ruby should I use self. or @

Question

Here is my ruby code

class Demo   attr_accessor :lines    def initialize(lines)     self.lines = lines   end end 

In the above code I could have used

    @lines = lines 

Mostly I see people using @ in initialize method. Is there a preferred way of doing among these two and why?

Answer 1

When you use @lines, you are accessing the instance variable itself. self.lines actually goes through the lines method of the class; likewise, self.lines = x goes through the lines= method. So use @ when you want to access the variable directly, and self. when you want to access via the method.

To directly answer your question, normally you want to set the instance variables directly in your initialize method, but it depends on your use-case.

Answer 2

self.lines is a method, @lines is the instance variable. In your constructor you'll want to use self.lines I would argue, but that's up for debate. It's just a stylistic difference, really. If you want a deeper discussion of direct vs. indirect variable access, read the chapter from Kent Beck's Smalltalk Best Practice Patterns.