trait is required (Attribute)
Documentation for trait
is required (Attribute) assembled from the following types:
is required will mark the attribute as to be filled with a value when the object is instantiated. Failing to do so will result in a runtime error.
my = C.new;CATCH# OUTPUT: «X::Attribute::Required: The attribute '$!a' is required, but you did not provide a value for it.␤»