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From Luc Maisonobe <>
Subject Re: [VOTE] [math] top-level package name
Date Tue, 19 May 2009 21:14:25 GMT
Dimitri Pourbaix a écrit :
> Ted,
>> +0.  Possibly changing to +1 as I think about it more.
>> Dimitry,
>> Is there an argument that you could see would change your mind?  What
>> specifically causes your -1?  Convenience?  Elegance?
> Well, for me, the release number is not part of the name of a package
> (of anything in general) eventhough I agree the combination of both is
> what uniquely identifies the product.  Luc wants to add the "2" just to
> warn the users about the lack of backward compatibility.  That would
> simply add confusion.

This is not the reason why I proposed that. As I explained, the reason
came from another thread on this list where people said that when
incompatible changes are introduced on low level components that may be
used by several different middle level components, we can avoid jar-hell
by changing package names.

Consider the example Gilles provided a few hours ago:

* A (v1.0) depends on
   - B (v1.0)
   - Math (v1.2)

 * B (v1.0) depends on
   - Math (v1.2)

Now change only slightly his example by considering A needs to use Math
(v2.0) but the third party product B they rely upon does not publish an
updated version (say the project maintenance is busy doing something
other, or doesn't use the new features offered by V 2.0 and prefer
sticking to the old on). Then the incompatibilities between 1.2 and 2.0
creates problems for A's developers. Now extends this with tens of
libraries, you cannot rely on all libraries to be in sync all the time
with their dependencies.

With different packages names, the situation is simpler to handle: you
can have both libraries (in any order) in your classpath without
problems. You can have both 1.2 even hidden deep inside another jumbo
package and 2.0 without your code picking up the old classes when you
think it should pick the new ones ... This has happened only a few days
ago with commons-math.

> What is the policy in the other Apache projects?

It depends. Some are proposing to use this for all commons components,
some don't want to change package names.


> Regards,
>  Dim.
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