The lines ...

my $objName = "foo";
my $testObj = new $objName();
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work. Here is the code I used to test.

#!/usr/bin/perl
use strict;
use warnings;

package Foo;
sub new {
    bless {}, shift;
}

package main;
my $objName = "Foo";
my $obj = $objName->new();
my $obj1 = new $objName();
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BTW, you can use eval to use modules at runtime and capture problems finding the module, e.g.

my $moduleName = "Foo";
eval "use $moduleName";
if ($@) { # could be problems with the loading of the module Foo
....
}
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