Let's say I have a subroutine defined as
sub foo (ARRAY $arr) { ... }
And, I have a class Bar. Today, it is defined as
package Bar;
sub new { bless [], shift }
This means that
my $bar = Bar->new;
foo( $bar );
will work just fine. But, what happens if the implementation of Bar changes from arrayref to hashref? This is a completely internal change, but one that will break the code listed above.
Personally, I would define it to be
if ($signature)
{
if (blessed $x)
{
return TRUE if $x->isa( $signature );
}
elsif (ref $x)
{
return TRUE if ref $x eq $signature;
}
else
{
die "$x doesn't match $signature\n";
}
}
In other words, if it's been blessed, you only consider the class - not the underlying implementation.
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