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Re: Plist-put changes literal argument


From: Yuan Fu
Subject: Re: Plist-put changes literal argument
Date: Wed, 2 Sep 2020 19:59:38 -0400


> 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


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