I have done what you said. Here is the code...
Simple class example for demonstration purposes:
#---Sample.pm---
package Sample;

use warnings;
use strict;

use overload( '+'    => \&add,
        fallback => 1, );

sub TIESCALAR
{
    my $class = shift;
    my $self = { data => [@_], };
    bless( $self, $class );
    return $self;    
}

sub add
{
    $_ .= $_[1] foreach( @{$_[0]->{data}} );
}

sub STORE
{
    @{$_[0]->{data}} = (ref( $_[1] ) eq 'ARRAY') ? @{$_[1]}: ($_[1]);
}

sub FETCH
{
    return $_[0];
}

1;
#---------------

[download]
Next is the program.. 
#----code.pl----
use warnings;
use strict;

use Sample;

my $var1;
my $var2 = tie( $var1, 'Sample', 'black', 'white' );

# The assigment test...
#$var1 = 'green';
#$var2 = ['green','red'];

# The overload test...
#$var1 + ' bishop';
#$var2 + ' bishop';

#print ref($var2),"\n";
print join( "\n", @{$var2->{data}} );

exit 0;
#---------------

[download]
Compiler warnings/errors: (addition operation on the tie() variable $var1)
Useless use of addition (+) in void context at code.pl line 28.
Argument " bishop" isn't numeric in addition (+) at code.pl line 28.

[download]
* The returned variable $var2 however, will cause the 1st warning but successfully calls the 'addition' Sample::add.

The opposite works with assignment:
$var2 = ['green','red'] destroys the class instance of Sample and becomes an array reference. $var1 = ['green','red'] works as it should because of tie()!

Both operations don't work on the same variable, $var1 can't do the addition + and $var2 can't do the assignment!

In reply to Re: Overloading assignment by v_o_i_d
in thread Overloading assignment by v_o_i_d

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