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<div class="moz-cite-prefix">On 31/01/2024 07:47, Piotr P. Karwasz
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAFmygFYHgOFszk0nVZW1ctPJwf3XdgOAX=W6W+SchHKnq4-VGQ@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">Hello,
The `requires` instruction can have two qualifiers `static` and
`transitive` that separately make perfect sense. For a module `foo`:
* `requires static bar;`, makes resolution of the `bar` module
optional at runtime,
* `requires transitive bar;`, allows each module that reads `foo` to
also read `bar`. As far as I understand this means that `bar` must be
present at both compile time and runtime.
There is however a third option allowed:
```java
module foo {
requires static transitive bar;
}
```
</pre>
</blockquote>
It may be surprising but they do work together. If bar is resolved
then foo will read bar. If there is another module baz that requires
foo (and doesn't explicitly require bar) then baz will read foo, and
if bar is resolved, then baz will read bar.<br>
<br>
<br>
<blockquote type="cite" cite="mid:CAFmygFYHgOFszk0nVZW1ctPJwf3XdgOAX=W6W+SchHKnq4-VGQ@mail.gmail.com">:<span style="white-space: pre-wrap">
</span>
<pre class="moz-quote-pre" wrap="">
We often end up with such directives, when using the
`bnd-maven-plugin`, which maps the OSGi `resolution:=optional`
directive to `static` and the `uses:=...` directive to `transitive`.
If we mark a package as optional, but the package uses public types
from `bar`, we end up with `static transitive`.
Is this a bug of the plugin or does `static transitive` have a meaning?
</pre>
</blockquote>
I think it's more of a case that it is fragile for modules like foo
to have bar types foo API signatures. `requires static` is okay for
things like annotations with a retention policy of "source" but
going beyond that means giving up a bit on reliable configuration.
In the example, foo probably has a reflection guard and is careful
in their use of bar types. However, foo's user if baz and the
maintainers of baz are unaware of these shenanigans. This creates a
risk that baz code will get a CNFE at runtime.<br>
<br>
-Alan<br>
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