Encourage usage of the null coalescing operator %||%

The x %||% y is equivalent to if (is.null(x)) y else x, but more expressive. It is exported by R since 4.4.0, and equivalents have been available in other tidyverse packages for much longer, e.g. 2008 for ggplot2.

Usage

coalesce_linter()

See also

linters for a complete list of linters available in lintr.

Tags

best_practices, consistency, readability

Examples

# will produce lints
lint(
  text = "if (is.null(x)) y else x",
  linters = coalesce_linter()
)
#> <text>:1:1: warning: [coalesce_linter] Use x %||% y instead of if (is.null(x)) y else x.
#> if (is.null(x)) y else x
#> ^~~~~~~~~~~~~~~~~~~~~~~~

lint(
  text = "if (!is.null(x)) x else y",
  linters = coalesce_linter()
)
#> <text>:1:1: warning: [coalesce_linter] Use x %||% y instead of if (!is.null(x)) x else y.
#> if (!is.null(x)) x else y
#> ^~~~~~~~~~~~~~~~~~~~~~~~~

lint(
  text = "if (is.null(x[1])) x[2] else x[1]",
  linters = coalesce_linter()
)
#> <text>:1:1: warning: [coalesce_linter] Use x %||% y instead of if (is.null(x)) y else x.
#> if (is.null(x[1])) x[2] else x[1]
#> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# okay
lint(
  text = "x %||% y",
  linters = coalesce_linter()
)
#> ℹ No lints found.

lint(
  text = "x %||% y",
  linters = coalesce_linter()
)
#> ℹ No lints found.

lint(
  text = "x[1] %||% x[2]",
  linters = coalesce_linter()
)
#> ℹ No lints found.