[hibernate-dev] OGM: CheckStyle and imports due to JavaDoc comments

[Sanne Grinovero]

On 31 July 2013 09:41, Gunnar Morling <gunnar at hibernate.org> wrote:
> 2013/7/31 Hardy Ferentschik <hardy at hibernate.org>
>
>> Hi,
>>
>> Personally I prefer to include a class via fully qualified name if it is
>> only used in the javadocs.
>> I think the readability does not suffer too much and adding an actual
>> import has actually
>> runtime consequences. We already had cases where a javadoc import caused a
>> hard link
>> between code which is otherwise decoupled.
>>
>
> WDYM exactly by "hard link" in this context? Is it about referencing a type
> from an optional dependency which might not be present at runtime?
>
> I just tried out this scenario (adding an import statement just for JavaDoc
> to a type which is not present at runtime) and still could execute the
> importing class without problems. Only when accessing the imported type in
> the actual code I'm getting a CNFE. But this might be specific to the VM in
> use, not sure.

It is VM specific indeed, and sensitive to situation as to prevent
circularity reference loading it never loads all imports aggressively,
but some might depending on the moon phase :-)
AFAIR IBM's JVM eagerly verifies class definition availability (but
does not necessarily initialize the class), and it wouldn't surprise
me even hotspot's behaviour could depend on specific situations and/or
obscure flags.. I don't really know how to write a comprehensive test
to showcase this but let's admit a simple test isn't enough to cover
all situations.

I'd expect more recent compilers to remove such dead imports, but
given it's not a big deal to remove these in the sources I'd rather be
safe: we had problems with such imports in the past.
I guess ideally we'd want IDEs to warn about it, I haven't seen an
option for this (other than checkstyle integration plugins).

Sanne

>
> So if you guys are concerned about this case then let's better keep it as
> is.
>
>
>
>>
>> Even the check stye documentation recommends against it in the
>> configuration
>> of Unused Imports -
>> http://checkstyle.sourceforge.net/config_imports.html#UnusedImports.
>>
>> --Hardy
>>
>>
>> On 31 Jan 2013, at 9:33 AM, Gunnar Morling <gunnar at hibernate.org> wrote:
>>
>> > Hi,
>> >
>> > Currently CheckStyle raises an error due to an "unused import" if a class
>> > imports types which are only referenced in JavaDoc comments. This issue
>> > occurs for instance when referring to a super type in the comments while
>> > only sub-types are used in the actual code:
>> >
>> >    /**
>> >     * This factory creates {@link Service} objects.
>> >     */
>> >    public class ServiceFactory {
>> >
>> >        FooService getFooService() { ... }
>> >    }
>> >
>> > Another example is "high-level" documentation on a central type of an API
>> > (e.g. its entry point) which refers to types actually used by specific
>> > parts of the API but not the entry point itself. In that case it can
>> still
>> > make sense to mention these types in the high-level docs.
>> >
>> > To work around the issue one could use the FQN in the JavaDoc or just
>> > format it as {@code}, but both makes up for less readable documentation
>> IMO.
>> >
>> > Personally I don't see a problem with this kind of import and thus
>> suggest
>> > to loosen that CS rule accordingly (it can be configured to take JavaDocs
>> > into account). WDYT?
>> >
>> > --Gunnar
>> > _______________________________________________
>> > hibernate-dev mailing list
>> > hibernate-dev at lists.jboss.org
>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>
>>
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