Can you set a global variable to change the set of variable you use?

I'm working in a multi environment layout with same and different versions of the same product to test. Is there a pattern or way to set a single global variable to, say, switch which files the file variables for logins point to?

For example:
Environment 1 called TEST
Environment 2 called PRE

TEST uses a different set of logins and passwords than PRE.

Just to be clear, I have multiple roles with logins for each environment so I have some 5+ different login file variables and I don't want to forget to switch one before I do a shakedown or something