[Zope3-dev] Re: Dealing with external dependencies

[Jim Fulton]

On Jul 19, 2007, at 1:09 PM, Philipp von Weitershausen wrote:

> 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 :).

I just realized this over the weekend and even then wanted to discuss  
it with some folks.

...

>
>> 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).

Agreed.

>
> Should the next zope.testbrowser simply depend on any version of  
> mechanize and ClientForm?

I hope so. :)

>
>>> [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...

My objection isn't to install them as eggs, I'm a big fan of eggs,  
I'm just mystified by installing them as develop eggs.  In any case,  
PJE tells me this is correct, so I need to deal with it.

Jim

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