rlang: dots_values – R documentation

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dots_values

Evaluate dots with preliminary splicing

Description

This is a tool for advanced users. It captures dots, processes unquoting and splicing operators, and evaluates them. Unlike dots_list(), it does not flatten spliced objects, instead they are attributed a spliced class (see splice()). You can process spliced objects manually, perhaps with a custom predicate (see flatten_if()).

Usage

dots_values(
  ...,
  .ignore_empty = c("trailing", "none", "all"),
  .preserve_empty = FALSE,
  .homonyms = c("keep", "first", "last", "error"),
  .check_assign = FALSE
)

Arguments

`...`	Arguments to evaluate and process splicing operators.
`.ignore_empty`	Whether to ignore empty arguments. Can be one of `"trailing"`, `"none"`, `"all"`. If `"trailing"`, only the last argument is ignored if it is empty.
`.preserve_empty`	Whether to preserve the empty arguments that were not ignored. If `TRUE`, empty arguments are stored with `missing_arg()` values. If `FALSE` (the default) an error is thrown when an empty argument is detected.
`.homonyms`	How to treat arguments with the same name. The default, `"keep"`, preserves these arguments. Set `.homonyms` to `"first"` to only keep the first occurrences, to `"last"` to keep the last occurrences, and to `"error"` to raise an informative error and indicate what arguments have duplicated names.
`.check_assign`	Whether to check for `<-` calls passed in dots. When `TRUE` and a `<-` call is detected, a warning is issued to advise users to use `=` if they meant to match a function parameter, or wrap the `<-` call in braces otherwise. This ensures assignments are explicit.

Examples

dots <- dots_values(!!! list(1, 2), 3)
dots

# Flatten the objects marked as spliced:
flatten_if(dots, is_spliced)

rlang

Functions for Base Types and Core R and 'Tidyverse' Features

v0.4.11

MIT + file LICENSE

Authors

Lionel Henry [aut, cre], Hadley Wickham [aut], mikefc [cph] (Hash implementation based on Mike's xxhashlite), Yann Collet [cph] (Author of the embedded xxHash library), RStudio [cph]

Initial release