can we override "if" in R?
In my case, I create a new type of matrices and override matrix operations in R for these matrices. My goal is to make the system as transparent as possible, which means my system should execute the existing R code without modification. The problem is that when data is in my own vectors or matrices, "if" or "while" can't access their values unless we explicitly convert them into R objects. But this means users need to modify the existing code. So I hope I can override "if", "while", etc to access data in my own vectors and matrices directly. Does this sound reasonable? Best, Da On Sat, Mar 4, 2017 at 3:22 PM, Michael Lawrence
<lawrence.michael at gene.com> wrote:
I'm curious as to precisely why someone would want to do this. On Sat, Mar 4, 2017 at 11:49 AM, Da Zheng <zhengda1936 at gmail.com> wrote:
I'm just curious. Why making "if" generic is even more dangerous? Best, Da On Sat, Mar 4, 2017 at 1:22 PM, G?bor Cs?rdi <csardi.gabor at gmail.com> wrote:
`!` 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 <zhengda1936 at 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, G?bor Cs?rdi <csardi.gabor at 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 <zhengda1936 at 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
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