things done during a successful run of

apt-build install pkg [pkg...] :

cd /var/cache/apt-build/build/

for each pkg {
    $pkg_version = "Candidate:" from apt-cache policy <pkg>
    $src_version = first "Verson:" from apt-cache show <pkg>
    $src_name = last "Source:" from apt-cache show <pkg> where "Version:" is $pkg_version
                  (actually, (new AptPkg::Source '/etc/apt/sources.list')->{<pkg>}->[xx]->{Package},
                   which should be the same thing)
    $deb_file = "<pkg>_$pkg_version_<i386 or whatever architecture>.deb";
                   ($pkg_version is taken without a possible <number>: ("Epoch") at the beginning)

    if /var/cache/apt-build/build/$deb_file exists and --rebuild was not given
    {
	    print "Package $pkg_name already built.";
	    push(@pkgs, $deb_file);
	    move_to_repository(@pkgs);
	    build_repository();
    }
    else, if /var/cache/apt-build/repository/$deb_file exists and --rebuild was not given
    {
	    print "Package $pkg_name already in repository.";
	    push @pkgs, $deb_file;
    }
    else 
    {
        push @pkgs, $deb_file;  

        apt-get @apt_args build-dep <pkg>
        apt-get @apt_args update   if --noupdate was not given
	apt-get @apt_args source <pkg>=$src_version

        $upver = $AptPkg::Config::_config->system->versioning->upstream($src_version)
        $maintver = [everything behind "$upver-" in $src_version, if anything]

           e.g. with $src_version = '2.8.20-3', $upver is 2.8.20, $maintver is 3

        # build($src_name, $upver, $maintver)

        cd /var/cache/apt-build/build/$src_name-$upver
        apply patch(es) specified with --patch <file>, if any
        dpkg-buildpackage -b -us -uc   (overridable with --build_command)
        debclean unless --nocleanup was given

        mv /var/cache/apt-build/build/*.deb /var/cache/apt-build/repository/
	#&build_repository;
        cd /var/cache/apt-build/repository/
        my $arch = $_config->get("APT::Architecture");

        (following cmds only run if respective files don't exist yet)
        ln -s . main
        ln -s . apt-build
        ln -s . dists
        ln -s . binary-<i386 or...>
        make_release_file()

        apt-ftparchive packages . | gzip -9 > Packages.gz

        cd /var/cache/apt-build/build


        if --remove-builddep was given,
           apt-get @apt_args remove <packages installed during apt-get
                                     @apt_args build-dep <pkg> above>

          TODO: the list of those packages is (or should be) filled
                into @builddep by sub builddep, but IMHO that fcn is
                buggy and fails to fill the @builddep array. Haven't
                tested it though

    }


}

if --build-only was not given
{
    apt-get @apt_args update  unless --noupdate was given
    apt-get -t apt-build @apt_args install pkg [pkg...]  (pkgs given on cmdline)
}



Most convenient call is probably

apt-build --noyes --noupdate --nocleanup install pkg [pkg...]

 (asks before deleting packages, doesn't run apt-get update, doesn't
  clean the object files after build)





