[Grok-dev] Re: Salt & z3c.autoinclude

[Ethan Jucovy]

On Fri, Mar 21, 2008 at 11:47 AM, Martijn Faassen <faassen at startifact.com>
wrote:

> I don't see that you should have to spell out the dotted name of the
> plugin package though: I see entry points contain a 'dist' attribute.
> Couldn't you use this information?


Ah, I never noticed that, but that looks good.  So scratch what I said about
containing no information about their provider.  :)  This should work fine.

 The right hand side needing something importable seems like a more
> troublesome problem. Then again, a plugin to an application will almost
> certainly have a dependency on that package, so a plugin for Plone will
> depend on Plone and import things from it. This means we could do the
> following:
>
> [z3c.autoinclude.plugin]
> target = package.plugged.into
>
> For plone (if it's in 'plone.app'):
>
> [z3c.autoinclude.plugin]
> target = plone.app


This concerns me, because I've already broken this assumption in my own code
while using my previous incarnation of salt.  I've actually found it useful
to be able to create a plugin package which *doesn't* technically require
the base platform, by putting the entire integration layer (declared
interface implementations, utility hookups) in ZCML.

On the other hand, I just did a quick hand test, and it appears that the
entry points aren't actually evaluated when the egg is installed.  So it's
only when you load() an entry point that the object it refers to must be
__import__able.  The entry point is only load()ed during execution of the
<includePlugins> directive for that platform.  So I think it's reasonable to
assume/enforce that the "target" package is present in the environment at
the time that the plugins are loaded.

All that said, I do still have a lingering hesitation about this format; it
just seems to be a bit of an abuse of entry points and a deviation from
their standard use.  It will work though (thanks for noticing the dist
attribute) so I'm willing to go along with it.

egj
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