Style guide

Instance variables and getters / setters

We use instance vars only:

in the constructor
for memoization

For everything else we use proper getters / setters.

If possible those should be private.

Data types

Class or module names that are carried around in hashes and configuration and what not should be designated by constants. So DuplicateMethodCall, not :DuplicateMethodCall or "DuplicateMethodCall"
Hash keys should be all symbols unless they designate classes / modules - see above.
Everything else like messages or parameters in smell warnings should be strings, nothing else.