Issue with qualified exports

[Peter Levart]

On 07/21/2016 10:55 AM, Alan Bateman wrote:
> On 21/07/2016 09:14, Peter Levart wrote:
>
>> Also,
>>
>> While it is expected that qualified exports are mostly used among 
>> modules that are more tightly coupled and are therefore more likely 
>> compiled together, some tools that invoke compiler (for example 
>> Maven), have a strategy to compile one module at a time, 
>> incrementally building the artifacts as the dependency tree instructs 
>> (because they must insert other building steps before or after 
>> compilation of each module, such as generating sources, etc...).
>>
>> So we have a problem here if such tool wants to 1st compile module A 
>> alone and then compile B which has a "requires" dependency on A, 
>> because A also has a qualified "export" dependency on B. An option 
>> like below could enable such separate compilation.
>>
> Single module compilation should be fine, assuming the source to the 
> referenced module is found (-modulesourcepath). We have exactly this 
> with the JDK build where modules are compiled in reverse topology 
> order. However, fair point about Maven projects, as qualified exports 
> are going to be problematic if they are separate projects as opposed 
> to a multi-module project.

They don't even have to be separate projects and you already have a 
problem when you step into the directory representing the module "A"  
and invoke mvn compile. In this case you are building just module A as a 
separate project. So each maven multi-module project is also a set of 
subsets of its modules and each such subset can be compiled in isolation...

The question is also should Maven then list module B as a dependency of 
A in A's pom.xml ? How can it otherwise find out the name of B's 
artifact? Jigsaw module names are not Maven artifact names and Maven 
does not allow circular dependencies!

Regards, Peter

>
> -Alan