[Rd] How to modify dots and dispatch NextMethod

Tomas Kalibera tomas.kalibera at gmail.com
Thu Feb 22 12:39:31 CET 2018

On 02/22/2018 12:07 PM, Iñaki Úcar wrote:
> 2018-02-22 10:29 GMT+01:00 Tomas Kalibera <tomas.kalibera at gmail.com>:
>> The example is invoking NextMethod via an anonymous function, which is not
>> allowed (see documentation for NextMethod).
> Thanks for your response. I definitely missed that bit.
>> Normally one gets a runtime
>> error "'NextMethod' called from an anonymous function", but not here as the
>> anonymous function is called via do.call. I will fix so that there is a
>> runtime error in this case as well, thanks for uncovering this problem.
> Then I did well chosing this list! Please also note that you could
> take that anonymous function out of the method and name it, and the
> behaviour would be the same. So maybe this case should issue an error
> too.
I am not sure I understand how, but if you find a way to bypass the new 
check for an anonymous function (I intend to commit tomorrow), I will be 
happy to have a look if you provide a reproducible example.
>> I don't think there is a way to replace (unnamed) arguments in dots for
>> NextMethod.
> That's a pity. IMHO, it should be some mechanism for that, but dots
> are special in inscrutable ways.
> Anyway, for anyone insterested, I found a workaround:
> https://github.com/Enchufa2/dispatchS3dots#workaround
Even though technically this won't be too hard, I don't think NextMethod 
should be made any more complex than it is now. There should always be a 
way to implement special dispatch scenarios in R and your workaround 
shows it is possible specifically in your scenario.


>> Tomas
> Iñaki

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