Re: Implied readability + layers

[Ali Ebrahimi]

Hi,

On Fri, Nov 6, 2015 at 4:09 AM, Alex Buckley <alex.buck...@oracle.com>
wrote:
>
>
> com.foo in layer2 requires com.baz in layer1, right? Yes.
>
> com.baz in layer1 uses types from com.bar in layer1, and NOT from com.bar
> in layer2, right? Yes.
>
> Therefore, com.foo uses types from com.bar in layer1 (as required by
> com.baz in layer1), right? Yes.
>
> I don't know what it means to say "we use com.bar@2 for layer2's
> modules". com.foo is in layer2, and you can make it read com.bar@2 via
> reflection, but otherwise com.bar@2 is not read by com.foo because
> com.baz doesn't know about it.

There is no need for reflection:
Please follow this sample and test it:

layer 1: com.baz and com.bar@1
---------------------------

module com.bar {//version1
    exports com.bar;
}

------------------

//Bar.java

package com.bar;
public class Bar {
    public String bar(){ return "bar1";}
}

module com.baz {
        requires com.bar;
        exports com.baz;
}

-----------------

//Baz.java

package com.baz;

import com.bar.Bar;
public class Baz {
    public String baz(){ return new Bar().bar();}
    public Bar bar(){
        return new Bar();
    }
}

layer 2: com.foo and com.bar@2
--------------------
 module com.bar {//version2

    exports com.bar;
}

-------------

//Bar.java

package com.bar;

public class Bar {
    public String bar(){ return "bar2";}
}

-------------

module com.foo {
        requires com.baz;

        exports com.foo;

}

-------------

Foo.java

package com.foo;

import com.bar.Bar;
import com.baz.Baz;

public class Main {
    public static void main(String[] args) {
        System.out.println(new Baz().baz());
        System.out.println(new Bar().bar());
    }
}


-------------------------

test code

public class Test {
    public static void main(String[] args) throws Exception {
        ModuleFinder finder1 = ModuleFinder.of(Paths.get("mods1"));
        Configuration cfg1 = Configuration.resolve(finder1,
Layer.boot(),ModuleFinder.empty(),"com.bar","com.baz");

        ModuleClassLoader cl1 = new ModuleClassLoader(cfg1);
        Layer layer1 = Layer.create(cfg1, m -> cl1);

        ModuleFinder finder2 = ModuleFinder.of(Paths.get("mods2"));
        Configuration cfg2 = Configuration.resolve(finder2,
layer1,ModuleFinder.empty(),"com.bar","com.foo");

        ModuleClassLoader cl2 = new ModuleClassLoader(cl1,cfg2);
        Layer layer2 = Layer.create(cfg2, m -> cl2);



        Module foo = layer2.findModule("com.foo").get();
        Module bar2 = layer2.findModule("com.bar").get();

        Module bar1 = layer1.findModule("com.bar").get();

        ClassLoader fooModuleLoader = layer2.findLoader("com.foo");
        Class<?> mainClass = fooModuleLoader.loadClass("com.foo.Main");

        Test.class.getModule().addReads(mainClass.getModule());
        Method mainMethod = mainClass.getMethod("main", String[].class);

        mainMethod.invoke(null, (Object)new String[0]);
    }

}

Result:

bar1
bar2

As you can see com.foo reads com.bar@2 without reflection.

I say this is puzzling since with almost the equivalent code I get
another result. If you want I can show for you in another post.

If you want I can send all test files to your mail?


-- 

Best Regards,
Ali Ebrahimi