Dieter Maurer wrote:
During our latest discussion to put my most important Zope2 products
into a public repository, I have promissed to publish them on
PyPI instead. Yesterday, I started work to fulfill this promiss
and carefully read the PyPI related documentation -- to find
out, that it is not easy to publish Zope2 products.
As the name suggests, PyPI is for Python packages.
And Zope2 products rightfully are no Python packages:
When a Zope instance starts, it does potentially
expensive things for its products.
I have tiny Zope instances with a few inexpensive products
that start within a few seconds. And I have huge
Zope instances with lots of products which parse huge
XML files or have large message catalogs
and take half to one minute to start.
Definitely, I do not want that all my Zope
instances use the same products installed
via "setuptools" somewhere under the central "site-packages".
My current ideas towards a solution:
We define a package prefix for Zope2 products, e.g. "zope2.products".
-1 to more magic namespaces!
Zope2 products are published to PyPI as "<prefix>.<productname>".
We already have that. Products.*.
Basically, on Zope 2 trunk (and in 2.11), we've made
Products/__init__.py declare Products.* as a namespace package. That
means that you can package up an egg that uses this namespace package
and upload it to the cheese shop. Several of the Plone packages, e.g.
http://cheeseshop.python.org/pypi/Products.CMFDynamicViewFTI/3.0, do this.
We extend the Zope2 configuration with an option "additional-products"
which lists the products used by the instance that are not
at a standard place -- such as those installed by "setuptools"
I really don't see the need for this kind of complication. I would never
install a Products.* package into the global python interpreter. That's
a recipe for pain and incompatibility. Instead, I'd use zc.buildout or
virtualenv to have a sandbox for these eggs.
see http://plone.org/documentation/tutorial/buildout and
http://martinaspeli.net/articles/python-package-management.
Secondly, we already have something like additional-products, in that
for packages outside the Products.* namespace, we do not automatically
read ZCML, call initialize() and so on. Instead, we require that:
- the package's ZCML is explicitly pulled in, either via a ZCML slug,
or via an include from another ZCML file which is explicitly (or
implicitly, if it's in Products/*) parsed.
- the package uses the <five:registerPackage /> directive to declare
the package a Zope 2 product, which causes its initialize() function to
be called at the appropriate time.
Note that anything in Products.*, whether eggs in that namespace package
or plain directories in e.g. $INSTANCE_HOME/Products, behave as they
always have: ZCML is auto-loaded by Five, initialize() is always called.
Martin
--
Acquisition is a jealous mistress
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