require EXPR only accepts Class/Name.pm style module names, not Class::Name. How frustrating! For that, we provide load_class 'Class::Name'. It's often useful to test whether a module can be loaded, instead of throwing an error when it's not available. For that, we provide try_load_class 'Class::Name'. Finally, sometimes we need to know whether a particular class has been loaded. Asking %INC is an option, but that will miss inner packages and any class for which the filename does not correspond to the package name. For that, we provide is_class_loaded 'Class::Name'. WWW: https://metacpan.org/pod/Class::Load