Daniel Ruoso wrote:
> Jon Lang wrote:
>> Note that this ought only be true of class inheritance; with role
>> composition, there should only be one $!bar in the class, no matter
>> how many roles define it.
> er... what does that mean exactly?

Unless something has drastically changed since I last checked the
docs, roles tend to be even more ethereal than classes are.  You can
think of a class as being the engine that runs objects; a role, OTOH,
should be thought of as a blueprint that is used to construct a class.
 Taking your example:

>   role B {
>       has $!a;
>   }
>   role C {
>       has $!a;
>   }
>   class A does B, C {
>       method foo() {
>          say $!a;
>       }
>   }
> I think in this case $!B::a and $!C::a won't ever be visible, while the
> reference to $!a in class A will be a compile time error.


> Or does that mean that
>    class A does B, C {...}
> actually makes the declarations in B and C as if it were declared in the
> class A?

Correct.  Declarations in roles are _always_ treated as if they were
declared in the class into which they're composed.  And since only
classes are used to instantiate objects, the only time that a role
actually gets used is when it is composed into a class.

Jonathan "Dataweaver" Lang

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