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rpolymorphismampersand

Overloading Ampersand & operator in R

I like to overload my ampersand operator with paste. So that way I can paste stuff easily. Like this:

R> "Hello" & " World"
 [1] "Hello World"

And the way I achieve this is:

"&" <- function(...){paste(..., sep = "")}

This is all fine and dandy but you lose the ability to use ampersand as a natural "and" operator. What would be the best, fastest most beautiful way to overload my ampersand so that it recognizes when the inputs are logical?

TRUE & FALSE == FALSE

etc.

Solution

  • You'll need to use the S3 object system in R:

    `&` <- function(e1, e2) UseMethod("&", c(e1, e2))
`&.default` <- function(e1, e2) paste(e1, e2)
`&.logical` <- function(e1, e2) .Primitive("&")(e1, e2)

    Now you can use & as you would expect:

    > 1 & 2
[1] "1 2"
> TRUE & FALSE
[1] FALSE
> "Hello" & "World"
[1] "Hello World"
>