Java Platform Module System

Alex Buckley alex.buckley at
Mon May 1 21:06:41 UTC 2017

On 5/1/2017 1:48 PM, Stephan Herrmann wrote:
> On 01.05.2017 22:17, Alex Buckley wrote:
>>>>> - Another reference links "automatic modules" into JLS and will
>>>>> probably
>>>>>    link to ModuleFinder.of(Path...), right?
>>>> This text is also an informative note. Automatic modules are
>>>> discovered through ModuleFinder.of, sure, and they appear in other
>>>> places in the java.lang.module API too -- but none of that is the
>>>> point of the note. The point of the note is that the developer
>>>> doesn't specify 'requires' any differently for an automatic module
>>>> than for an explicit module.
>>> You make it sound as if automatic modules are relevant only at runtime.
>> Huh? The JPMS is assumed to be present at compile time, not just run
>> time. And automatic modules are a feature of the JPMS.
>> Alex
> Wait, are you expecting compilers to actually use the implementation behind
> ModuleFinder etc. in order to discover modules etc.?
> When you said
>    "The host system must use the Java Platform Module System (as if by
>     execution of the 'resolve' method of java.lang.module.Configuration)"
> I read this as requesting a compiler to perform the same operation as is
> specified in that API.
> Was the intention behind "must use the Java Platform Module System"
> to say s.t. like "must call methods of API in java.lang.module"?

A compiler is not required to physically invoke methods of the JPMS API. 
A compiler is required to determine which modules are read by each 
module *as if* by execution of Configuration::resolve, a Java SE API. 
The as-if term is common in Java SE Platform specs to mean "Implement it 
any way you like, but the result must agree with the result from <the 
thing after as-if>."


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