@chapter Introduction
@flushright
-A physicist, an engineer, and a computer scientist were
-discussing the nature of God. Surely a Physicist, said the
-physicist, because early in the Creation, God made Light; and you
-know, Maxwell's equations, the dual nature of electro-magnetic
-waves, the relativist consequences@dots{} An Engineer!, said the
-engineer, because before making Light, God split the Chaos into
-Land and Water; it takes a hell of an engineer to handle that big
-amount of mud, and orderly separation of solids from
-liquids@dots{} The computer scientist shouted: And the Chaos,
-where do you think it was coming from, hmm?
+A physicist, an engineer, and a computer scientist were discussing the
+nature of God. ``Surely a Physicist,'' said the physicist, ``because
+early in the Creation, God made Light; and you know, Maxwell's
+equations, the dual nature of electromagnetic waves, the relativistic
+consequences@dots{}'' ``An Engineer!,'' said the engineer, ``because
+before making Light, God split the Chaos into Land and Water; it takes a
+hell of an engineer to handle that big amount of mud, and orderly
+separation of solids from liquids@dots{}'' The computer scientist
+shouted: ``And the Chaos, where do you think it was coming from, hmm?''
---Anonymous
@end flushright
@end example
You are now able to understand one of the constructs of Autoconf that
-has been continually misunderstood... The rule of thumb is that
+has been continually misunderstood@dots{} The rule of thumb is that
@emph{whenever you expect macro expansion, expect quote expansion};
-i.e., expect one level of quotes to be lost. For instance
+i.e., expect one level of quotes to be lost. For instance:
@example
AC_COMPILE_IFELSE([char b[10];],, [AC_MSG_ERROR([you lose])])
Voil@`a, you actually produce @samp{char b[10];} this time!
The careful reader will notice that, according to these guidelines, the
-"properly" quoted @code{AC_CHECK_HEADER} example above is actually
+``properly'' quoted @code{AC_CHECK_HEADER} example above is actually
lacking three pairs of quotes! Nevertheless, for the sake of readability,
double quotation of literals is used only where needed in this manual.
@c to split the macros in several files. In this case, Autoconf must be
@c told which files to load, and in which order.
@c
-@c @defmac AC_INCLUDE (@var{file}...)
+@c @defmac AC_INCLUDE (@var{file}@dots{})
@c @maindex INCLUDE
@c @c FIXME: There is no longer shell globbing.
@c Read the macro definitions that appear in the listed files. A list of
@c Can't use @ovar here, Texinfo 4.0 goes lunatic and emits something
@c awful.
@example
-AC_CONFIG_FOOS(@var{tag}..., [@var{commands}], [@var{init-cmds}])
+AC_CONFIG_FOOS(@var{tag}@dots{}, [@var{commands}], [@var{init-cmds}])
@end example
@noindent
should avoid
@example
-... && my_foos="$my_foos fooo"
-... && my_foos="$my_foos foooo"
+@dots{} && my_foos="$my_foos fooo"
+@dots{} && my_foos="$my_foos foooo"
AC_CONFIG_FOOS($my_foos)
@end example
and use this instead:
@example
-... && AC_CONFIG_FOOS(fooo)
-... && AC_CONFIG_FOOS(foooo)
+@dots{} && AC_CONFIG_FOOS(fooo)
+@dots{} && AC_CONFIG_FOOS(foooo)
@end example
The macro @code{AC_CONFIG_FILES} and @code{AC_CONFIG_HEADERS} use
@ovindex ECHO_C
@ovindex ECHO_N
@ovindex ECHO_T
-How to suppress the trailing newline from @code{echo} for
-question... answer reports:
+How does one suppress the trailing newline from @code{echo} for
+question-answer message pairs? These variables provide a way:
@example
echo $ECHO_N "And the winner is... $ECHO_C"
@end example
@noindent
-Some old and uncommon @code{echo} offer no means to achieve this, in
-which case @code{ECHO_T} is set to tab. You might not want to use it.
+Some old and uncommon @code{echo} implementations offer no means to
+achieve this, in which case @code{ECHO_T} is set to tab. You might not
+want to use it.
@end defvar
@defvar FFLAGS
You might wonder why @command{autoheader} is needed: after all, why
would @command{configure} need to ``patch'' a @file{config.h.in} to
produce a @file{config.h} instead of just creating @file{config.h} from
-scratch?
-
-Well, when everything rocks the answer is just that we are wasting our
-time maintaining @command{autoheader}: generating @file{config.h}
-directly is all that is needed.
