Ruby_Variables.md

Variables in ruby

There are 4 types of fundamental variables in ruby

1. Global variables:

Global variables begin with $. Uninitialized instance variables have the value nil and produce warnings.

$global_variable = 10
puts "Global variable is $global_variable"

2. Instance Variables:

An instance variable has a name that begins with @ and its scope is limited to the object to which reference self.

Two different objects, even when they belong to the same class, can have different values in their instance variables.

class Test
	def set_example (n)
		@example = n
	   	end
	
    def set_example2 (n)
		@example2 = n
	   	end
    end

3. Ruby Class Variables:

Class variables begin with @@ and must be initialized before they can be used in method definitions.

Referencing an uninitialized class variable produces an error. Class variables are shared among descendants of the class or module in which the class variables are defined.

Overriding class variables produce warnings.

class Workers
	@@number_of_workers = 0
    
	def initialize (name, id)
		@cust_name = name
		@cust_id = id
	    end

	def display_details()
	    puts "Worker id #@cust_id"
	    puts "Worker name #@cust_name"
	    end

	def total_workers()
	    @@number_of_workers += 1
	    puts "Total is: #@@number_of_workers"
	    end
	end

4. Ruby constants:

Constants begin with an uppercase letter. Constants defined within a class or module can be accessed from within that class or module, and those defined outside a class or module can be accessed globally.

class Example
	VAR1 = 100
	VAR2 = 200

	def show
		puts "Value of first Constant is #{VAR1}"
		puts "Value of second Constant is #{VAR2}"
	    end
	 end