On Wed, Mar 27, 2019 at 1:52 AM Abs Spurdle wrote:
>
> In the case of head.default(), it assumes that the object is a vector, or
> something similar.
>
No it doesn't. It assumes (ultimately) that x[seq_len(n)] is the correct
way to generate a "head" of something. Which is reasonable. That's
depe
> so instead of hitting utils:::head.function, it hits
utils:::head.default, which uses [ on the argument, causing the error.
I've thought about this some more.
And I still think that this is a bug.
If a generic has a default method, then that default method should be
guaranteed to work.
Or at le
Hi Abs,
This is because the class is "f", not c("f", "function") in your second
example. S3 method dispatch is doing what you (unintentionally, I presume)
asked it to do.
The S3 method which allows head to take functions is utils:::head.function.
S3 can only be expected to understand inheritance
(Using R 3.5.3).
I found bugs in head() and tail().
The following works:
> f = function () 1
> head (f)
1 function ()
2 1
However, the following does not:
> class (f) = "f"
> head (f)
Error in x[seq_len(n)] : object of type 'closure' is not subsettable
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