#LayerPrimitives aka allowing to add private package at runtime to a module ?

Andrew Dinn adinn at redhat.com
Thu Mar 16 17:19:59 UTC 2017

Hi Jochen,

If you want to comment on a thread on the expert group list then you
really need to post that comment to the observers or comments list.
Posting it here without any context is just going to confuse people who
don't read the expert group list

n.b. I am replying to the jigsaw-dev list rather than just to you
directly so as to clarify the provenance of your post for those who are
still as confused as I was until I found David's original note on the
expert group list.


Andrew Dinn
Senior Principal Software Engineer
Red Hat UK Ltd
Registered in England and Wales under Company Registration No. 03798903
Directors: Michael Cunningham, Michael ("Mike") O'Neill, Eric Shander

On 16/03/17 14:53, Jochen Theodorou wrote:
> On 16.03.2017 14:39, David M. Lloyd wrote:
> [...]
>> It's clear that modules are not to be treated like classes, because (for
>> example) circularity among modules is considered "bad" whereas
>> circularity among classes has been shown to be indispensable, and
>> classes within a class loader or module are loaded and resolved lazily
>> whereas modules are loaded and resolved aggressively, etc.  But I see
>> your point that only "special" citizens ought to mutate a module.  I
>> agree, but I do not think this should be limited to agents: containers
>> also have a similar need for similar reasons.
> and I would not simply limit this to containers as well. If you have a
> programming language runtime for example you have an element, that will
> have to do similar tasks to what Java internals will want to do.. for
> example proxies. But the big difference is, that we are not containing
> the classes we do the work for. The modules containing those might even
> be loaded already and instances of those classes may already exist.
> I was told an agent can mutate the module information. And I don't
> understand if an agent can do it, why a normal method cannot... or what
> makes a citizen "special" enough to be able to do it. On the contrary
> this discussion now gives me the impression an agent cannot mutate the
> module after it came into existence without duplicating classes. Clearly
> I had yet no time to actually try this :(
> bye Jochen

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