T M
class X::Does::TypeObject
Error ReportCollection examples

Error due to mixing into a type object

class X::Does::TypeObject is Exception {}

When you try to add one or more roles to a type object with does after it has been composed, an error of type X::Does::TypeObject is thrown:

Mu does Numeric;    # Cannot use 'does' operator with a type object. 

The correct way to apply roles to a type is at declaration time:

class GrassmannNumber does Numeric { ... };
role AlgebraDebugger does IO { ... };
grammar IntegralParser does AlgebraParser { ... };

Roles may only be runtime-mixed into defined object instances:

GrassmannNumber.new does AlgebraDebugger;

(This restriction may be worked around by using augment or supersede, or with dark Metamodel magics, but this will likely result in a significant performance penalty.)

Methods

method type

method type(X::Does::TypeObject:D: --> Mu:U)

Returns the type object into which the code tried to mix in a role.