tack:/usr/local/src# apt-build install libgtk2.0-0 libglib2.0-0 libpango1.0-0
-----> Installing build dependencies (for gtk+2.0) <-----
Reading package lists... Done
Building dependency tree... Done
The following NEW packages will be installed:
  chrpath gnome-pkg-tools
The following held packages will be changed:
  chrpath gnome-pkg-tools
0 upgraded, 2 newly installed, 0 to remove and 1238 not upgraded.
Need to get 29.9kB of archives.
After unpacking 160kB of additional disk space will be used.
E: There are problems and -y was used without --force-yes
E: Failed to process build dependencies
-----> Updating package lists <-----
Ign file: apt-build Release.gpg
Get:1 file: apt-build Release [89B]
Ign file: apt-build/main Packages
Get:2 http://tick testing Release.gpg [189B]
Get:3 http://tick unstable Release.gpg [189B]
Get:4 http://tick testing/updates Release.gpg [189B]
Get:5 http://tick etch Release.gpg [189B]
Get:6 http://tick sid Release.gpg [189B]
Get:7 http://tick testing Release.gpg [189B]
Ign http://tick binary/ Release.gpg
Ign http://tick source/ Release.gpg
Get:8 http://tick testing Release.gpg [189B]
Get:9 http://tick unstable Release.gpg [189B]
Hit http://tick testing Release
Hit http://tick unstable Release
Hit http://tick testing/updates Release
Get:10 http://tick etch Release [5560B]
Hit http://tick sid Release
Hit http://tick testing Release
Hit http://tick binary/ Release
Hit http://tick source/ Release
Hit http://tick testing Release
Hit http://tick unstable Release
Hit http://tick testing/main Packages
Hit http://tick testing/contrib Packages
Hit http://tick testing/non-free Packages
Hit http://tick testing/main Sources
Hit http://tick testing/contrib Sources
Hit http://tick testing/non-free Sources
Hit http://tick unstable/main Packages
Hit http://tick unstable/contrib Packages
Hit http://tick unstable/non-free Packages
Hit http://tick unstable/main Sources
Hit http://tick unstable/contrib Sources
Hit http://tick unstable/non-free Sources
Hit http://tick testing/updates/main Packages
Hit http://tick testing/updates/contrib Packages
Hit http://tick testing/updates/non-free Packages
Hit http://tick testing/updates/main Sources
Hit http://tick testing/updates/contrib Sources
Hit http://tick testing/updates/non-free Sources
Hit http://tick etch/main Packages
Hit http://tick sid/main Packages
Ign http://tick testing/main Packages
Ign http://tick binary/ Packages
Ign http://tick source/ Sources
Ign http://tick testing/non-free Packages
Ign http://tick unstable/non-free Packages
Hit http://tick testing/main Packages
Hit http://tick binary/ Packages
Hit http://tick source/ Sources
Hit http://tick testing/non-free Packages
Hit http://tick unstable/non-free Packages
Fetched 7161B in 17s (419B/s)
Reading package lists... Done
-----> Downloading source gtk+2.0 (2.8.20-3) <-----
Reading package lists... Done
Building dependency tree... Done
Need to get 18.4MB of source archives.
Get:1 http://tick testing/main gtk+2.0 2.8.20-3 (dsc) [2003B]
Get:2 http://tick testing/main gtk+2.0 2.8.20-3 (tar) [18.2MB]
Get:3 http://tick testing/main gtk+2.0 2.8.20-3 (diff) [184kB]
Fetched 18.4MB in 1m51s (165kB/s)
gpg: Signature made Sat 14 Oct 2006 09:23:45 AM CEST using DSA key ID 2B0920C0
gpg: Can't check signature: public key not found
dpkg-source: extracting gtk+2.0 in gtk+2.0-2.8.20
dpkg-source: unpacking gtk+2.0_2.8.20.orig.tar.gz
dpkg-source: applying ./gtk+2.0_2.8.20-3.diff.gz
-----> Building gtk+2.0 <-----
dpkg-buildpackage: source package is gtk+2.0
dpkg-buildpackage: source version is 2.8.20-3
dpkg-buildpackage: source changed by root <root@tack>
dpkg-buildpackage: host architecture i386
dpkg-buildpackage: source version without epoch 2.8.20-3
dpkg-checkbuilddeps: Unmet build dependencies: gnome-pkg-tools chrpath
dpkg-buildpackage: Build dependencies/conflicts unsatisfied; aborting.
dpkg-buildpackage: (Use -d flag to override.)
----> Cleaning up object files <-----
Cleaning in directory .
dpkg-checkbuilddeps: Unmet build dependencies: gnome-pkg-tools chrpath
You do not appear to have all build dependencies properly met.
If you have the pbuilder package installed, you can run
/usr/lib/pbuilder/pbuilder-satisfydepends as root to install the
required packages, or you can do it manually using dpkg or apt using
the error messages just above this message.
Error while building libgtk2.0-0!
Sorry, no package to install.
-----> Installing build dependencies (for glib2.0) <-----
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED:
  bittorrent dia dia-common gimp-python hplip python-cairo python-glade2 python-gtk2 python-gtk2-dev python-htmlgen python-matplotlib
  python-netcdf python-numeric python-numeric-ext python-numeric-tutorial python-pyogg python-pyopenssl python-pyvorbis python-scientific
  python-twisted python-twisted-conch python-twisted-core python-twisted-lore python-twisted-mail python-twisted-names python-twisted-news
  python-twisted-runner python-twisted-web python-twisted-words python-zopeinterface skencil sketch streamtuner tla-buildpackage
The following NEW packages will be installed:
  gnome-pkg-tools
The following held packages will be changed:
  bittorrent debhelper gnome-pkg-tools python-cairo python-central python-htmlgen python-netcdf python-numeric python-numeric-ext
  python-numeric-tutorial python-numpy python-numpy-ext python-pisock python-pyogg python-pyopenssl python-pyvorbis python-scientific
  python-support python-twisted python-twisted-conch python-twisted-lore python-twisted-mail python-twisted-names python-twisted-news
  python-twisted-runner python-twisted-web python-twisted-words python-zopeinterface skencil sketch tla-buildpackage
The following packages will be upgraded:
  debhelper python-central python-numpy python-numpy-ext python-pisock python-support
6 upgraded, 1 newly installed, 34 to remove and 1232 not upgraded.
Need to get 2226kB of archives.
After unpacking 63.8MB disk space will be freed.
E: There are problems and -y was used without --force-yes
E: Failed to process build dependencies
-----> Updating package lists <-----
Ign file: apt-build Release.gpg
Get:1 file: apt-build Release [89B]
Ign file: apt-build/main Packages
Get:2 http://tick testing Release.gpg [189B]
Get:3 http://tick unstable Release.gpg [189B]
Get:4 http://tick testing/updates Release.gpg [189B]
Get:5 http://tick etch Release.gpg [189B]
Get:6 http://tick sid Release.gpg [189B]
Get:7 http://tick testing Release.gpg [189B]
Ign http://tick binary/ Release.gpg
Ign http://tick source/ Release.gpg
Get:8 http://tick testing Release.gpg [189B]
Get:9 http://tick unstable Release.gpg [189B]
Hit http://tick testing Release
Hit http://tick unstable Release
Hit http://tick testing/updates Release
Get:10 http://tick etch Release [5560B]
Hit http://tick sid Release
Hit http://tick testing Release
Hit http://tick binary/ Release
Hit http://tick source/ Release
Hit http://tick testing Release
Hit http://tick unstable Release
Hit http://tick testing/main Packages
Hit http://tick testing/contrib Packages
Hit http://tick testing/non-free Packages
Hit http://tick testing/main Sources
Hit http://tick testing/contrib Sources
Hit http://tick testing/non-free Sources
Hit http://tick unstable/main Packages
Hit http://tick unstable/contrib Packages
Hit http://tick unstable/non-free Packages
Hit http://tick unstable/main Sources
Hit http://tick unstable/contrib Sources
Hit http://tick unstable/non-free Sources
Hit http://tick testing/updates/main Packages
Hit http://tick testing/updates/contrib Packages
Hit http://tick testing/updates/non-free Packages
Hit http://tick testing/updates/main Sources
Hit http://tick testing/updates/contrib Sources
Hit http://tick testing/updates/non-free Sources
Hit http://tick etch/main Packages
Hit http://tick sid/main Packages
Ign http://tick testing/main Packages
Ign http://tick binary/ Packages
99% [Working]                                                                                                                      24.4kB/s 0s-----> Downloading source glib2.0 (2.12.4-1) <-----
Reading package lists... Done
Building dependency tree... Done
Need to get 3857kB of source archives.
0% [Waiting for headers]-----> Building glib2.0 <-----
Can't chdir(glib2.0-2.12.4): No such file or directory at (eval 1) line 3
        main::__ANON__('glib2.0-2.12.4') called at /usr/bin/apt-build line 288
        main::build('glib2.0', 2.12.4, 1) called at /usr/bin/apt-build line 510
        main::install called at /usr/bin/apt-build line 82
tack:/usr/local/src#



