Use @exportS3Method for S3 registration

[jcheng5]

If requiring R >=3.6.0 is OK, I think you can use this simpler way of registering S3 methods whose generics live in Suggests/Enhances packages.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.09%. Comparing base (96f41d5) to head (79c0fdd).

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #103   +/-   ##
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  Coverage   99.09%   99.09%           
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  Files           8        8           
  Lines         551      551           
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  Hits          546      546           
  Misses          5        5           

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[shikokuchuo]

Thanks so much! I'll happily take the R 3.6 dependency for this simplification.

The previous code may have looked horrendous, but is actually extracted straight from the base registerS3method() / registerS3methods(). I suspect it is the registering of the onLoad hooks that may have ended up being a bit invasive.

In any case, this is a much cleaner solution.