Functions and classes

def disp()

    puts "Hello World"

end

disp

Hello World

=> nil

def disp(name)

    puts "Hello #{name}"

end

disp("Rohit")

Hello Rohit

=> nil

disp "Rohit"

Hello Rohit

=> nil

disp

ArgumentError: wrong number of arguments (0 for 1)

class Greeter

    def initialize(name="world")

        @name=name

    end

    def say_hi

        puts "Hi #{@name}"

    end

    def say_bye

        puts "Bye #{@name}, Come back again."

    end

end

greeter = Greeter.new()

=> #<Greeter:0x7f8aadecbcf8 @name="world">

greeter = Greeter.new("Rohit")

=> #<Greeter:0x7f8aadec3a80 @name="Rohit">

greeter.say_hi

Hi Rohit

=> nil

greeter.say_bye

Bye Rohit, Come back again.

=> nil

Greeter.instance_methods

=> ["inspect", "tap", "clone", "say_bye", "public_methods", "__send__", "object_id", "instance_variable_defined?", "equal?", "freeze", "extend", "send", "methods", "hash", "dup", "to_enum", "instance_variables", "eql?", "instance_eval", "id", "disp", "singleton_methods", "taint", "enum_for", "frozen?", "instance_variable_get", "instance_of?", "display", "to_a", "method", "type", "instance_exec", "protected_methods", "==", "===", "instance_variable_set", "kind_of?", "respond_to?", "to_s", "say_hi", "class", "__id__", "tainted?", "=~", "private_methods", "untaint", "nil?", "is_a?"]

Greeter.instance_methods(false)

=> ["say_bye", "say_hi"]

class Greeter

    attr_accessor : name  #This adds setter(name=) and getter(name) function in Greeter class and all objects of it.

    def newfunc

        puts "Test"

    end

end