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diff --git a/doc/source/whatsnew/0.7.100.rst b/doc/source/whatsnew/0.7.100.rst new file mode 100644 index 0000000..eda2764 --- /dev/null +++ b/doc/source/whatsnew/0.7.100.rst @@ -0,0 +1,211 @@ +What's New In python-apt 0.7.100 +================================ +Python-apt 0.7.100 is a new major release of the python bindings for the APT +package management libraries. It provides support for Python 3, new language +features and an API conforming to :PEP:`8`. + +Despite the many changes made in python-apt 0.7.100, the release still provides +backwards compatibility to the 0.7 series. This makes it possible to run your +old applications. + +This documents describes the important changes introduced since the release +of python-apt 0.7.10.3, starting with the first development release 0.7.90 +from April 2009. + +.. note:: + + Applications using the old API should be updated to the new API because + the old ones will be dropped in a future release. To build a python-apt + variant without the deprecated API, build it without the -DCOMPAT_0_7 + compiler flag. + +Support for Python 3 +-------------------- +Python-apt is the first Debian package to support the third major release of +Python. The port is straight forward and integrates as nicely in Python 3 as +the Python 2 builds integrate in Python 2. + +Please be aware that python-apt builds for Python 3 are built without the +compatibility options enabled for Python 2 builds. They also do not provide +methods like :meth:`has_key` on mapping objects, because it has been removed +in Python 3. + +Python 3 support may be disabled by distributions. + +Real classes in :mod:`apt_pkg` +------------------------------ +The 0.7.100 release introduces real classes in the :mod:`apt_pkg` extension. This +is an important step forward and makes writing code much easier, because you +can see the classes without having to create an object first. It also makes +it easier to talk about those classes, because they have a real name now. + +The 0.7 series shipped many functions for creating new objects, because the +classes were not exported. In 0.7.100, the classes themselves replace those +functions, as you can see in the following table. + +.. table:: + + ===================================== ================================= + Function Replacing class + ===================================== ================================= + :func:`apt_pkg.GetAcquire` :class:`apt_pkg.Acquire` + :func:`apt_pkg.GetCache()` :class:`apt_pkg.Cache` + :func:`apt_pkg.GetCdrom()` :class:`apt_pkg.Cdrom` + :func:`apt_pkg.GetDepCache()` :class:`apt_pkg.DepCache` + :func:`apt_pkg.GetPackageManager` :class:`apt_pkg.PackageManager` + :func:`apt_pkg.GetPkgAcqFile` :class:`apt_pkg.AcquireFile` + :func:`apt_pkg.GetPkgActionGroup` :class:`apt_pkg.ActionGroup` + :func:`apt_pkg.GetPkgProblemResolver` :class:`apt_pkg.ProblemResolver` + :func:`apt_pkg.GetPkgRecords` :class:`apt_pkg.PackageRecords` + :func:`apt_pkg.GetPkgSourceList` :class:`apt_pkg.SourceList` + :func:`apt_pkg.GetPkgSrcRecords` :class:`apt_pkg.SourceRecords` + :func:`apt_pkg.ParseSection` :class:`apt_pkg.TagSection` + :func:`apt_pkg.ParseTagFile` :class:`apt_pkg.TagFile` + ===================================== ================================= + +Complete rename of functions, methods and attributes +----------------------------------------------------- +In May 2008, Ben Finney reported bug 481061 against the python-apt package, +asking for PEP8 conformant names. With the release of python-apt 0.7.100, this +is finally happening. + +Context managers for the :keyword:`with` statement +-------------------------------------------------- +This is not a real big change, but it's good to have it: +:class:`apt_pkg.ActionGroup` can now be used as a context manager for the +:keyword:`with` statement. This makes it more obvious that you are using an +action group, and is just cooler:: + + with apt_pkg.ActionGroup(depcache): + for package in my_selected_packages: + depcache.mark_install(package) + +This also works for :class:`apt.Cache`:: + + with cache.actiongroup(): # cache is an Instance of apt.Cache + for package in my_selected_packages: + package.mark_install() # Instance of apt.Package + +Yet another context manager is available for locking the package system:: + + with apt_pkg.SystemLock(): + # do your stuff here + pass + +There is also one for file based locking:: + + with apt_pkg.FileLock(filename): + # do your stuff here + pass + + +Unification of dependency handling +---------------------------------- +In apt 0.7.XX, there were three different return types of functions parsing +dependencies. + +First of all, there were :func:`apt_pkg.ParseDepends()` and +:func:`apt_pkg.ParseSrcDepends()` which returned a list of or groups (which +are lists themselves) which contain tuples in the format ``(package,ver,op)``, +whereas op is one of "<=",">=","<<",">>","=","!