[R] calling "exists" function inside another function is not working

[David Winsemius]

On May 14, 2011, at 3:30 AM, utkarshsinghal wrote:

>
>   Hi all,
>   I want to define a function such that one of its argument if  
> passed do one
>   thing and if not passed do the second thing.

?missing

> So basically, I have to check
>   whether the argument is passed or not inside the function. I am  
> trying to
>   use 'exists' function to do this.
>> f = function(a,b){exists("b")}
>> f(a=3, b=4)
>   [1] TRUE
>   This is working as expected.
>   But if I do the following:
>> f(a=3)
>   [1] TRUE
>   Can anybody explain why this function is returning TRUE here.
> -- 
> Many thanks,
> Utkarsh
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David Winsemius, MD
West Hartford, CT