$buffer = 'x' x 10000000;
# memory used 12,200kb

*x = \$buffer;
# mem used 12.200kb

print length $x;
10000000

print substr $x, 0, 30;
xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

##</code><code>##

sub test : lvalue { $buffer };

print length test;
10000000

print substr test, 0, 10;
xxxxxxxxxx

substr( test, 3, 3 ) = 'ABC';

print substr test, 0, 10;
xxxABCxxxx

print length test;
10000000


##</code><code>##

 
print substr obj->test, 20_000, 5;
substr( obj->test, 20_000, 5 ) = 'hello';