Damian Conway <[EMAIL PROTECTED]> wrote:
>
> There are in fact *two* types associated with any Perl variable:
>
> 1. Its "storage type" (i.e. the type(s) of value it can hold)
> This is specified before the variable or after an C<of> or C<returns>.
> It defaults to Scalar.
>
> 2. Its "implementation type" (i.e. the class that tells it how to act)
> This is specified after an C<is>. It defaults to the type indicated
> by the variable's sigil.
How does it work regarding inheritance and polymorphism ?
E.g. consider
my @a is Set of Apple;
my @b is Basket of Fruit;
with Apple isa Fruit, and Basket is a Set.
I assume I can use @a or @b where the expected type is:
@a @b
Set ok ok
Set of Fruit ok ok
Set of Apple ok no(?)
Basket no ok
Basket of Fruit no ok
Basket of Apple no no(?)
the errors being compile-time or run-time, depends on how much verification the
compiler can perform with its input. Reminds me the "Set<Apple>" C++ templates.
And the whole mess that comes with it (when you've got a statically typed language.)
