[Rd] Unexpected argument-matching when some are missing

[Emil Bode]

But the main point is where arguments are mixed together:

> debugonce(plot.default)
> plot(x=1:10, y=, 'l')
...
Browse[2]> missing(y)
[1] FALSE
Browse[2]> y
[1] "l"
Browse[2]> type
[1] "p"

I think that's what I fall over mostly: that named, empty arguments behave entirely different from omitting them (", ,")

And I definitely agree we need a guru to explain it all to us (

Cheers, Emil Bode


On 30/11/2018, 15:35, "S Ellison" <S.Ellison using LGCGroup.com> wrote:

    > Yes, I think all of that is correct. But y _is_ missing in this sense:
    > > plot(1:10, y=)
    > > ...
    > Browse[2]> missing(y)
    
    Although I said what I meant by 'missing' vs 'not present', it wasn't exactly what missing() means. My bad.
    missing() returns TRUE if an argument is not specified in the call _whether or not_ it has a default, hence the behaviour of missing(y) in debug(plot).
    
    But we can easily find out whether a default has been assigned:
    plot(1:10, y=, type=)
    Browse[2]> y
    NULL
    Browse[2]> type
    "p"
    
    ... which is consistent with silent omission of 'y=' and 'type=' 
    
    
    Still waiting for a guru...
    
    Steve E
    
    
    
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