=". + +Secondly, there was Package.DependsListStr which returned a dictionary mapping +the type of the dependency (e.g. 'Depends', 'Recommends') to a list similar to +those of :func:`apt_pkg.ParseDepends()`. The only difference was that the +values ">>", "<<" of op are ">", "<" instead. + +Thirdly, there was SourceRecords.BuildDepends, which returned a simple list +of tuples in the format ``(package, version, op, type)``, whereas ``op`` was +the integer representation of those ">>", "<<" actions and ``type`` an integer +representing the type of the dependency (e.g. 'Build-Depends'). The whole +format was almost useless from the Python perspective because the string +representations or constants for checking the values were not exported. + +python-apt 0.7.100 puts an end to this confusion and uses one basic format, which +is the format known from Package.DependsListStr. The format change only applies +to the new functions and attributes, i.e. :attr:`SourceRecords.build_depends` +will now return a dict, whereas :attr:`SourceRecords.BuildDepends` will still +return the classic format. The functions :func:`apt_pkg.parse_depends` and +:func:`apt_pkg.parse_src_depends` now use the same values for ``op`` as +:attr:`Package.DependsListStr` does. + +Example:: + + >>> s = apt_pkg.SourceRecords() + >>> s.lookup("apt") + 1 + >>> s.build_depends + {'Build-Depends': [[('debhelper', '5.0', '>=')], + [('libdb-dev', '', '')], + [('gettext', '0.12', '>=')], + [('libcurl4-gnutls-dev', '', ''), + ('libcurl3-gnutls-dev', '7.15.5', '>=')], + [('debiandoc-sgml', '', '')], + [('docbook-utils', '0.6.12', '>=')], + [('xsltproc', '', '')], + [('docbook-xsl', '', '')], + [('xmlto', '', '')]]} + >>> s.BuildDepends + [('debhelper', '5.0', 2, 0), + ('libdb-dev', '', 0, 0), + ('gettext', '0.12', 2, 0), + ('libcurl4-gnutls-dev', '', 16, 0), + ('libcurl3-gnutls-dev', '7.15.5', 2, 0), + ('debiandoc-sgml', '', 0, 0), + ('docbook-utils', '0.6.12', 2, 0), + ('xsltproc', '', 0, 0), + ('docbook-xsl', '', 0, 0), + ('xmlto', '', 0, 0)] + +C++ headers +------------ +The 0.7.100 release introduces python-apt-dev which provides headers for +developers to provide Python support in the libapt-pkg-using application. + +Redesign of :mod:`apt_inst` +--------------------------- +The 0.7.100 series redesigns the :mod:`apt_inst` module to provide +more flexible classes replacing the older functions. The older functions +are still available in Python 2 builds, but are deprecated and will be +removed in the future. + +Other changes +------------- +This release of python-apt also features several other, smaller changes: + + * Reduced memory usage by making :class:`apt.Cache` create + :class:`apt.Package()` object dynamically, instead of creating all of + them during the cache initialization. + * Support to set the candidate version in :class:`apt.package.Package` + * Support for reading gzip-compressed files in apt_pkg.TagFile. + * Various changes to :mod:`apt.debfile` have been merged from gdebi. + +There have been various other changes, see the changelog for a complete list +of changes. + + +Porting your applications to the new python-apt API +---------------------------------------------------- +Porting your application to the new python-apt API may be trivial. You +should download the source tarball of python-apt and run the tool +utils/migrate-0.8 over your code:: + + utils/migrate-0.8.py -c myapp.py mypackage/ + +This will search your code for places where possibly deprecated names are +used. Using the argument ``-c``, you can turn colorized output on. + +Now that you know which parts of your code have to be changed, you have to know +how to do this. For classes, please look at the table. For all attributes, +methods, functions, and their parameters the following rules apply: + + 1. Replace leading [A-Z] with [a-z] (e.g DescURI => descURI) + 2. Replace multiple [A-Z] with [A-Z][a-z] (e.g. descURI => descUri) + 3. Replace every [A-Z] with the corresponding [a-z] (descUri => desc_uri) + +As an exception, refixes such as 'de' (e.g. 'dequote') or 'un' (e.g. 'unlock') +are normally not separated by underscores from the next word. There are also +some other exceptions which are listed here, and apply to any name containing +this word: **filename**, **filesize**, **destdir**, **destfile**, **dequote**, +**unlock**, **reinstall**, **pinfile**, **REINSTREQ**, **UNPACKED**, +**parse_commandline**. |