cnd-signal.md
In rlang: Functions for Base Types and Core R and 'Tidyverse' Features

cnd_signal() creates a backtrace if needed

Code
  print(err)
Output
  <error/rlang_error_foobar>
  ---
  Backtrace:
       x
    1. +-rlang::catch_cnd(f())
    2. | +-rlang::eval_bare(...)
    3. | +-base::tryCatch(...)
    4. | | \-base (local) tryCatchList(expr, classes, parentenv, handlers)
    5. | |   \-base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
    6. | |     \-base (local) doTryCatch(return(expr), name, parentenv, handler)
    7. | \-base::force(expr)
    8. \-rlang (local) f()
    9.   \-rlang (local) g()
   10.     \-rlang (local) h()

`inform()` and `warn()` with recurrent footer handle newlines correctly

Code
  inform("foo", .frequency = "regularly", .frequency_id = as.character(runif(1)))
Message
  foo
  This message is displayed once every 8 hours.
Code
  inform("bar", .frequency = "regularly", .frequency_id = as.character(runif(1)))
Message
  bar
  This message is displayed once every 8 hours.
Code
  warn("foo", .frequency = "regularly", .frequency_id = as.character(runif(1)))
Condition
  Warning:
  foo
  This warning is displayed once every 8 hours.
Code
  warn("bar", .frequency = "regularly", .frequency_id = as.character(runif(1)))
Condition
  Warning:
  bar
  This warning is displayed once every 8 hours.

`frequency` has good error messages

Code
  (expect_error(inform("foo", .frequency = "once", .frequency_id = NULL)))
Output
  <error/rlang_error>
  Error in `inform()`:
  ! `.frequency_id` must be supplied with `.frequency`.
Code
  (expect_error(warn("foo", .frequency = "once", .frequency_id = 1L)))
Output
  <error/rlang_error>
  Error in `warn()`:
  ! `.frequency` must be a valid name, not the number 1.

signal functions check inputs

Code
  (expect_error(abort(error_cnd("foo"))))
Output
  <error/rlang_error>
  Error in `abort()`:
  ! `message` must be a character vector, not a <foo> object.
Code
  (expect_error(inform(error_cnd("foo"))))
Output
  <error/rlang_error>
  Error in `inform()`:
  ! `message` must be a character vector, not a <foo> object.
Code
  (expect_error(warn(class = error_cnd("foo"))))
Output
  <error/rlang_error>
  Error in `warn()`:
  ! `class` must be a character vector, not a <foo> object.
Code
  (expect_error(abort("foo", call = base::call)))
Output
  <error/rlang_error>
  Error in `abort()`:
  ! `call` must be a call or environment, not a primitive function.

error_cnd() still accepts `.subclass`

Code
  expect_equal(error_cnd(.subclass = "foo"), error_cnd("foo"))
Condition
  Warning:
  The `.subclass` argument of `error_cnd()` has been renamed to `class`.
Code
  expect_error(abort("foo", .subclass = "bar"), class = "bar")
Condition
  Warning:
  The `.subclass` argument of `abort()` has been renamed to `class`.