PackageName::subname() is not how you call a method. That's how you call a normal subroutine in package PackageName.

Anyway...

# call a method by name.
# this works for real methods only.
my $method = "some_method";

ClassName->$method(@arguments);
$object->$method(@arguments);

# or ....

# get a subroutine reference and call that
# this works provided you call it the right way
my $subref = Package->can("some_method");

# call subref as class method
Package->$subref(@args);

# call subref as object method
$object->$subref(@args);

# call subref as normal subroutine
$subref->(@args);
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The last construct is probably what you need.