question on exports to

[Alan Bateman]

On 01/06/2016 09:34, Jochen Theodorou wrote:
> :
>
> This now looks to me like this... GeneralInvoker will have to call 
> generalInvokerModule.addReads(myOtherLibModule), to enable to inspect 
> the classes from that library. It will then spawn a layer with a named 
> module, which contains the invocation code. This layerModule will 
> contain code to call layerModule.addReads(myOtherLibModule), so it can 
> access the classes in MyOtherLib if they are exported.... and since 
> that is not yet the case, I will have to cause MyOtherLib to call 
> myOtherLib.addExports("my.lib", layerModule).
>
> Which still means I cannot replace reflection completely, since it 
> does not have to cause MyOtherLib to call 
> myOtherLib.addExports("my.lib", layerModule). Or it means I still lack 
> understanding - which would not surprise me at all.
I don't wish to cause confusion in this thread but I think what you are 
looking for is:

1. MyOtherLib declares`requires GeneralInvoker`.

2. GeneralInvoker resolves "MyOtherLib" to create a configuration, that 
configuration is then instantiated as a module layer. There will be at 
least one module in that layer, maybe others if there are other 
dependences. GeneralInvoker will use findModule to locate the module 
named "MyOtherLib".

3. GeneralInvoker will use Module.addExports to export com.foo.gi to the 
runtime module MyOtherLib (from the thread then I gather than com.foo.gi 
is not exported, at least not unconditionally). This will allow the code 
in my.lib.SomeClassOfTheLibrary to invoke the public invoke method in 
com.foo.gi.TheInvoker.

4. The static initializer in my.lib.SomeClassOfTheLibrary will export 
my.lib to GeneralInvoker using Module.addExports. Again, I'm assuming 
that my.lib is not exported unconditionally. This one might be strange 
and non obvious but arises because qualified export aren't supported 
across layers. The "no forward reference" rule should be clear, it would 
be a security hazard. The "no back reference" (mean qualified exports to 
modules in parent layers) is a discussion point. It's useful in some 
scenario (like this one), not useful with static references because it 
would not make sense. This is a topic in itself and I don't wish to 
complicate your cage fight by going into this here.

With #4 then it allows GeneralInvoker to invoke the public methods in 
MyOtherLib's my.lib package.

As Alex noted, we need to write-up some of these "dynamic module" 
scenarios so there are pictures and examples to point at.

-Alan.