How can I write code that optionally uses a module if it exists?

Question

If I want to write code that optionally uses a module how can I do it? For example, if I want to write code that warns Dumping an object if Data::Dumper is available or otherwise just warns, how can I do that?

Answer 1

This is an effective idiom for loading an optional module,

use constant has_Module => defined eval { require Module };

This will require the module if available, and store the status in a constant.

You can use this like,

use constant has_DataDumper => defined eval { require Data::Dumper };

warn "got object";
if ( has_DataDumper ) {
  warn Data::Dumper::Dumper( $obj );
}