if_not_else_linter: Block statements like if (!A) x else y

In r-lib/lintr: A 'Linter' for R Code

Block statements like if (!A) x else y

Description

if (!A) x else y is the same as if (A) y else x, but the latter is easier to reason about in the ⁠else⁠ case. The former requires double negation that can be avoided by switching the statement order.

Usage

if_not_else_linter(exceptions = c("is.null", "is.na", "missing"))

Arguments

exceptions

Character vector of calls to exclude from linting. By default, is.null(), is.na(), and missing() are excluded given the common idiom !is.na(x) as "x is present".

Details

This only applies in the simple ⁠if/else⁠ case. Statements like if (!A) x else if (B) y else z don't always have a simpler or more readable form.

It also applies to ifelse() and the package equivalents dplyr::if_else() and data.table::fifelse().

Tags

configurable, consistency, readability

See Also

linters for a complete list of linters available in lintr.

Examples

# will produce lints
lint(
  text = "if (!A) x else y",
  linters = if_not_else_linter()
)

lint(
  text = "if (!A) x else if (!B) y else z",
  linters = if_not_else_linter()
)

lint(
  text = "ifelse(!is_treatment, x, y)",
  linters = if_not_else_linter()
)

lint(
  text = "if (!is.null(x)) x else 2",
  linters = if_not_else_linter(exceptions = character())
)

# okay
lint(
  text = "if (A) x else y",
  linters = if_not_else_linter()
)

lint(
  text = "if (!A) x else if (B) z else y",
  linters = if_not_else_linter()
)

lint(
  text = "ifelse(is_treatment, y, x)",
  linters = if_not_else_linter()
)

lint(
  text = "if (!is.null(x)) x else 2",
  linters = if_not_else_linter()
)

r-lib/lintr documentation built on Dec. 20, 2024, 7:24 p.m.