unreachable_code_linter {lintr} | R Documentation |
Block unreachable code and comments following return statements
Description
Code after e.g. a return()
or stop()
or in deterministically false conditional loops like if (FALSE)
can't be reached;
typically this is vestigial code left after refactoring or sandboxing code, which
is fine for exploration, but shouldn't ultimately be checked in. Comments
meant for posterity should be placed before the final return()
.
Usage
unreachable_code_linter(
allow_comment_regex = getOption("covr.exclude_end", "# nocov end")
)
Arguments
allow_comment_regex |
Character vector of regular expressions which identify
comments to exclude when finding unreachable terminal comments. By default, this
includes the default "skip region" end marker for |
Tags
best_practices, configurable, readability
See Also
linters for a complete list of linters available in lintr.
Examples
# will produce lints
code_lines <- "f <- function() {\n return(1 + 1)\n 2 + 2\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "if (FALSE) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "while (FALSE) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "f <- function() {\n return(1)\n # end skip\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
# okay
code_lines <- "f <- function() {\n return(1 + 1)\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "if (foo) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "while (foo) {\n 2 + 2\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter()
)
code_lines <- "f <- function() {\n return(1)\n # end skip\n}"
writeLines(code_lines)
lint(
text = code_lines,
linters = unreachable_code_linter(allow_comment_regex = "# end skip")
)