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From: Yuan Fu <casouri@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: Plist-put changes literal argument
Date: Wed, 2 Sep 2020 19:59:38 -0400	[thread overview]
Message-ID: <F64BE28B-8AA0-46E4-8B69-7C5B1D3C67F1@gmail.com> (raw)
In-Reply-To: <30E631BA-6845-43C1-AB5E-4C02C4F44780@gmail.com>



> On Sep 2, 2020, at 7:55 PM, Yuan Fu <casouri@gmail.com> wrote:
> 
> I found plist-put changes the literal argument I pass to a function:
> 
> (defun test ()
>  (test-2 '(:a b)))
> 
> (defun test-2 (form)
>  (print form)
>  (plist-put form :a 'c)
>  nil)
> 
> (progn (test) (test))
> 
> (:a b)
> 
> (:a c)
> nil
> 
> I thought Elisp is pass-by-copy? Is this expected?
> 
> P.S., (setf (alist-get )) does the same, I guess this IS expected?
> 
> Yuan

I also tried setcar, same result. So Elisp doesn’t copy arguments?

Yuan


  reply	other threads:[~2020-09-02 23:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-02 23:55 Plist-put changes literal argument Yuan Fu
2020-09-02 23:59 ` Yuan Fu [this message]
2020-09-03  0:18   ` Yuan Fu
2020-09-03  0:53     ` Noam Postavsky
2020-09-05 15:55     ` Philipp Stephani
2020-09-06 15:23       ` Yuan Fu
2020-09-05 15:53   ` Philipp Stephani

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