Returns TRUE
for any R object that can be used as a Filter
for Loggers or, Appenders:
a function
with the single argument event
;
an EventFilter R6::R6 object; or
any object with a $filter(event)
method.
Note: A Filter must return a scalar TRUE
or FALSE
, but this
property cannot be checked by is_filter()
.
is_filter(x)
any R Object
TRUE
or FALSE