lintr (version 3.1.0)

paste_linter: Raise lints for several common poor usages of paste()

Description

The following issues are linted by default by this linter (see arguments for which can be de-activated optionally):

Usage

paste_linter(allow_empty_sep = FALSE, allow_to_string = FALSE)

Arguments

allow_empty_sep

Logical, default FALSE. If TRUE, usage of paste() with sep = "" is not linted.

allow_to_string

Logical, default FALSE. If TRUE, usage of paste() and paste0() with collapse = ", " is not linted.

Tags

best_practices, configurable, consistency

Details

1. Block usage of paste() with sep = "". paste0() is a faster, more concise alternative.

2. Block usage of paste() or paste0() with collapse = ", ". toString() is a direct wrapper for this, and alternatives like glue::glue_collapse() might give better messages for humans.

3. Block usage of paste0() that supplies sep= -- this is not a formal argument to paste0, and is likely to be a mistake.

4. Block usage of paste() / paste0() combined with rep() that could be replaced by strrep(). strrep() can handle the task of building a block of repeated strings (e.g. often used to build "horizontal lines" for messages). This is both more readable and skips the (likely small) overhead of putting two strings into the global string cache when only one is needed.

   Only target scalar usages -- strrep can handle more complicated cases (e.g. strrep(letters, 26:1), but those aren't as easily translated from a paste(collapse=) call.

See Also

linters for a complete list of linters available in lintr.

Examples

# will produce lints
lint(
  text = 'paste("a", "b", sep = "")',
  linters = paste_linter()
)

lint(
  text = 'paste(c("a", "b"), collapse = ", ")',
  linters = paste_linter()
)

lint(
  text = 'paste0(c("a", "b"), sep = " ")',
  linters = paste_linter()
)

lint(
  text = 'paste0(rep("*", 10L), collapse = "")',
  linters = paste_linter()
)

# okay
lint(
  text = 'paste0("a", "b")',
  linters = paste_linter()
)

lint(
  text = 'paste("a", "b", sep = "")',
  linters = paste_linter(allow_empty_sep = TRUE)
)

lint(
  text = 'toString(c("a", "b"))',
  linters = paste_linter()
)

lint(
  text = 'paste(c("a", "b"), collapse = ", ")',
  linters = paste_linter(allow_to_string = TRUE)
)

lint(
  text = 'paste(c("a", "b"))',
  linters = paste_linter()
)

lint(
  text = 'strrep("*", 10L)',
  linters = paste_linter()
)