cnd: Create a condition object

In hadley/rlang: Functions for Base Types and Core R and 'Tidyverse' Features

Create a condition object

Description

These constructors create subclassed conditions, the objects that power the error, warning, and message system in R.

• cnd() creates bare conditions that only inherit from condition.

• Conditions created with error_cnd(), warning_cnd(), and message_cnd() inherit from "error", "warning", or "message".

• error_cnd() creates subclassed errors. See "rlang_error".

Use cnd_signal() to emit the relevant signal for a particular condition class.

Usage

cnd(class, ..., message = "", call = NULL, use_cli_format = NULL)

error_cnd(
  class = NULL,
  ...,
  message = "",
  call = NULL,
  trace = NULL,
  parent = NULL,
  use_cli_format = NULL
)

warning_cnd(
  class = NULL,
  ...,
  message = "",
  call = NULL,
  use_cli_format = NULL
)

message_cnd(
  class = NULL,
  ...,
  message = "",
  call = NULL,
  use_cli_format = NULL
)

Arguments

class	The condition subclass.
...	<dynamic> Named data fields stored inside the condition object.
message	A default message to inform the user about the condition when it is signalled.
call	A function call to be included in the error message. If an execution environment of a running function, the corresponding function call is retrieved.
use_cli_format	Whether to use the cli package to format message. See local_use_cli().
trace	A trace object created by trace_back().
parent	A parent condition object.

See Also

cnd_signal(), try_fetch().

Examples

# Create a condition inheriting only from the S3 class "foo":
cnd <- cnd("foo")

# Signal the condition to potential handlers. Since this is a bare
# condition the signal has no effect if no handlers are set up:
cnd_signal(cnd)

# When a relevant handler is set up, the signal transfers control
# to the handler
with_handlers(cnd_signal(cnd), foo = function(c) "caught!")
tryCatch(cnd_signal(cnd), foo = function(c) "caught!")

hadley/rlang documentation built on Dec. 17, 2024, 3:26 a.m.