Block usage of pipes nested inside other calls

Nesting pipes harms readability; extract sub-steps to separate variables, append further pipeline steps, or otherwise refactor such usage away.

Usage

nested_pipe_linter(
  allow_inline = TRUE,
  allow_outer_calls = c("try", "tryCatch", "withCallingHandlers")
)

Arguments

allow_inline

Logical, default TRUE, in which case only "inner" pipelines which span more than one line are linted. If FALSE, even "inner" pipelines that fit in one line are linted.

allow_outer_calls

Character vector dictating which "outer" calls to exempt from the requirement to unnest (see examples). Defaults to try(), tryCatch(), and withCallingHandlers().

See also

linters for a complete list of linters available in lintr.

Tags

configurable, consistency, readability

Examples

# will produce lints
code <- "df1 %>%\n  inner_join(df2 %>%\n    select(a, b)\n  )"
writeLines(code)
#> df1 %>%
#>   inner_join(df2 %>%
#>     select(a, b)
#>   )
lint(
  text = code,
  linters = nested_pipe_linter()
)
#> <text>:2:14: warning: [nested_pipe_linter] Don't nest pipes inside other calls.
#>   inner_join(df2 %>%
#>              ^~~~~~~

lint(
  text = "df1 %>% inner_join(df2 %>% select(a, b))",
  linters = nested_pipe_linter(allow_inline = FALSE)
)
#> <text>:1:20: warning: [nested_pipe_linter] Don't nest pipes inside other calls.
#> df1 %>% inner_join(df2 %>% select(a, b))
#>                    ^~~~~~~~~~~~~~~~~~~~

lint(
  text = "tryCatch(x %>% filter(grp == 'a'), error = identity)",
  linters = nested_pipe_linter(allow_outer_calls = character())
)
#> ℹ No lints found.

# okay
lint(
  text = "df1 %>% inner_join(df2 %>% select(a, b))",
  linters = nested_pipe_linter()
)
#> ℹ No lints found.

code <- "df1 %>%\n  inner_join(df2 %>%\n    select(a, b)\n  )"
writeLines(code)
#> df1 %>%
#>   inner_join(df2 %>%
#>     select(a, b)
#>   )
lint(
  text = code,
  linters = nested_pipe_linter(allow_outer_calls = "inner_join")
)
#> ℹ No lints found.

lint(
  text = "tryCatch(x %>% filter(grp == 'a'), error = identity)",
  linters = nested_pipe_linter()
)
#> ℹ No lints found.