ox: Short hand if-else
In gogonzo/ox: Shorthand if-Else

Description Usage Arguments Details Value Examples

View source: R/ox.R

Short hand if-else functions for simple values switching.

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ox(.f, ..., .then = list(...)[[1]], .else = rev(list(...))[[1]])

xo(.f, ..., .then = list(...)[[1]], .else = rev(list(...))[[1]])

`.f`	(`function`) to be applied on `...`. Must return single logical value.
`...`	arguments passed to the `.f`.
`.then`	A positive-replacement. NOTE, that if `.then` is not specified directly by named argument then the first argument from `...` will be taken.
`.else`	A negative-replacement. NOTE, that if `.else` is not specified directly by named argument then the last argument from `...` will be considered as a replacement.

Figure: uml1.jpg

ox evaluates function .f which returns a single logical value and depending on the result ox returns:

on TRUE returns .then.
on FALSE returns .else.

It's important to note is that .then and .else have a default values set as the first and the last element of the .... This means that they don't have to be specified if both are arguments of .f.
If any of them are not arguments of .f then this argument should be specified directly as .then or .else, otherwise it will be passed to the function.

As, far as .then and .else won't be specified order of arguments in ... matters for ox but it's up to you if they are passed in the correct order to the .f. Then one, might consider name the argument so .f will be executed as expected. Consider following example

1 2	greater_than_by <- function(x, y, by) x > (y + by) ox(greater_than_by, x = 5, by = 3, y = 3)

In above, one needs to move y to the end so that it will be considered as .else.

To invert the switch one can use xo which is equivalent of ox(Negate(.f), ..., .then, .else).

object identical to .then or .else depending on the condition result.

# if (is.null(NULL)) NULL else 1
ox(NULL, .f = is.null, .else = 1)

# if (is("text", "character")) "text" else "not a character"
ox("text", .f = is, "character", .else = "not a character")

# if (1 > 2) 1 else 2
ox(`>`, 1, 2)
# if (!is.null(NULL)) NULL else 1
xo(NULL, .f = is.null, .else = 1)

# if (!is("text", "character")) "text" else "not a character"
xo("text", .f = is, "character", .else = "not a character")

# if (!1 > 2) 1 else 2
xo(`>`, 1, 2)