dots: Set an advanced argument

In lcolladotor/dots: Simplifying function calls

Description

From the ... argument used in your function, find if a specific argument was included and extract its value.

Usage

dots(name, value, ...)

Arguments

name	Name of the advanced argument to look for in ...
value	The default value of the advanged argument. If this advanced argument is used in several of your functions, we recommend using getOption('value') and explaining this option in your package vignette geared towards experienced users.
...	Advanced arguments. See dotsMethods.

Details

Note that you can make dots() even more powerful by using getOption to define value. This is particularly useful if you use the same advanced argument in several functions.

Author(s)

L. Collado-Torres

See Also

dotsMethods

Examples

## Simple example that calculates the max between 'x' and 'y' with a
## specified minimum value to return.

minMax <- function(x, y, ...) {
    minValue <- dots('minValue', 0, ...)
    res <- max(x, y, minValue)
    return(res)
}
minMax(1:2, 3:4)
minMax(1:2, 3:4, minValue = 5)

## See the function 'last' included in this package.
## It's an example where most users don't need the 'selector' argument
## but the experienced users can find it and use it.
last
## Examples using this function
l <- list(a = 1:10, b = 11:20)
last(l)
last(l, selector = '[[')


## A more complicated example is 'recursive_last' where we specifically
## define the 'selector' argument that is the then passed to 'last'
recursive_last

## Example usages of 'recursive_last'
l2 <- list(j = 21:30, k = list(a = 1:10, b = 11:20))
recursive_last(l2)
recursive_last(l2, level = 2L, selector = '[[')
recursive_last(l2, level = 3L, selector = '[[')
recursive_last(l2, level = 2L, selector = c('[', '[['))

## Arguably these examples are simple, but the idea is that dots()
## can simplify very long function calls where some parameters will be used
## by a minority of the users.

lcolladotor/dots documentation built on Aug. 24, 2019, 5:23 p.m.