Revisit additional builder support

[jdknight]

Was just re-checking support with sphinx-note's strike with sphinxcontrib-confluencebuilder and noticed it is not working as expected. It looks to have been not working since v1.2 release due to the changes from #2 (specifically, 3ec9e3c). While sphinxcontrib-confluencebuilder does have the translation support to handle a strike node (as mentioned in #7 (comment)), since the role will not generate a strike node for unsupported builders, there will be no strike node to translate for this (or other builders).

It appears to me that the internal fallback was made to avoid docutil's developer strict-node check from failing. It appears the only way another extension can flag support for the node type is to manipulate a global supported builders list (#7), which does not feel like a "right" approach.

A suggestion, if desired, is maybe add an attribute flag that third-party builders can set to hint support for a given node type. For example, we added support for Sphinx's linkcode extension to allow external builders hint support using a supported_linkcode attribute. Maybe this extension could add support for a supported_sphinxnotes_strike attribute, where a third-party extension could define something such as:

class ConfluenceBuilder(Builder):
    supported_sphinxnotes_strike = True
    ...

And maybe sphinx-note's strike extension could adjust the check to something such as:

    builder = env.app.builder
    if not isinstance(builder, tuple(SUPPORTED_BUILDERS)) and \
            not getattr(builder, 'supported_sphinxnotes_strike', None):
        ...

[SilverRainZ]

Thanks for your suggestion. IMO there is no difference in essence between adding a flag to the builder and adding the builder to a global list.

As strike is a quite simple extension and it only requires the builder to implement visit/depart method of one node. Maybe we can check whether the strike node has a corresponding handler in Sphinx.registry.translation_handlers. What do you think?

[SilverRainZ]

Hello @adamtheturtle , what do you think of this?

[adamtheturtle]

I think that the whole concept of a "supported builder" with a fallback is best removed from this extension.