-
-But when things go wrong, you'll thank the Autoconf team for
-@command{autoheader}...
+scratch? Well, when everything rocks, the answer is just that we are
+wasting our time maintaining @command{autoheader}: generating
+@file{config.h} directly is all that is needed. When things go wrong,
+however, you'll be thankful for the existence of @command{autoheader}.
The fact that the symbols are documented is important in order to
-@emph{check} that @file{config.h} makes sense.
+@emph{check} that @file{config.h} makes sense. The fact that there is a
+well defined list of symbols that should be @code{#define}'d (or not) is
+also important for people who are porting packages to environments where
+@command{configure} cannot be run: they just have to @emph{fill in the
+blanks}.
-The fact that there is a well defined list of symbols that should be
-@code{#define}'d (or not) is also important for people who are porting
-packages to environments where @command{configure} cannot be run: they
-just have to @emph{fill in the blanks}.
-
-But let's come back to the point: @command{autoheader}'s invocation...
+But let's come back to the point: @command{autoheader}'s invocation@dots{}
If you give @command{autoheader} an argument, it uses that file instead
of @file{configure.ac} and writes the header file to the standard output
leads to a permanent deadlock. Vendors don't want to break user's
existant shell scripts, and there are some corner cases in the Bourne
shell that are not completely compatible with a @sc{posix} shell. Thus,
-vendors who have taken this route will @emph{never} (OK... ``never say
+vendors who have taken this route will @emph{never} (OK@dots{}``never say
never'') replace the Bourne shell (as @command{/bin/sh}) with a
@sc{posix} shell.
@end quotation
It is worth noting that Zsh (but not Ash nor Bash) makes it possible
in assignments though: @samp{foo=`cd /zorglub` 2>/dev/null}.
-Most shells if not all (including Bash, Zsh, Ash) output traces on stderr
-including for sub shells. This might result in undesired content if you
-meant to capture the standard error of the inner command:
+Most shells, if not all (including Bash, Zsh, Ash), output traces on
+stderr, even for sub-shells. This might result in undesired content
+if you meant to capture the standard-error output of the inner command:
@example
$ ash -x -c '(eval "echo foo >&2") 2>stderr'
@end example
@noindent
-You'll appreciate the various levels of details...
+You'll appreciate the various levels of detail@dots{}
-One way out consists in grepping out uninteresting lines, hoping not to
-remove good ones...
+One workaround is to grep out uninteresting lines, hoping not to remove
+good ones@dots{}
@node File System Conventions, Shell Substitutions, File Descriptors, Portable Shell
@subsection File System Conventions
@noindent
and in fact it is even @emph{more} portable: in the first case of the
first attempt, the computation of @code{top_srcdir} is not portable,
-since not all shells properly understand @samp{"`... "foo"... `"}.
-Worse yet, not all shells understand @samp{"`... \"foo\"... `"} the same
-way. There is just no portable way to use double-quoted strings inside
-double-quoted backquoted expressions (pfew!).
+since not all shells properly understand @code{"`@dots{}"@dots{}"@dots{}`"}.
+Worse yet, not all shells understand @code{"`@dots{}\"@dots{}\"@dots{}`"}
+the same way. There is just no portable way to use double-quoted
+strings inside double-quoted backquoted expressions (pfew!).
@table @code
@item $@@
@end example
@noindent
-...but beware of the @samp{@}} bug from Solaris (see above). For safety,
+@dots{}but beware of the @samp{@}} bug from Solaris (see above). For safety,
use:
@example
@end example
Alas, negated character classes are probably not portable, although no
-shell is known to not support the @sc{posix.2} syntax @samp{[!...]}
+shell is known to not support the @sc{posix.2} syntax @samp{[!@dots{}]}
(when in interactive mode, @command{zsh} is confused by the
-@samp{[!...]} syntax and looks for an event in its history because of
+@samp{[!@dots{}]} syntax and looks for an event in its history because of
@samp{!}). Many shells do not support the alternative syntax
-@samp{[^...]} (Solaris, Digital Unix, etc.).
+@samp{[^@dots{}]} (Solaris, Digital Unix, etc.).
One solution can be:
@quotation
No, under some older flavors of Unix, leading @samp{//} is a special
-path name: it refers to a "super-root" and is used to access other
+path name: it refers to a ``super-root'' and is used to access other
machines' files. Leading @samp{///}, @samp{////}, etc. are equivalent
to @samp{/}; but leading @samp{//} is special. I think this tradition
started with Apollo Domain/OS, an OS that is still in use on some older
Don't use multiple regexps with @option{-e}, as some @code{grep} will only
honor the last pattern (eg., IRIX 6.5 and Solaris 2.5.1). Anyway,
-Stardent Vistra SVR4 @code{grep} lacks @option{-e}... Instead, use
+Stardent Vistra SVR4 @code{grep} lacks @option{-e}@dots{} Instead, use
alternation and @code{egrep}.
