Re: building a qt library

[Ralf Wildenhues]

Hello Craig,

a couple of comments to the configure.ac script and Makefile.am file you
posted:

* Craig Sanders wrote on Fri, Nov 28, 2008 at 01:58:56AM CET:
> 
> AC_INIT(
>         [simple_signal_emitter_autotools],
>         [0.0.1],
>         address@hidden,
>         [simple_signal_emitter_autotools])
> 
> # Inform aclocal and friends of where they can find additional
> # local Autoconf macros.
> 
> m4_include([./m4/bnv_have_qt.m4])

While this line is completely OK as it is, I would prefer doing it
differently:

- Generally, do not use `./' prefixes to files unless there is a
  specific reason to do so.  Why is that a good idea?  By this
  inclusion, the file m4/bnv_have_qt.m4 becomes a prerequisite of
  the configure script, and automake will be smart enough to notice
  this dependency and add the file to the configure regeneration
  rule in Makefile.in.  Now, however, most non-GNU make implementations
  do not identify `./FILE' with `FILE' in target or prerequisiste
  names.  So, in the hypothetical case that, for example, you have
  a rule to generate `m4/bnv_have_qt.m4', then it would not be
  updated before configure were out of date.  Omitting `./'
  would prevent this issue.
  Of course this is not likely to have an effect in this case,
  but it's a good rule to obey for portable makefiles.

- For third-party m4 files that provide extra macros, a good convention
  to use is to let aclocal find them automatically, and maybe even
  install updated versions into your package automatically.  The former
  can be achieved by
  -- adding `ACLOCAL_AMFLAGS = -I m4' to the toplevel Makefile.am;
      autoreconf will then pick this up when running aclocal; if you
     invoke it manually, you should add these flags as first options.

  The latter can be achieved with additionally
  -- adding AC_CONFIG_MACRO_DIR([m4]) to configure.ac,
  -- and then using `aclocal --install' (this requires Automake 1.10
     or newer)

  You can then just omit the m4_include line completely from
  configure.ac, and notice that aclocal will put such a line into
  aclocal.m4.

> AC_CONFIG_AUX_DIR(config)
> 
> AM_INIT_AUTOMAKE(
>                  [simple_signal_emitter_autotools],
>                  [0.1])

This format is the old-style invocation of AM_INIT_AUTOMAKE.
You don't need it: you are already using the new-style AC_INIT
which provides package name and version number.  Moreover, you
are using inconsistent version numbers in both.  Solution is
to use plain `AM_INIT_AUTOMAKE' without further arguments here.
You can then decide to add Options in the first argument if you
like.

> AC_CONFIG_SRCDIR(
>                  [./src/main.cpp])

Again, I'd omit the `./'

> AC_PROG_CC
> 
> AC_PROG_LIBTOOL
> 
> AC_PROG_CXX(
>             [${CXX}])

Why this argument?  Plain AC_PROG_CXX should be equivalent in semantics
(a default list of compiler names is tried unless $CXX is set).

> AC_PROG_LIBTOOL
> 
> BNV_HAVE_QT()
> 
> AC_OUTPUT([
>            Makefile
> ])


[ Makefile.am: ]

> bin_PROGRAMS   = main
> 
> main_MOC_FILES = ./moc_MySignalEmitter.cpp

Again, please omit leading `./'; several more instances.

> main_SOURCES   = ./src/main.cpp \
>                  ./src/MySignalEmitter.cpp \
>                  ${main_MOC_FILES}
> 
> main_CXXFLAGS  = ${QT_CXXFLAGS} -I${srcdir}/include
> 
> main_LDFLAGS   = ${QT_LIBS}
> 
> 
> CLEANFILES     = ${main_MOC_FILES}
> 
> # Inform make of how to handle C++ Header files (.hpp) that need
> # to be processed by the Qt Meta Object Compiler (moc).
> 
> .hpp.cpp:
>       @echo ""
>       @echo "----------------------------------------"
>       @echo "moc is creating the file : address@hidden"
>       @echo "... in directory         : address@hidden/"
>       @echo "... from input file      : $< "
>       @echo "$<"
>       @echo ""
>       ${QT_MOC} -o address@hidden $<