qq_show: Show injected expression

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Show injected expression

Description

qq_show() helps examining injected expressions inside a function. This is useful for learning about injection and for debugging injection code.

Arguments

expr	An expression involving injection operators.

Examples

qq_show() shows the intermediary expression before it is evaluated by R:

list2(!!!1:3)
#> [[1]]
#> [1] 1
#> 
#> [[2]]
#> [1] 2
#> 
#> [[3]]
#> [1] 3

qq_show(list2(!!!1:3))
#> list2(1L, 2L, 3L)

It is especially useful inside functions to reveal what an injected expression looks like:

my_mean <- function(data, var) {
  qq_show(data %>% dplyr::summarise(mean({{ var }})))
}

mtcars %>% my_mean(cyl)
#> data %>% dplyr::summarise(mean(^cyl))

See Also

• Injecting with !!, !!!, and glue syntax

hadley/rlang documentation built on Nov. 1, 2024, 4 p.m.