Make itself suffers a great number of limitations, only a few of which
being listed here. First of all, remember that since commands are
-executed by the shell, all its weaknesses are inherited...
+executed by the shell, all its weaknesses are inherited@dots{}
@table @asis
@item @code{VPATH}
If given, @var{language} specifies the language we just @emph{quit}. It
is a good idea to specify it when it's known (which should be the
-case...), since Autoconf will detect inconsistencies.
+case@dots{}), since Autoconf will detect inconsistencies.
@example
AC_LANG_PUSH(Fortran 77)
For instance:
@example
-@r{ ... AC_INIT, etc. ...}
+@r{ @dots{} AC_INIT, etc. @dots{}}
@group
# Checks for programs.
AC_PROG_CC
AC_PROG_GCC_TRADITIONAL
-@r{ ... more program checks ...}
+@r{ @dots{} more program checks @dots{}}
AC_CACHE_SAVE
@end group
# Checks for libraries.
AC_CHECK_LIB(nsl, gethostbyname)
AC_CHECK_LIB(socket, connect)
-@r{ ... more lib checks ...}
+@r{ @dots{} more lib checks @dots{}}
AC_CACHE_SAVE
@end group
AM_PATH_GTK(1.0.2,, (exit 1); exit)
AM_PATH_GTKMM(0.9.5,, (exit 1); exit)
@end group
-@r{ ... AC_OUTPUT, etc. ...}
+@r{ @dots{} AC_OUTPUT, etc. @dots{}}
@end example
@node Printing Messages, , Caching Results, Results
@c FIXME: Grmph, yet another quoting myth: quotation has *never*
@c prevented `expansion' of $1. Unless it refers to the expansion
-@c of the value of $1? Anyway, we need a rewrite here...
+@c of the value of $1? Anyway, we need a rewrite here@dots{}
The most common brokenness of existing macros is an improper quotation.
This section, which users of Autoconf can skip, but which macro writers
@end example
With this in mind, we can explore the cases where macros invoke
-macros...
+macros@dots{}
@node Quotation and Nested Macros, Quotation Rule Of Thumb, One Macro Call, Quoting
@example
@group
-if ...; then
+if @dots{}; then
AC_REQUIRE([SOME_CHECK])
fi
-...
+@dots{}
SOME_CHECK
@end group
@end example
But since there is a macro named @code{AC_SUBST_FILE}, it was just
impossible to @samp{AC_SUBST(FILE)}! In this case,
@code{AC_SUBST(@var{symbol})} or @code{_AC_SUBST(@var{symbol})} should
-have been used (yes, with the parentheses)...or better yet, high-level
+have been used (yes, with the parentheses)@dots{}or better yet, high-level
macros such as @code{AC_EXPAND_ONCE}.
No Autoconf macro should ever enter the user-variable name space; i.e.,
AC_DEFUN([AC_PATH_X],
[AC_MSG_CHECKING([for X])
AC_REQUIRE_CPP()
-@r{# ...omitted...}
+@r{# @dots{}omitted@dots{}}
AC_MSG_RESULT([libraries $x_libraries, headers $x_includes])
fi])
@end example
AC_DEFUN([AC_PATH_X],
[AC_REQUIRE_CPP()[]dnl
AC_MSG_CHECKING([for X])
-@r{# ...omitted...}
+@r{# @dots{}omitted@dots{}}
AC_MSG_RESULT([libraries $x_libraries, headers $x_includes])
fi[]dnl
])# AC_PATH_X
Synopsis:
@example
-./config.status @var{option}... [@var{file}@dots{}]
+./config.status @var{option}@dots{} [@var{file}@dots{}]
@end example
It configures the @var{files}, if none are specified, all the templates
@defmac AC_CHECKING (@var{feature-description})
@maindex CHECKING
-Same as @samp{AC_MSG_NOTICE([checking @var{feature-description}...]}.
+Same as @samp{AC_MSG_NOTICE([checking @var{feature-description}@dots{}]}.
@end defmac
@defmac AC_COMPILE_CHECK (@var{echo-text}, @var{includes}, @var{function-body}, @var{action-if-found}, @ovar{action-if-not-found})
projects / thirdparty / autoconf.git / commitdiff
