On 19 Jul 2007, at 00:43 , Jim Fulton wrote:
On Jul 18, 2007, at 5:24 PM, Philipp von Weitershausen wrote:
Up until now we've been a bit sloppy when it came to egg
dependencies. Not specifying a version number or range basically
means that the code in question assumes it will work with any
future version of its dependency. Admittedly, setuptools doesn't
exactly make it easy to say "I depend on ZODB 3.8.x". Jim has
proposed to add a syntax to setuptools to support this nicely but
it's not there yet. So I guess we'll have to wait for that.
Heads up: I've come to think that depending on major revisions/
series isn't going to work. I'll say more about that in a separate
thread though.
Now you tell us :).
This was basically the equivalent of depending on a specific, well-
known working version of the external package.
I'm not sure what you mean here. The equivalent to what we did
before is to depend on specific versions at the *application*
level, by fixing a version in a application meta package or in a
buildout.
I guess.
I propose to do the same for the external dependencies we have. So
far I only count docutils as an actual egg dependency because
mechanize, ClientForm and twisted are still packaged up in the egg
that uses them (we should change that, too). I will therefore
change zope.app.renderer to depend on docutils==0.4, unless there
are objections.
Depending on specific versions in library packages (as opposed to
application packages or buildouts) is a recipe for disaster IMO.
As soon as 2 packages depend on different externals, then those 2
packages won't be usable together.
Good point.
In the long run, it might be better to only reuse packages that
offer some backward compatibility promises. Depending on a specific
version will make the dependent packages less reusable.
That makes sense. So, coming back to the real world: we have two
issues at hand. One is docutils, one is zope.testbrowser which
depends on mechanize and ClientForm (Adam is working on that, CCing
him as well).
With docutils I understand that it makes much sense to do this at
application level. With mechanize and ClientForm I'm not so sure.
What I *do* know is that the current situation (packaging them
*inside* the zope.testbrowser egg) isn't ideal (same goes for
twisted, btw).
Should the next zope.testbrowser simply depend on any version of
mechanize and ClientForm?
[1] This problem has bitten us over at Grok because apparently
Ubuntu has decided to deploy docutils 0.4.1 which doesn't seem to
actually exist anywhere and therefore confuses zc.buildout. See
https://bugs.launchpad.net/grok/+bug/126742.
I'm fairly sure that this has nothing to do with version numbers.
I suspect instead that it has something to do with the fact that
all distributions are now installed as "develop eggs" on ubuntu.
The locations of these eggs is actually site-packages. This sounds
very wonky to me, but Phillip Eby says it is normal.
It's actually necessary (to install these things as eggs) because
many packages nowadays depend on entry points. One could argue,
obviously, that their location (site-packages) isn't ideal...
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