The UNIVERSAL 'can' method should tell you this. From perlobj:

     Sometimes you want to call a method when you don't know the
     method name ahead of time.  You can use the arrow form,
     replacing the method name with a simple scalar variable
     containing the method name or a reference to the function.

         $method = $fast ? "findfirst" : "findbest";
         $fred->$method(@args);          # call by name

         if ($coderef = $fred->can($parent . "::findbest")) {
             $self->$coderef(@args);     # call by coderef
         }
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Basically:

$obj->method(1, 2, 3);         # general case

if ($obj->can('method')) {
    print "Yep, \$obj has a method named 'method'\n";
}

if ($sub = $obj->can('method')) {
    $sub->($obj, 1, 2, 3);     # same effect as general case
}
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