These constructors make it easy to create subclassed conditions.
Conditions are objects that power the error system in R. They can
also be used for passing messages to pre-established handlers. See
vignette("conditions") for more information on how to use
the condition system.
new_cnd(.type = NULL, ..., .msg = NULL) cnd_error(.type = NULL, ..., .msg = NULL) cnd_warning(.type = NULL, ..., .msg = NULL) cnd_message(.type = NULL, ..., .msg = NULL)
The condition subclass.
Named data fields stored inside the condition object. These dots are evaluated with explicit splicing.
A default message to inform the user about the condition when it is signalled.
new_cnd() creates objects inheriting from
# Create a condition inheriting from the s3 type "foo": cnd <- new_cnd("foo") # Signal the condition to potential handlers. This has no effect if no # handler is registered to deal with conditions of type "foo": cnd_signal(cnd)#> NULL# If a relevant handler is on the current evaluation stack, it will be # called by cnd_signal(): with_handlers(cnd_signal(cnd), foo = exiting(function(c) "caught!"))#>  "caught!"# Handlers can be thrown or executed inplace. See with_handlers() # documentation for more on this. # Note that merely signalling a condition inheriting of "error" is # not sufficient to stop a program: cnd_signal(cnd_error("my_error"))#> Error:# you need to use stop() to signal a critical condition that should # terminate the program if not handled: # stop(cnd_error("my_error"))