alphagov/marples — comment on commit 9fe166cafb757e4d13b3707b007ed24f1240af19
File:  line 0
By tomstuart:

They're both private, but a) Ruby enforces privacy by preventing you from calling a private method on any object (even `self`) using dot notation, except b) it special-cases setters because you have to use `self.foo=` to disambiguate it from an assignment to a local variable, so calling a private method with `self.` is permitted in that single case.