#Ruby Class 1: Ruby’s instance variable and initialize method simplified

We read so many documents about ruby but do you think about some facts that we really don’t know. See below.

1. Instance variables are accessible across the class for that instance

Example:

class Test2
 def one
  @one = 1
  @two
 end
 def two
  @two = 2
  @one
 end
end

Here

t = Test.new
=> 
t.one is what ?
t.two is what ?

Can you guess?

t.one is nil why? t.one will return @two, but it is not initialized yet. We have to call t.two for intitializing it (the variable gets a value).

t.two is what?
Ans: 1
Why? because we already initialized @one by calling t.one above. If not it will also return nil.

So what is the purpose of instance variable if we are not getting its value when initializing the Class (say t = Test.new)

Here is the importance of ‘initialize’ method. Lets change the method named ‘two’ to ‘initialize’

class Test3
 def one
  @one = 1
  @two
 end
 def initialize
  @two = 2
  @one
 end
end

then you try:

t = Test.new
=>    ### See here already declared the variable @two

t.one
=> 2

Nice. So we can access that instance variable anywhere in the class.

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Author: Abhilash

Hi, this is Abhilash - Senior Programmer Analyst at CoMakeIT, specialised on web programming. Mainly working on Ruby On Rails platform since 2010.

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