[Zope3-dev] directory hierarchy proposal

[holger krekel]

Jim Fulton wrote:
> holger krekel wrote:
> > Jim Fulton wrote:
> >>>What about the convention that namespace package __init__.py say something
> >>>like this:
> >>>
> >>># this is a namespace package, please keep  __init__.py empty of code
> >>>
> >>>This way anybody tempted to add stuff to an __init__.py where they shouldn't
> >>>will be made aware immediately that they shouldn't do that.
> >>>
> >>This is a good idea, It will need to be modified slightly, since it will
> >>contain some boilerplate code to knit all directories of the same name on the
> >>Python path into a single logical module.
> >>
> > 
> > I am bit uneasy about implicitly collecting modules from several places into
> > one namespace package. 
> 
> Why? The point is to separate physical organization, directories, from logical
> organization, the package.

My main concern is basically that in a more complex (e.g. developer's setup)
you have two modules with the same name in your pythonpath.
PYTHONPATH ordering are a source for many problems on c.l.py. 
The namespace-collecting mechanism would make it worse, i suspect. 

>  > In which places would a namespace package look?
> 
> This is described above. I'll give a detailed example.
> Now, suppose my Python path was something like:
> 
> 
>    [''
>     '/usr/local/python/latest/lib/python2.2',
>     '/usr/local/python/latest/lib/python2.2/plat-linux2',
>     '/usr/local/python/latest/lib/python2.2/lib-tk',
>     '/usr/local/python/latest/lib/python2.2/lib-dynload',
>     '/usr/local/python/latest/lib/python2.2/site-packages']
> 
> Now, I could install a zope package in in
> '/usr/local/python/latest/lib/python2.2/site-packages'
> 
> that contained, say, zope.pagetemplates.
> 
> I could also have a zope package in the current directory that contained
> zope.security.
> 
>  From Python, I'd be able to:
> 
>    from zope.pagetemplates import PageTemplate
>    from zope.security.checker import ProxyFactory
> 
> because the two physical zope directories would be merged
> into a single package.
> 
> > How is this configured? 
> 
> First, note that packages can define their own package-specific
> paths.  By default, a package path contains only the package directory,
> but it can be changed to include additional directories.
> 
> Each zope package __init__ file would have a bit of boilerplate code
> that would include all zope directories in sys.path:
> 
>    # Boilerplate code that combines all zope directories in sys.path
>    import sys, os
>    __path__ = [os.path.join(p, 'zope') for p in sys.path]

thanks for the explanation.  IMO without further checks (e.g. warnings for
duplicate names in different locations) this can be very confusing 
especially if you are remotely analyzing a customer problem who might
have installed lots of stuff and has a path with many items.

regards,

    holger