This might be completely off the mark, but why are you putting constants in a module instead of a configuration file?

If it's to "hide" login information so that it's not in a script where people may be able to see it, that may not be a good idea since anyone who can access the module in a script with a 'use' call can access that information.

In some cases it makes more sense to put that information in a separate configuration file that you can restrict access to certain processes.

Other advantages of using a configuration file as opposed to a module:

• A sysadmin can change a configuration file without touching code and accidentally causing an error.
• The same code can be used for multiple databases by changing a reference to the configuration file rather than creating another module.