[gentoo-dev] The future of ebuild

[Felipe Contreras]

Hi gentooists,

I've been reading news sites about some changes happening in Gentoo
and I thought it might be a good time to submit some ideas I've been
baking for several years.

I come from a Linux From Scratch background, I like the feeling of
knowing every single corner of my system and the fact that there isn't
anything that I don't want or need. However, typing every single
command by hand is far from ideal, so at first I started writing some
scripts and eventually I wrote a build system that suited my needs. I
did it in bash for several reasons.

After a while I realized bash wasn't exactly the best language to
write such thing. Mainly because:

a) The code ends up with a lot of stuff for handling strings properly
(like escaping sequences)
b) Error are difficult to handle since bash doesn't have exceptions
c) Persistent information is difficult to achieve (no database stuff)
d) Package information is difficult to fetch/store (no objects/struct)

A more featured language could allow for example: filtered output,
exception handling->state storage->resuming.

But the big deal is with the package definition, recently I learned
about Domain Specific Languages, and I think that is the best option.

A new dsl allows many interesting features in the package definition
itself like: inheritance, exceptions, arrays, hash tables, objects,
modules, documentation, information messages, etc.

Take this example:

package Binutils < Gnu
  definition
    @version = "2.17"
    @name = "binutils"
    super() # run the Gnu definition stuff

    @config_opts = "--disable-nls --with-sysroot=\"#{$sys_root}\"
--enable-shared --disable-multilib"
  end

  steps
    build
      cd #{$top_build_dir}
      mkdir -p #{@build_dir}
      cd #{@build_dir}
      :configure "script" => "../#{@dir}/configure", "opts" => @config_opts
      make configure-host
      make
    end

    install
      cd #{$top_build_dir}
      cd #{@build_dir}
      make install
    end
  end
end

This is based on an already working prototype made in Ruby, so it's
biased towards Ruby facilities.

I've tried different build systems: rpm, dpkg, autopackage.
Unfortunately I never tried ebuild because it was based on bash as far
as I could tell.

After almost a decade of using Linux I still haven't found a build
system that suits all my needs. AFAIK ebuild is the most advanced but
it's still relying on ancient technology (bash scripts) so there will
always be limitations despite the brilliant ideas.

The core of a distribution is the "packaging" system, and the core of
the packaging system is the building system, which has no reason not
to be distribution agnostic, and actually, packaging system agnostic.

Why not create a new build system with a state of the art programming
language, and an advanced DSL that actually other distributions could
use?

I would like to hear your opinions on this matter.

-- 
Felipe Contreras
-- 
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