R: Make a promise explicit by converting into a formula.

f_capture {lazyeval} | R Documentation

## Make a promise explicit by converting into a formula.

### Description

This should be used sparingly if you want to implement true non-standard evaluation with 100% magic. I recommend avoiding this unless you have strong reasons otherwise since requiring arguments to be formulas only adds one extra character to the inputs, and otherwise makes life much much simpler.

### Usage

    f_capture(x)

    dots_capture(..., .ignore_empty = TRUE)

### Arguments

`x, ...` | An unevaluated promises
`.ignore_empty` | If `TRUE`, empty arguments will be silently dropped.

### Value

`f_capture` returns a formula; `dots_capture` returns a list of formulas.

### Examples

    f_capture(a + b)
    dots_capture(a + b, c + d, e + f)

    # These functions will follow a chain of promises back to the
    # original definition
    f <- function(x) g(x)
    g <- function(y) h(y)
    h <- function(z) f_capture(z)
    f(a + b + c)

[Package lazyeval version 0.2.1 Index]