May 26, 2018

Call isa, can, does and DOES safely on things that may not be objects

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.

e.g. my $isa_Foo = $maybe_an_object->$_call_if_objectisa => ‘Foo’;

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 ModuleRuntime is a good way to check for something you might be able to call methods on if you want to do that.

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