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bug#31715: cl-incf and cl-decf error out when passed a nil-valued variab
From: |
Noam Postavsky |
Subject: |
bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset' |
Date: |
Tue, 05 Jun 2018 19:26:51 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Clément Pit-Claudel <clement.pitclaudel@live.com> writes:
> I'm not sure what to make of the result with SBCL and CLisp, since
> (incf x nil) also fails in both of them (whereas it works for us,
> since we can't distinguish nil and unspecified).
Oh, huh, I didn't think to check that case. Maybe we should just change
cl-incf to disintguish between nil and unspecified then.
(defmacro cl-incf (place &rest args)
"Increment PLACE by X (1 by default).
PLACE may be a symbol, or any generalized variable allowed by `setf'.
The return value is the incremented value of PLACE.
\(fn PLACE &optional X)"
(declare (debug (place &optional form)))
(let* ((got-x (= (length args) 1))
(x (car args)))
(if (symbolp place)
(list 'setq place (if got-x (list '+ place x) (list '1+ place)))
(list 'cl-callf '+ place (if got-x x 1)))))
>>> In the rest of Emacs there are lots of other examples. Many of them
>>> (for example semantic-find-tags-by-name or calendar-increment-month)
>>> seem to work when passed a nil-valued variable, but many others behave
>>> like cl-incf (for example gnus-summary-article-score).
>>
>> I don't think those are great examples of macros to emulate.
>
> Agreed, I was just collecting other examples, both in support and against my
> point.
Yeah, I just meant we can't really use those examples either to support
or argue against your point.
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Clément Pit-Claudel, 2018/06/04
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Noam Postavsky, 2018/06/04
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Michael Heerdegen, 2018/06/04
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Noam Postavsky, 2018/06/04
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Michael Heerdegen, 2018/06/04
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Clément Pit-Claudel, 2018/06/05
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Noam Postavsky, 2018/06/05
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Clément Pit-Claudel, 2018/06/05
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset',
Noam Postavsky <=
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Clément Pit-Claudel, 2018/06/05
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Michael Heerdegen, 2018/06/05
- bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Noam Postavsky, 2018/06/05
bug#31715: cl-incf and cl-decf error out when passed a nil-valued variable as 'offset', Clément Pit-Claudel, 2018/06/05