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Re: Warning: `mapcar' called for effect; use `mapc' or `dolist'
From: |
Dan Nicolaescu |
Subject: |
Re: Warning: `mapcar' called for effect; use `mapc' or `dolist' |
Date: |
Mon, 22 Oct 2007 13:07:40 -0700 |
Reiner Steib <address@hidden> writes:
> On Mon, Oct 22 2007, Katsumi Yamaoka wrote:
>
> >>>>>> Dan Nicolaescu wrote:
> >> The subject is about a new warning produced by the byte
> >> compiler. There's a lot of those for gnus.
> >> Assuming that all emacs versions that gnus wants to support have
> >> either mapc or dolist, can somebody please take care of these
> >> warnings?
> >
> >> Thanks
> >
> > With No Gnus v0.7 I did `cd lisp; make warn' and tried replacing
> > of `mapcar' with `mapc', `dolist', or `while' loops for a while,
> > and realized it's not easy and not safe. Ones who do it will
> > need to study what things using `mapcar' do in all cases. For
> > instance, `mapcar' used in `gnus-group-highlight-line' cannot be
> > replaced with `mapc' even if the compiler warns it.
>
> Could the byte-compiler be improved not to warn about such cases?
> Here's the relevant code:
>
> (defun gnus-group-highlight-line ()
> "Highlight the current line according to `gnus-group-highlight'."
> (let* ([...]
> (mailp (apply 'append
> (mapcar
> (lambda (x)
> (memq x (assoc (symbol-name
> (car (or method gnus-select-method)))
> gnus-valid-select-methods)))
> '(mail post-mail))))
> (level (or (gnus-info-level info) gnus-level-killed))
It seems that `mailp' is not used in that function. Adding a use for
it makes the warning go away...
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Reiner Steib, 2007/10/22
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist',
Dan Nicolaescu <=
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Reiner Steib, 2007/10/22
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Miles Bader, 2007/10/22
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Richard Stallman, 2007/10/23
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Miles Bader, 2007/10/23
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Richard Stallman, 2007/10/23
- Re: Warning: `mapcar' called for effect; use `mapc' or `dolist', Richard Stallman, 2007/10/23
- Message not available
- Risky variables in Gnus (was: Warning: `mapcar' called for effect; use `mapc' or `dolist'), Reiner Steib, 2007/10/27
- Re: Risky variables in Gnus (was: Warning: `mapcar' called for effect; use `mapc' or `dolist'), Richard Stallman, 2007/10/27