I have some easy code which behaves a bit strangely (to my humble understanding). It is a reduced version of what I am actually running, to eliminate possible interference with other parts of the code and not take up even more space here: 
use Data::Dumper;

my $N = Value->new(23);

warn Dumper($N * 2);
warn Dumper($N*= 2);

my $test;
$test->{obj} = $N;

warn Dumper($N * 2);
warn Dumper($N*= 2);

package Value;

use overload ('*=' => 'mulSet');
use overload ('*' => 'mul');

sub new {
    my ($class, $value) = (shift, @_);
    $class = ref($class) || $class;
    my $self = {value => $value};
    return bless $self, $class;
}

sub mul {
    my ($self, $num) = @_;
    return $self->new($self->{value} * $num);
}

sub mulSet {
    my ($self, $num) = @_;
    $self->{value}*= $num;
    return $self;    
}

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This produces the following output: 
$VAR1 = bless( {
                 'value' => 46
               }, 'Value' );
$VAR1 = bless( {
                 'value' => 46
               }, 'Value' );
$VAR1 = bless( {
                 'value' => 92
               }, 'Value' );
Operation "=": no method found, argument in overloaded package Value
at /bla/bla/bla/test/Value.pl line 12.

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However, if I comment out either one of the following lines 
$test->{obj} = $N;
use overload ('*=' => 'mulSet');

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or the
return $self; in mulSet, the error message does not happen. The commenting out of return $self so far is a feasible workaround to my problem, but I would like to be able to use it at some point later on and also like to know why it works, while the others produce errors, (especially what the $test->{obj} = $N; does that is so bad) , so I don't run in similar problems in the future. Workarounds never are very satisfying...

In reply to overload conflict between * and *= (as an example) by yogibimbi

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