Re: [bug-gnulib] libopts and gnulib?

[Bruno Haible]

Karl Berry wrote on 2006-02-13:
> Bruce Korb implemented a library for straightforward config file
> parsing (among other things).  We thought it would make sense to use it
> for GNU Hello, as an example of how it can be done.

How come so few programs use this libopts? Let me look at the syntax of
the various .??* files in my home directory.

  Plain list of keyword / value pairs:
    .RealNetworks_RealMediaSDK_60
    .RealNetworks_RealPlayer_60
    .RealNetworks_RealShared_00
    .appletviewer
    .asadminprefs
    .emiclockrc
    .flexlmrc
    .jaxe
    .kapptemplaterc
    .lincityrc
    .lynxrc
    .mailcap
    .mainactorrc
    .mcoprc
    .mh_profile
    .mtvrc
    .pinerc
    .tkcvs
    .urlview
    .xtalkrc

  X11 resources syntax:
    .Xdefaults
    .Xresources
    .acrorc
    .gv
    .nedit
    .weblink

  List of keyword / value pairs, with groups and parametrized keywords:
    .fvwmrc

  Nested groups of C-like compound statements with braces and semicolons:
    .balsarc

  Keywords with nested groups of C-like compound statements as values:
    .twmrc

  Parametrized keywords with nested groups of C-like compound statements as
  values:
    .gtkrc

  Windows ini syntax ([Group]s of Keyword=Value statements):
    .XaraLX
    .dmrc
    .kderc
    .realplayerrc
    .rpmfind
    .serc
    .sversionrc
    .thotrc
    .uitrc.*
    .yuditrc

  Other groups of keyword / value pairs:
    .autom4te.cfg

  Scripting language with at least conditional statements:
    shell:
      .bashrc
      .profile
      .xim
      .xinitrc
      .xserverrc
      .xsession
    Lisp:
      .clinit.cl
      .clisprc
      .sbclrc
      .talkrc
    Emacs-Lisp:
      .emacs
      .emacs-places
    vim:
      .exrc
      .vimrc
    C-like:
      .xcoralrc
    Other:
      .fpc.cfg
      .inputrc

  XML:
    .com.zerog.registry.xml
    .fonts.conf

  List of numbers:
    .clockrc

  Single identifier:
    .craftyrc
    .wmrc

  Other custom text format:
    .Bfs
    .DCOPserver
    .MCOP-random-seed
    .Xmodmap
    .addressbook.lu
    .dvipsrc
    .fonts.cache-1
    .gcalrc
    .gtk_qt_engine_rc
    .install4j
    .ispell_english
    .jazz
    .kermrc
    .lyxrc
    .mime.types
    .muttrc
    .nc_keys
    .rhosts
    .stonxrc
    .tex
    .valgrind.supp
    .viminfo
    .workmanrc
    .xmbdfedrc
    .zsh

  Binary format:
    .B.blend
    .Bfont
    .ICEauthority
    .Xauthority
    .esd_auth
    .fterc
    .tamaga.dat

It appears that different programs have wildly different needs in this area...

> Of course, it involves a new Autoconf macro to test whether the library
> is available.  And of course again, I don't want that macro to live in
> GNU Hello, since the goal is not Hello functionality, it's to be an
> example.  So I want it to be in a common place.  Which I guess is
> gnulib.

Why not have libopts itself provide and install the autoconf macro that
recognizes it?

> +AC_DEFUN([ag_FIND_LIBOPTS],
> +    [if test "X${ac_cv_header_autoopts_options_h}" == Xno
> +    then
> +      :
> +    else
> +      f=`autoopts-config cflags` 2>/dev/null
> +      test X"${f}" = X && f=`libopts-config cflags` 2>/dev/null

These xyz-config scripts have two flaws by design:

1) They don't support using the library with a different compiler than the
   one that built it. Indeed, the CFLAGS that are supported by one compiler
   are not supported by other compilers. Likewise for the "-Wl,-R/usr/lib"
   option reported as being present in `autoopts-config ldflags`: it does
   not work when the compiler is not gcc.

2) They expect to be found in PATH. I.e. in order to use packages installed
   in /foo/bar, it is no longer sufficient to set
     CPPFLAGS=-I/foo/bar/include
     LDFLAGS=-L/foo/bar/lib
   but it's also needed to set
     PATH=/foo/bar/bin:$PATH

Better use the AC_LIB_LINKFLAGS or AC_LIB_HAVE_LINKFLAGS macro from gnulib.
It doesn't have these flaws.

Bruno