I don't follow you on the advantage or reason for only using the closed-over variable in one place, that being a function that returns it.
It is largely about scope management and making sure you control how many refs a given object might have. Here is some example (NOTE: I have not run this to confirm it works exactly as expected, but you should get the idea of you are familar with MooseX::Role::Parameterized)
package My::Parameterized::Role;
use MooseX::Role::Parameterized;
parameter 'something' => ( isa => 'Str' );
role {
my $p = shift;
{
my $something = $p->param('something');
method 'static_something' => sub {
return $something;
};
}
}
So, first let me say that this is likely overkill, but having had some nasty ref-counting leaks in the past I have learned to be cautious. So as you can see here, the 'static_something' method I am creating only closes over the
$something variable, which we know is a string. If I had written 'static_something' like so:
method 'static_something' => sub {
return $p->param('something');
};
Then the method would close over the
$p object, which *might* become a source of leaks.
Like I said, probably overkill, but I prefer to be cautious in this kind of environment.