Ordering of versions

[Neil Bartlett]

Brian,

You're right that a module need not be compared against other modules
for versioning purposes. But for this idea to work, each module would
have to provide its own implementation of a Version class, which has a
number of very challenging implications. First, where would that class
be loaded from?

It could not be loaded from the module itself because it is needed at
build, install and resolve time, i.e. well before any class from the
module could possibly be executed. So it would have to be loaded via
some means external to or alongside the module system. Then how would
the implementation of the Version itself be evolved? Suppose I found a
bug in my compareTo() method, how would I provide a fix to the bug?
Potentially each version of a module would end up with its own version
*scheme*, which would be nonsense.

The whole idea reminds me of the "module resolution scripts" that were
suggested back in the days of JSR 277. They would have been a disaster
as well, not least because they would have made it impossible to
statically reason about the dependency graph.

So, I don't think any reasonable module system can allow each module
to decide version *ordering* arbitrarily. There has to be one ordering
rule used by all modules. I would also like there to be one set of
semantics for version bumps in each segment... but I can see that the
chances of getting that in the Java 8 Module System are currently
slim.

Regards,
Neil

On Mon, Nov 14, 2011 at 4:04 PM, Brian Pontarelli <brian at pontarelli.com> wrote:
> It seems to me that the version scheme for a single module only impacts that module and not its dependencies. When the dependency graph is completely built and then traversed, modules are compared based on their scheme with all the other instances of themselves in the graph. Therefore, I don't think it impacts others at all.
>
> Thoughts?
>
> -bp
>
>
> On Nov 14, 2011, at 7:49 AM, Peter Kriens wrote:
>
>> Gili,
>> Can you explain how this would work when my modules use a different scheme than yours?
>>
>> Kind regards,
>>
>>       Peter Kriens
>>
>> On 13 nov. 2011, at 04:59, cowwoc wrote:
>>
>>>
>>> mark.reinhold wrote:
>>>>
>>>> Support such semantics, sure, but I'm not sure it should prescribe them.
>>>> OSGi and Maven have established some useful and widely-used conventions
>>>> around version semantics but I've seen developers and customers use all
>>>> sorts of other wild and woolly version schemes over the years.  I'm not
>>>> convinced that a standard Java module system should require people to
>>>> abandon such schemes, unless they're just really totally broken.
>>>>
>>>
>>> Mark,
>>>
>>> If at all possible, please consider allowing users to specify a
>>> Comparator<Version> (or Comparator<String> depending on your taste) on a
>>> per-module basis. This would allow users to use any versioning scheme they
>>> see fit.
>>>
>>> Gili
>>>
>>> --
>>> View this message in context: http://jigsaw-dev.1059479.n5.nabble.com/Ordering-of-versions-tp4970773p4988030.html
>>> Sent from the jigsaw-dev mailing list archive at Nabble.com.
>>
>
>