If you Use strict and warnings, which you always should, then you would see the error message "Can't use string ("1") as a HASH ref while "strict refs" in use".

In my $self = @_;, you're using the array @_ in scalar context, which returns the number of elements, 1. You want either my ($self) = @_; or my $self = shift; instead. The former causes the right-hand side to be evaluated in list context, returning the elements of the array, and for the latter, see shift.