On Fri, Dec 3, 2021 at 3:14 AM Bert Gunter wrote:
>
> Those are both helpful comments. Would it not be useful to say
> something along these lines in ?class. ?
> The key point I missed is that there often(but not always) must be an
> *explicit* class **attribute** for method dispatch; and class()
Those are both helpful comments. Would it not be useful to say
something along these lines in ?class. ?
The key point I missed is that there often(but not always) must be an
*explicit* class **attribute** for method dispatch; and class() does
not indicate whether its value is explicit or not (just
The reason for this behaviour is that finding methods is a lot slower
than just evaluating the built-in function. So R takes the time to
determine if there's an attribute named "class" attached, but doesn't go
searching further if there isn't one.
Duncan Murdoch
On 02/12/2021 3:10 p.m., Andr
class() does not always return the class attribute, try something more like
attr(, "class"), you'll see what I mean
On Thu, Dec 2, 2021, 15:23 Bert Gunter wrote:
> "This is because + dispatches on the class attribute, which a string
> like "test" has set to NULL"
> Not true.
>
> > class('test')
"This is because + dispatches on the class attribute, which a string
like "test" has set to NULL"
Not true.
> class('test')
[1] "character"
But apparently, as Denes and Jeff said, the class must be explicitly
set, rather than relying on its built-in/implicit type.
With the above hint, I looked u
This is because + dispatches on the class attribute, which a string like
"test" has set to NULL, so it doesn't dispatch. You can add the class
yourself like structure("test", class = "character") and that should work.
I'm not sure where it's explained, but most primitive functions dispatch on
the
I think the fact that character is a built-in type rather than an S3 class has
something to do with it.
On December 2, 2021 11:31:47 AM PST, Bert Gunter wrote:
>... and probably a dumb one and almost certainly not of interest to
>most R users. But anyway...
>
>?"+" says:
>"The unary and binary a
... and probably a dumb one and almost certainly not of interest to
most R users. But anyway...
?"+" says:
"The unary and binary arithmetic operators are generic functions:
methods can be written for them individually or via the Ops group
generic function. "
So:
"+.character" <- function(e1, e2)
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