> make sure no variable names are substrings of other variable names Did you miss the point about gorename's type safe renaming? It understands that pkgfoo.Ba

> make sure no variable names are substrings of other variable names Did you miss the point about gorename's type safe renaming? It understands that pkgfoo.Bar.Baz() is different than pkgbat.Bar.Baz(). So you can safely tell it to rename one, and it won't touch the other. And yes, it'll rename everywhere that was referencing the old name and fix that, too. Now I'll grant you that older refactoring tools were mostly text matching, but the fact that the std lib ships with a go parser and AST library means that anyone can write their own code parsing and refactoring tools.. and people are. > what you're showing here is called "polymorphism" I don't really want to argue about what counts as refactoring... what counts as "external behavior" depends a lot on how you look at a problem. To your customers, the CLI may be your external behavior, for partners, it may be your API, for the developer in the next cube, it may be the exported variables on your package/class/whatever. I'm not sure what you would count as qualities that make code easy to refactor. I like Go's implicit interfaces, nice tooling, and static typing to help make sure I'm not shooting myself in the foot. I honestly would like to hear what language you think is easy to refactor and why.