cnd_message() assembles an error message from three generics:
cnd_header()
cnd_body()
cnd_footer()
Methods for these generics must return a character vector. The
elements are combined into a single string with a newline
separator. Bullets syntax is supported, either through rlang (see
format_error_bullets()), or through cli if the condition has
use_cli_format set to TRUE.
The default method for the error header returns the message field
of the condition object. The default methods for the body and
footer return the the body and footer fields if any, or empty
character vectors otherwise.
cnd_message() is automatically called by the conditionMessage()
for rlang errors, warnings, and messages. Error classes created
with abort() only need to implement header, body or footer
methods. This provides a lot of flexibility for hierarchies of
error classes, for instance you could inherit the body of an error
message from a parent class while overriding the header and footer.
cnd_message(cnd, ..., inherit = TRUE, prefix = FALSE)
cnd_header(cnd, ...)
cnd_body(cnd, ...)
cnd_footer(cnd, ...)A condition object.
Arguments passed to methods.
Wether to include parent messages. Parent messages
are printed with a "Caused by error:" prefix, even if prefix is
FALSE.
Whether to print the full message, including the
condition prefix (Error:, Warning:, Message:, or
Condition:). The prefix mentions the call field if present,
and the srcref info if present. If cnd has a parent field
(i.e. the condition is chained), the parent messages are included
in the message with a Caused by prefix.