Arnaud J. wrote:
line_items << li ... So far, I know that has_many adds several methods, such as line_items<< and line_items=. I also know that, inside a method, an assignment to some "var" without "self." before it might confuse ruby which can take "var" for a local variable. So using self.var is "safer".
But here, there's no "self.line_items << li". Why does calling "line_items <<" is enough for this piece of code to understand that line_items isn't a mere variable ?
"self" is not needed here because the line is not an assignment (no "="). Unlike an assignment, for the line to have any meaning line_items must have been defined previously, so the interpreter sees no ambiguity.
