Another way to think about it might be: why do you have to check that ShopperDueDate is true in the first place?

For example, you could have $shop->ShopperDueDate throw an exception if it's not true that it can('day_name'), then

eval { say $shop->ShopperDueDate->day_name };
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Ok, I'm joking, but what about never allowing ->ShopperDueDate to be a non-DateTime object (or whatever). Like in Moose:

package Shop;
use Moose;
....
has 'ShopperDueDate' => (...., isa => 'DateTime', default => sub { Dat
+eTime->new });
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Now when $shop is initialized, you know that ShopperDueDate can call day_name, so you just write

say $shop->ShopperDueDate->day_name;
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