with-eval-after-load FILE (FUN))
    (with-eval-after-load FILE EXP)

which are currently true (to the extent such things can be true in
Elisp where FUN can be redefined, of course) whereas

    (defun FUN () EXP)
    (eval-after-load FILE '(FUN))
    (eval-after-load FILE 'EXP)

[ Well, of course, this equivalence is actually true as well given the
  current compiler-macro, but I'm assuming above that we undo this
  compiler macro.  ]

IOW, the behavior you seem to want is semantically a good bit more messy.

In your case, you do want the quote because you need to delay
macro-expansion, but I think it's cleaner to solve this problem by
*explicitly* using a quote, rather than by relying on the messy
semantics of the macro/function you happen to be using.

E.g. your exact same problem could show up if you used, say,

    (add-hook 'flycheck-mode-hook ...)

instead of

    (with-eval-after-load ...)

but you wouldn't ask for a change in add-hook to "solve" your problem.


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