Hi Monty
So I hade to understand pandora-build last week, here are some
comments. I suppose this is as good a list as any to share this. I
leave it to you to break this into meaningful launchpad blueprints.
Relative to the autoconf mess that is your starting point, I see some
good and modular design going on in pandora. I can kind of understand
what you're trying to do. You ask for a very simple plugin.ini from
me. This makes me happy.
I didn't find a single line of documentation and no really useful code
comments either. This made me unhappy, especially as you were not
online last week. You can choose: Either you write documentation or
you don't go to Burning man.
Then for some specific usability comments:
build_conditional:
With the exception of memcached_* plugins, everyone that links to an
external lib does this:
build_conditional="$ac_cv_libv8" = "yes"
But $ac_cv_libv8 is an autoconf-internal (lower case) variable. So you
need to have secret knowledge of ./configure internals at this point.
Considering how clean and simple pandora-build is otherwise, this is a
real shame.
Why don't introduce:
# Needs libv8.so to build
external_dependency=libv8
# In case of missing dependencies, this module is excluded,
# but rest of build is allowed to continue
required=no
...which would then be transformed by pandora-build into
"$ac_cv_libv8" = "yes". You could then still leave build_conditional
as an advanced option for those that want to build their own condition
statement using any autoconf code they want.
I also have ldflags=${LTLIBV8} in plugin.ini. With the above change,
this could be automatically added by pandora-build too.
configure.ac magic:
Ok, so I proceeded to build my module that links against libv8.so. A
few more problems:
At first, .configure is not checking for libv8.so at all, so the above
build_dependency means my module is never built. With my proposed
changed above, you should make "required=" default to "yes", so that
in all such situations the build will stop and user will see what the
error is. required=no would then be a conscious action by the dev to
allow the build to proceed.
Even though there is no documentation, I'm a smart guy so after an
hour of random ls and grep, I realize I need to create a file
m4/pandora_have_libv8.m4 So I pick a simple one and make a copy and
replace libsomethingelse with libv8.
Nothing happens. Since I've never understood what all the layers in
autotools work, it takes me quite long to understand I need to add a
line in configure.ac to actually include the check for libv8. If
you're trying to create a build system for those of us who are unable
to understand autotools, I'd suggest:
Simple: pandora-build makes sure all tests in m4/ are run in
configure.ac. (Either by including them or erroring out with clear
message when you need to add something to configure.ac or somewhere
else.)
More advanced: a repository of tests (as copied from bzr branch
lp:pandora-build) exist in m4/test-repository/ and those you want to
run are symlinked from m4/enabled-tests/. Pandora-build makes sure all
tests in m4/enabled-tests/ are run in configure.ac.
gcc vs g++:
Drizzle is compiled as C++, and v8 is C++. But the pandora_have* tests
default to gcc (C) so my test fails and again build_conditional is
false. I eventually learn from google I must add AC_LANG_CPLUSPLUS to
my m4 file. I have no idea if/how this is possible, but it could be a
nice feature that if the project being built is C++, then either this
should have just worked or I would have gotten an error. Of course,
this is quite a rare problem to be honest, but I mention it for
completeness.
That was all. After 12 hours wasted by this kind of routine autotools
mess (helped by pandora-build, but made worse by no documentation) I
got my new drizzle plugin to build. Things are quite slow at work so I
don't mind, just wanted to give feedback.
henrik
--
henrik.i...@avoinelama.fi
+358-40-8211286 skype: henrik.ingo irc: hingo
www.openlife.cc
My LinkedIn profile: http://www.linkedin.com/profile/view?id=9522559
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