Package Organization (was Re: [Zope3-dev] Voting on Schema design)

[Jim Fulton]

Barry A. Warsaw wrote:
>>>>>>"JF" == Jim Fulton <jim@zope.com> writes:
...


> My mythical application (or Zope Product) has the following:
> 
>     from Zope.PackageA.ModuleA import ClassA
>     from Zope.PackageB.ModuleB import ClassB
> 
> with a directory layout like this:
> 
>     .../patha/Zope/PackageA/ModuleA.py
>     .../pathb/Zope/PackageB/ModuleB.py
> 
> Say ".../patha" is "<zopehome>/lib/python"
> and ".../pathb" is "<pythoninstall>/Lib/site-packages"
> 
> My application wants these packages from different locations because,
> while the version of PackageA that comes with Zope 3.x is fine for my
> purposes, I need the newer (independent) version of PackageB, which
> I've installed in my site-packages.
> 
>     JF> Well, if you want to sprad a package over multiple physical
>     JF> locations, that's easy enough to do. We do that in Zope 2
>     JF> now. Perhaps Python could provide a mechanism to make this
>     JF> easier. For example, it might be nice if packages could
>     JF> contain meta-data that would tell Python to search for
>     JF> multiple package directories along the Python path,
> 
> The one thing you don't want is for this mechanism to be dependent on
> search order, because it might be very difficult to get Python to
> search .../patha/Zope before .../pathb/Zope.

Why? The seach order should be governed by sys.path, just as for any
module search.

Would you want a different search order that sys.path?

BTW, I intent for ZopeProducts to work just this way. You'll be able to put
ZopeProducts diorectories in any directory in your search path and subpackages
will be looked up in search-path order. Again, it would be nice if Python
provided a way to automate this pattern.

Jim

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