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(Autoconf Language): Explain that

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``descriptions'' may not be double quotes.
(Quotation Rule Of Thumb): Likewise.
(Pretty Help Strings): Likewise; remove the wrong comment;
simplify the examples and improve their quoting.
This commit is contained in:
Paul Eggert 2004-11-22 23:31:56 +00:00
parent d134956a15
commit 39dc4d1039
1 changed files with 24 additions and 16 deletions
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40
doc/autoconf.texi
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@ -1068,6 +1068,12 @@ AC_COMPILE_IFELSE([[char b[10];]],, [AC_MSG_ERROR([you lose])])
@noindent
Voil@`a, you actually produce @samp{char b[10];} this time!
On the other hand, descriptions (e.g., the last parameter of
@code{AC_DEFINE} or @code{AS_HELP_STRING}) are not literals---they
are subject to line breaking, for example---and should not be double quoted.
Even if these descriptions are short and are not actually broken, double
quoting them yields weird results.
The careful reader will notice that, according to these guidelines, the
``properly'' quoted @code{AC_CHECK_HEADER} example above is actually
lacking three pairs of quotes! Nevertheless, for the sake of readability,
@ -8114,9 +8120,11 @@ your macros. If one or more words have disappeared in the M4
output, you need more quotes. When in doubt, quote.
However, it's also possible to put on too many layers of quotes. If
this happens, the resulting @command{configure} script will contain
this happens, the resulting @command{configure} script may contain
unexpanded macros. The @command{autoconf} program checks for this problem
by doing @samp{grep AC_ configure}.
by looking for the string @samp{AC_} in @file{configure}. However, this
heuristic does not work in general: for example, it does not catch
overquoting in @code{AC_DEFINE} descriptions.
@c ---------------------------------------- Using autom4te
@ -13042,22 +13050,22 @@ Expands into an help string that looks pretty when the user executes
Options}). The following example will make this clearer.
@example
AC_DEFUN([TEST_MACRO],
[AC_ARG_WITH([foo],
AS_HELP_STRING([--with-foo],
[use foo (default is NO)]),
[ac_cv_use_foo=$withval], [ac_cv_use_foo=no])
AC_CACHE_CHECK([whether to use foo],
[ac_cv_use_foo], [ac_cv_use_foo=no])])
AC_ARG_WITH(foo,
[AS_HELP_STRING(--with-foo,
[use foo (default is no)])],
[ac_cv_use_foo=$withval],
[ac_cv_use_foo=no])
@end example
Please note that the call to @code{AS_HELP_STRING} is @strong{unquoted}.
The second argument of @code{AS_HELP_STRING} is
not a literal, and should not be double quoted. @xref{Autoconf
Language}, for a more detailed explanation.
Then the last few lines of @samp{configure --help} will appear like
this:
@example
--enable and --with options recognized:
--with-foo use foo (default is NO)
--with-foo use foo (default is no)
@end example
The @code{AS_HELP_STRING} macro is particularly helpful when the
@ -13065,11 +13073,11 @@ The @code{AS_HELP_STRING} macro is particularly helpful when the
arguments, as shown in the following example.
@example
AC_DEFUN(MY_ARG_WITH,
[AC_ARG_WITH([$1],
AS_HELP_STRING([--with-$1], [use $1 (default is $2)]),
ac_cv_use_$1=$withval, ac_cv_use_$1=no),
AC_CACHE_CHECK(whether to use $1, ac_cv_use_$1, ac_cv_use_$1=$2)])
AC_DEFUN([MY_ARG_WITH],
[AC_ARG_WITH([$1],
[AS_HELP_STRING([--with-$1], [use $1 (default is $2)])],
[ac_cv_use_$1=$withval],
[ac_cv_use_$1=no])])
@end example
@end defmac