What you're terming "bag-of-things" languages can probably be more aptly described as languages which have both dict/tables/objects and first-class functions.

What you're terming "bag-of-things" languages can probably be more aptly described as languages which have both dict/tables/objects and first-class functions. While there isn't really a term (that I'm aware of) specifically for the this/self convention, both are idiomatic examples of dynamic scoping (compared to lexical scoping); that is, scope is determined at runtime by the most recent stack frame to define a given variable (ie, foo defines "this", then calls "bar", bar sees "this" as it was defined by foo), rather than at lex time.