if you want to load a module whos name is calculated by you
and load it in a particular place in the program at the particular
time that code is executed yes you can use require
having in mind that the difference between require and use is that
use loads modules at compile-time and
require at run-time.



altough not very ethic,your code could have been written without either "use" or "require" of them
like this :

#!/usr/bin/perl 

sub new_pkg {
our $i;
$i++;
eval <<__SOMECODE__
package demo$i;

sub new {
    my \$class = shift;
    my \$self = {class => \$class};
    bless (\$self,\$class);
    return \$self;
}

sub test {
    print "demo$i\\n";
}

__SOMECODE__
;

};

new_pkg for 1..10;
for (1..10) {
    my $type_of_obj = "demo$_";
    my $new_obj=$type_of_obj->new;
    $new_obj->test;
};
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P.S. : beware,as this is not a best practice(just showing that you can do things this way too)