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Re: Old-style backquotes in cc-vars.el
From: |
Thien-Thi Nguyen |
Subject: |
Re: Old-style backquotes in cc-vars.el |
Date: |
Fri, 19 Oct 2007 09:29:05 +0200 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.0.97 (gnu/linux) |
() "Davis Herring" <address@hidden>
() Thu, 11 Oct 2007 10:41:11 -0700 (PDT)
Are we sure that it's okay to do all these evaluations at macro
expansion time -- that is, do any of them depend on runtime
things?
the original defcustom-c-stylevar evals so i thought continuing
the practice (regardless of the wisdom of the approach) would not
be harmful. in fact, in the most recent revision (tested a bit,
this time -- bonus!), VAL is no longer evalled.
And what is (eval (list 'identity foo))) supposed to
do differently than (eval foo)?
nothing, thanks for pointing this out -- i learn a lot from
nothing these days! i use the latter form now. the former was
fuzzy thinking and baby-in-the-background-crying induced.
please find below the revised defcustom-c-stylevar usurper.
substantial changes from the previous revision:
- docstring, reflecting best how i understand things
- new form `(declare (debug ...))'
- form `(radio ...)' is quoted
i consider all these changes bugfixes (and, thus, potentially
bug-harboring). please scrutinize them equally.
as mentioned before, this was (lightly) tested. i even went so
far as to invoke customize (shudder) and mouse around a bit. now
if you'll excuse me, i have to go wash my hands... :-/
[cc trimmed to ml]
thi
_____________________________________________________________
(defmacro defcustom-c-stylevar (name val doc &rest args)
"Define a style variable NAME with VAL and DOC.
More precisely, convert the given `:type FOO', mined out of ARGS,
to an aggregate `:type (radio STYLE (PREAMBLE FOO))', append some
some boilerplate documentation to DOC, arrange for the fallback
value of NAME to be VAL, and call `custom-declare-variable' to
do the rest of the work.
STYLE stands for the choice where the value is taken from some
style setting. PREAMBLE is optionally prepended to FOO; that is,
if FOO contains :tag or :value, the respective two-element list
component is ignored."
(declare (debug (symbolp form stringp &rest)))
(let* ((expanded-doc (concat doc "
This is a style variable. Apart from the valid values described
above, it can be set to the symbol `set-from-style'. In that case,
it takes its value from the style system (see `c-default-style' and
`c-style-alist') when a CC Mode buffer is initialized. Otherwise,
the value set here overrides the style system (there is a variable
`c-old-style-variable-behavior' that changes this, though)."))
(typ (eval (plist-get args :type)))
(type (if (consp typ) typ (list typ)))
(head (car type))
(tail (cdr type))
(newt (append (unless (plist-get tail :tag)
'(:tag "Override style settings"))
(unless (plist-get tail :value)
`(:value ,val))
tail))
(aggregate `'(radio
(const :tag "Use style settings" set-from-style)
,(cons head newt))))
`(progn
(c-set-stylevar-fallback ',name ,val)
(custom-declare-variable
',name ''set-from-style
,expanded-doc
,@(plist-put args :type aggregate)))))