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 On Oct 18, 2019, at 5:15 PM, Stuart McCulloch <mccu...@gmail.com> wrote:
> 
> Any string apart from "default" or the empty string will work here - I
> happened to chose "core" because I viewed it as a core implementation.
> 
> Also a quick reminder that this is only needed when a component uses @Typed
> and wants to allow overriding, it's not necessary in any other situation -
> so in that sense "allowDefaultOverride" wouldn't be quite accurate. (See
> the javadoc in the patch for more detail.)
> 

Stuart,

There is an idiom like this used in the ReactorReader and the GraphBuilder 
where there are implementations of them in extensions out in the wild, and 
while those are not @Typed they use a @Named( “not-default” ) key pattern. If 
these components are intended to allow for custom implementations then a common 
way of doing this would be easier to understand. Something like @Named( 
“coreAllowingOverride” ) or @Named( “coreExtensionPoint” ) or whatever most 
appropriate. Right now there’s a bit of fiddly magic that works in Plexus with 
a lookup and Plexus with its annotations, and slightly different way with Sisu 
with @Inject annotations. So, sure, this particular case of requiring @Named( 
“core” ) to fix the case where you want to override a component with the 
implicit “default” key is required, but maybe something we should avoid and if 
it’s meant to be extended just have an explicit common pattern. I realize with 
DI you can override anything, but I don’t think being a little more explicit 
would hurt. The nuance of how the bindings work maybe you and Igor 
know/remember how it works, I had to use a debugger this afternoon :-)

Robert,

What’s overridden in polyglot is to be injected into Maven’s core is the 
ModelProcessor, not the ModelBuilder:

https://github.com/takari/polyglot-maven/blob/master/polyglot-common/src/main/java/org/sonatype/maven/polyglot/TeslaModelProcessor.java

The ModelReaders are injected into a manager within the TeslaModelProcessor, 
sure, but it’s the ModelProcessor being overridden which makes the magic happen 
in polyglot. When the ModelProcessor polyglot requires doesn't get injected 
it’s trying to use the XML-based model reader to read Kotlin which doesn’t work 
out so well. Trying to build a polyglot project without the extensions loaded 
in 3.6.1 yields the same result as trying to use 3.6.2 with a polyglot project: 
the same error which is a result of the right ModelProcessor not being found. 
You’ll see the the DefaultModelProcessor being used instead of the 
TeslaModelProcessor in the stack trace.

> PS. the reason DefaultModelProcessor needs to use @Typed is because it has
> an "interesting" interface hierarchy where ModelProcessor extends
> both ModelLocator and ModelReader, so it can act as both and delegate
> accordingly - but then it also asks to have a ModelLocator and ModelReader
> injected, which is where things get messy. If it had a cleaner hierarchy
> (ie. it wasn't asking to inject something that it also implements) then it
> wouldn't need @Typed and wouldn't then need the custom name.
> 

Agreed. Looks fixable and there are probably only two consumers in the world. 
Polyglot and https://github.com/qoomon/maven-git-versioning-extension where it 
was attempt to fix the problem in 3.6.2.

jvz

> 
> On Fri, 18 Oct 2019 at 20:35, Robert Scholte <rfscho...@apache.org> wrote:
> 
>> Hi,
>> 
>> the adjusted @Named annotation is on DefaultModelProcessor, not
>> DefaultModelBuilder.
>> They both implement the ModelBuilder interface, but the one that
>> extensions like to overwrite is the implementation of DefaultModelBuilder.
>> So I'd prefer to stick to "core" as proposed my Stuart.
>> 
>> thanks for the confirmation that this works,
>> Robert
>> 
>> On Fri, 18 Oct 2019 21:10:18 +0200, Jason van Zyl <jvan...@apache.org>
>> wrote:
>> 
>>> Hi,
>>> 
>>> As noted in Slack I think it would be more clear if we used something
>>> like
>>> 
>>> @Named( “allowDefaultOverride” )
>>> 
>>> vs
>>> 
>>> @Named( “core” )
>>> 
>>> As that expresses the intent and can be used anywhere it's allowed for
>> a
>>> client to override the default component.
>>> 
>>> The tests in polyglot all pass with this change, and I’m able to run
>>> polyglot example projects again, so I assume the Tycho POM-less are
>>> happy again as well but hopefully someone can verify.
>>> 
>>> Jason
>>> 
>>>> On Oct 18, 2019, at 2:04 PM, Robert Scholte <rfscho...@apache.org>
>>>> wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> with the help from Stuart McCulloch we've been able to provide a patch
>>>> for MNG-6765[1]
>>>> Please review and test.
>>>> 
>>>> thanks,
>>>> Robert
>>>> 
>>>> [1] https://issues.apache.org/jira/browse/MNG-67
>>>> [2]
>>>> 
>> https://github.com/apache/maven/commit/24e6c0ec0a87b6682513287a23c36db6996b874c
>>>> [3]
>>>> 
>> https://github.com/apache/maven/commit/53a70bc8543124569ee787725b2004bc92a681b6
>>>> 
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