Sunday, July 31, 2011

Python Multi-Build for Python Extensions Packaging - Report 4

Hello,

This is the fourth report of my GSoC project for Debian. It has been a long time
since I wrote third report. So past four weeks a lot of things are implemented.

Firstly, I've changed tool's main script's name to py3build (removed .py suffix)
and make it executable so after you cloned my git repository you can use tool
with "./py3build".

I fixed a bug which occurs when the tool is invoked from somewhere except
its directory. If you invoke it like "./path/to/py3build/py3build" then the tool give
errors (f.e. could not find plugins etc.). Now this is fixed.

When I'm designing the API, I think if there is given build system (with
--system parameter) there is no need to invoke detect method but when
I'm writing autotools plugin, I realized that I need to learn which files are
exists and according to that information I'll invoke right thing (f.e. autoconf
or directly configure). So even if there is a given build system with --system
parameter its detect method invokes.

When I'm implementing plugins to tool, I need clean args (f.e. parameters
which are using with make clean) and install args (f.e. parameters with
make install) and I added it.

I added --dest-dir parameter this is passing to distutils plugin's root parameter.
In distutils plugin --install-dir parameter is passing as --install-platlib,
--install-purelib and --install-scripts so that maintainer can override it
with py3build's --install-args parameter.

Now, I implemented distutils, autotools, cmake plugins and working on
scons and packaging plugins. During the writing period of plugins I'm
testing them. After I finished these plugins I'm planning to write a patch
to dh and cdbs. After that I will write the tool and plugins for Python2.X.
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Sunday, July 3, 2011

Python Multi-Build for Python Extensions Packaging - Report 3

Hello,

This is the third report of my GSoC project for Debian. During last two weeks
I've done most of things about the main tool. Before that weeks I have been
working on project's API. API is almost finished. Still I find missing/wrong
parts during the coding and changing the API design.

Like I said, main tool's coding process is nearly finished. For now It is doing
its job for building Python3.X packages. You can find the source code at [1].

I also coded an example plugin (actually only return values) and plugins/__init__.py
file which contains like Base class, exception classes and plugin listing method.

When I started coding I realized that I need extra parameters. I've added --install-dir
parameter. You can specify the install directory if there is no install directory the tools
pretends that the install directory is "./debian/tmp". After that it checks whether if the
directory exists. If not it creates the directory.

I've changed py3build.py a bit. First, I've thought for every process I invoke py3build's
methods but they are redundant. I've removed them. Now they are called in main
method of py3build.

I use logging module for printing messages, errors etc.

get_build_system() method retieves list from plugins/__init__.py file. In that file there is
scan_for_plugins() method. It finds all plugins in plugins/ directory which files match for
"[a-zA-Z].py". It keeps the list in plugins_list variable and returns that. When I'm writing
scan_for_plugins() method I've read codes (f.e. [2]) about that and decided to name all
plugins' class name as *BuildSystem*. Now, detecting method works with that way.
(all plugins' class' are called BuildSystem) And I've changed base class name to
BuildSystemBase.

get_build_system() method is used by determine_build_system() method. If there is given
build system (by parameter) it tries to use that. If that build system is not usable then give
error and exits. If there is no given build system. It invokes get_build_system() and iterates
that methods return value which is a list. When iterating It create an instance of that build
system class (if can not create then it gives warning and skips that build system plugin)
and invokes detect method and append plugin name and detect method's return value to
the bs_list which contains plugin list which are available. And then sorts it. If there is error
while sorting list or there is no usable plugin then give error and exits. If there is multiple
highest detect values then lists that plugins and exists. (maintainer should select one of
these plugins to build extension.)

In main method, after getting arguments, it checks for verbose mode (or 'DH_VERBOSE'
environment variable) and sets log level (logging.DEBUG or logging.WARN)

If there is no given build_dir then it pretends it is "./".

After that It try to determine build system. If can not then prints error and exits.

And finally it starts to build extension. Firstly it checks if there is given version list. If not,
it uses default values and iterates build loop with that values.

First cleans, configures, builds (if there is no --test-only arg) and tests (if there is --test-only
arg or there is not --no-tests argument)

If there is error (raises plugin.Error) while invoking that method then prints error and exits.

In verbose mode tool prints every process. (like "configuring for PythonX.Y" etc.)

I've started writing a plugin for detecting *distutils*. For now, I only wrote its detect method. It
returns between 0-1.0 floating point value. If everything is OK it returns 1.0. Other methods does
nothing, only returns True but this week I'll finish this plugin and work for others.

For detecting distutils I've used the code at [3]. First I try to import that module if not, I've copied
required methods to plugins/_packaging.py file, I use them.

I don't use is_distutils() method directly. For give probability I invoke what it invokes and give them
a number. (f.e. _has_setup_py has 0.5, _has_pkg_info has 0.25 and _has_distutil_text has 0.25.
But if _has_setup_py returns False then detect method doesn't look other methods since they
require setup.py.)

For now that's all. See you at next time.


--
Mesutcan Kurt

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