use AptPkg::Config qw/$_config/;                    # see libapt-pkg-perl
use AptPkg::System qw/$_system/;                    #
use AptPkg::Version;
use AptPkg::Source;
use AptPkg::Cache;


x @{$_source->{'libgtk2.0-0'}};


$_system = $_config->system;
$_config->{quiet} = 2;
$_cache = new AptPkg::Cache;
$_version = $_system->versioning;
$_source = new AptPkg::Source '/etc/apt/sources.list';
$_pkg_infos = $_cache->packages;






above problem ("E: There are problems and....") reproduced:

tack:# apt-get --yes build-dep libgtk2.0-0
Reading package lists... Done
Building dependency tree... Done
The following NEW packages will be installed:
  chrpath gnome-pkg-tools
The following held packages will be changed:
  chrpath gnome-pkg-tools
0 upgraded, 2 newly installed, 0 to remove and 1238 not upgraded.
Need to get 29.9kB of archives.
After unpacking 160kB of additional disk space will be used.
E: There are problems and -y was used without --force-yes
E: Failed to process build dependencies
tack:#

?????
what "problems"??


tack:# apt-get build-dep libgtk2.0-0
Reading package lists... Done
Building dependency tree... Done
The following NEW packages will be installed:
  chrpath gnome-pkg-tools
The following held packages will be changed:
  chrpath gnome-pkg-tools
0 upgraded, 2 newly installed, 0 to remove and 1238 not upgraded.
Need to get 29.9kB of archives.
After unpacking 160kB of additional disk space will be used.
Do you want to continue [Y/n]?
Get:1 http://tick testing/main chrpath 0.13-2 [13.6kB]
Get:2 http://tick testing/main gnome-pkg-tools 0.7 [16.3kB]
Fetched 29.9kB in 6s (4417B/s)
(Reading database ... 300272 files and directories currently installed.)
Unpacking chrpath (from .../chrpath_0.13-2_i386.deb) ...
Unpacking gnome-pkg-tools (from .../gnome-pkg-tools_0.7_all.deb) ...
Setting up chrpath (0.13-2) ...
Setting up gnome-pkg-tools (0.7) ...

tack:#