perl-Safe-Isa

How many times have you found yourself writing:
if ($obj->isa('Something')) {
and then shortly afterwards cursing and changing it to:
if (Scalar::Util::blessed($obj) and $obj->isa('Something')) {
Right. That's why this module exists.
Since perl allows us to provide a subroutine reference or a method name to
the -> operator when used as a method call, and a subroutine doesn't
require the invocant to actually be an object, we can create safe versions
of isa, can and friends by using a subroutine reference that only tries to
call the method if it's used on an object. So:
my $isa_Foo = $maybe_an_object->$_call_if_object(isa => 'Foo');
is equivalent to
my $isa_Foo = do {
    if (Scalar::Util::blessed($maybe_an_object)) {
      $maybe_an_object->isa('Foo');
    } else {
      undef;
    }
  };
Note that we don't handle trying class names, because many things are valid
class names that you might not want to treat as one (like say "Matt") - the
'is_module_name' function from Module::Runtime is a good way to check for
something you might be able to call methods on if you want to do that.
We are careful to make sure that scalar/list context is preserved for the
method that is eventually called.

          

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License: Artistic-1.0 OR GPL-1.0-or-later
URL: http://search.cpan.org/dist/Safe-Isa/