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Re: master 6ebce84ff2b: Use t for non-nil default values in boolean defc
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From: |
Andreas Schwab |
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Subject: |
Re: master 6ebce84ff2b: Use t for non-nil default values in boolean defcustom declarations |
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Date: |
Tue, 02 May 2023 18:42:07 +0200 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) |
On Mai 02 2023, Robert Pluim wrote:
>>>>>> On Sat, 29 Apr 2023 13:23:42 +0200, Andreas Schwab
>>>>>> <schwab@linux-m68k.org> said:
>
> Andreas> On Apr 29 2023, Michael Albinus wrote:
> >> Mattias Engdegård <mattiase@acm.org> writes:
> >>
> >> Hi Mattias,
> >>
> >>> Use t for non-nil default values in boolean defcustom declarations
> >>>
> >>> +(defcustom viper-ms-style-os-p
> >>> + (not (not (memq system-type '(ms-dos windows-nt))))
> >>
> >> I'm just curious. Is there an advantage in using the (not (not ...))
> >> pattern?
>
> Andreas> Logically, (not (null ...)) would fit better.
>
> Andreas> (not is just an alias of null, so both are the same, of course).
>
> Yes, but (not (not ...)) maps nicely to '!!' in C
C doesn't have lists, and memq returns a list.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."