`!` is a generic, `if` is not. You can define an `if` that is generic, but this might be even more dangerous....
❯ `if` <- function(a, b, c) UseMethod("if") ❯ `if.default` <- function(a,b,c) base::`if`(a, b, c) ❯ `if.foo` <- function(a, b, c) FALSE ❯ a <- structure(42, class = "foo") ❯ if (a) TRUE else FALSE [1] FALSE ❯ if (1) TRUE else FALSE [1] TRUE Gabor On Sat, Mar 4, 2017 at 5:47 PM, Da Zheng <zhengda1...@gmail.com> wrote: > Thanks. > Can I override it for a specific class? > I can do that for operators such as "!". For example, "!.fm" works for > objects of the class "fm". > It seems I can't do the same for "if". > > Best, > Da > > On Sat, Mar 4, 2017 at 12:41 PM, Gábor Csárdi <csardi.ga...@gmail.com> wrote: >> You can. Perhaps needless to say, be careful with this. >> >> ❯ `if` <- function(...) FALSE >> ❯ if (TRUE) TRUE else FALSE >> [1] FALSE >> >> G. >> >> On Sat, Mar 4, 2017 at 5:36 PM, Da Zheng <zhengda1...@gmail.com> wrote: >>> Hello, >>> >>> I heard we can override almost everything in R. Is it possible to >>> override "if" keyword in R to evaluate my own object instead of a >>> logical value? >>> >>> Thanks, >>> Da >>> >>> ______________________________________________ >>> R-devel@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel