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Re: Elisp string function question
From: |
Jean Louis |
Subject: |
Re: Elisp string function question |
Date: |
Fri, 18 Jun 2021 15:28:05 +0300 |
User-agent: |
Mutt/2.0.7+183 (3d24855) (2021-05-28) |
* Ergus <spacibba@aol.com> [2021-06-18 15:19]:
> Hi:
>
> I just tried and this:
>
> (string-empty-p nil)
>
> returns nil. But nil is not an non-empty string. This forces to add some
> extra checks when using this function.
>
> Is this intended?
I got this too, and it is not for all cases suitable.
(defun string-blank-if-nil (s)
"Returns blank string for nil values"
(if (null s) "" s))
I often use this one as `nil' I sometimes wish to convert to empty string.
(string-blank-if-nil nil) ⇒ ""
(string-blank-if-nil "1") ⇒ "1"
Maybe that idea will help.
(defun string-or-empty-string (i)
"Returns empty string for nil"
(let* ((type (type-of i)))
(cond ((or (eql type 'integer)
(eql type 'float))
(number-to-string i))
((null i) "")
((eql type 'symbol) (prin1-to-string i))
((eql type 'string) i))))
Or that anything should be converted:
(string-or-empty-string nil) ⇒ ""
(string-or-empty-string 1) ⇒ "1"
(string-or-empty-string "ok") ⇒ "ok"
Or better idea:
(seq-empty-p nil) ⇒ t
(seq-empty-p "") ⇒ t
--
Jean
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Re: Elisp string function question, Stefan Monnier, 2021/06/18
Re: Elisp string function question, Michael Heerdegen, 2021/06/18
Re: Elisp string function question, Emanuel Berg, 2021/06/18