Raise error when (re)naming columns on migration with ActiveRecord instance method names.

Pratik,

Great suggestion, looks much better now, i believe my previous implementation was before instance_method_already_implemented? was in the core.

Would another way around this be to hook method_added and use that? The reason I say that is that typically when I have had this problem it hasn't really been at the point of migration. If I had a column and stuff breaks then I know where to go.

Much harder to diagnose is when a column you already have starts shadowing an important method, for example in one app I had a changed attribute that became problematic when I moved apps to 2.1 (clashes with dirty)

Actually that would be really tough because of methods that it's fine to override (before_save, to_xml etc...).